Average Down Calculator.
Know the exact share count.
Enter your position and the average you want to end up at. You get the exact number of shares to buy, what they cost, and what your broker's commission takes out of the result.
Average Down Calculator
Find the exact shares needed to hit your target average
Your Position
A flat fee per order. It gets absorbed into your average, so you need slightly more shares to hit the same target.
Ready to calculate
Fill in your position details and hit Calculate
How the formula works
The arithmetic behind the answer, and why it sometimes refuses
Averaging down is a weighted average problem wearing a disguise. Your cost basis is one number divided by another: every dollar you have spent, over every share you have received. Buying more shares at a lower price adds a smaller number to the top than it does to the bottom, so the quotient falls. The only question worth calculating is how far it falls, and the answer runs in the opposite direction from the one people expect: you do not choose a share count and discover your new average, you choose the average you want and solve for the share count.
Formula
Additional Shares = (Owned × (Original − Target)) ÷ (Target − Current)Read the two halves separately and the behaviour of the tool stops being surprising. The numerator is the size of the problem: how many shares you hold, multiplied by how far each one has to move. Double the position and you double the work. The denominator is your leverage: the gap between today's price and the average you are aiming for. The wider that gap, the more each new share pulls, and the fewer you need.
This also explains the one case where the calculator refuses to answer. As your target creeps toward the current market price, the denominator shrinks toward zero and the required share count runs away to infinity. Set a target at the current price and the maths is asking you to buy an unbounded number of shares; set it below, and you are asking a $30 purchase to produce a $25 average, which no quantity of $30 shares can ever do. A target has to sit strictly between the current price and your existing average. When it does not, an error is the correct output, and a calculator that returns a tidy number instead is lying to you.
The practical consequence: the deeper the drawdown, the cheaper averaging down becomes in share terms. A stock 15% below your basis needs a large purchase to move your average meaningfully. The same stock 60% below moves it with a fraction of that. This is the honest reason averaging down feels compelling at the bottom - and the reason it is most dangerous there, because the same conditions that make the arithmetic cheap are the ones that make the business risky.
Three worked examples
The same formula, three positions, three very different answers
1. The textbook halving
You own 100 shares bought at $50, so $5,000 is committed. The stock now trades at $30 and you want a $40 average.
- Additional shares = (100 × (50 − 40)) ÷ (40 − 30) = 1,000 ÷ 10 = 100 shares
- Cost of the new shares: 100 × $30 = $3,000
- New position: 200 shares, $8,000 invested
- New average: $8,000 ÷ 200 = $40 exactly
Note what has and has not improved. Your average fell 20%, but your money at risk went from $5,000 to $8,000, and this single stock is now a 60% larger claim on your portfolio than it was this morning. The paper loss is unchanged at $2,000 - averaging down does not recover a loss, it changes the price at which the loss disappears.
2. The ambitious target
Same position - 100 shares at $50, trading at $30 - but now you want a $34 average, close to the market price.
- Additional shares = (100 × (50 − 34)) ÷ (34 − 30) = 1,600 ÷ 4 = 400 shares
- Cost of the new shares: 400 × $30 = $12,000
- New position: 500 shares, $17,000 invested
- New average: $17,000 ÷ 500 = $34
A target 15% lower than the first example demanded four times the shares and $12,000 instead of $3,000. This is the non-linearity that makes averaging down so easy to underestimate: the cost of each additional dollar of improvement rises steeply as you approach the market price. Most people who are shocked by a calculator's answer set a target too close to spot.
3. A small position with a flat fee
You own 40 shares at $12 ($480). The stock is at $7, you want an $9 average, and your broker charges a flat $9.95 per order.
- Without the fee: (40 × (12 − 9)) ÷ (9 − 7) = 120 ÷ 2 = 60 shares, costing $420
- With the $9.95 fee absorbed into basis: (40 × 3 + 9.95) ÷ 2 = 64.98 shares
- Cost of the new shares: 64.98 × $7 = $454.83, plus $9.95 commission = $464.78
- New average: ($480 + $464.78) ÷ 104.98 = $9.00
The fee is under $10 and it still moved the answer by five shares - roughly 8% more stock than the fee-free formula suggested. On a position this size the commission is 2% of the money being deployed, which is a meaningful drag on a plan whose entire purpose is to improve your basis by a few dollars a share. This is why the fee field exists, and why the result panel shows what the commission costs you per share rather than burying it in the total.
What commission does to the maths
Flat fees and percentage fees break the formula in different places
Almost every averaging-down calculator on the web quietly assumes your trades are free. For a US investor at a zero-commission broker that assumption is harmless. For everyone else - most non-US brokers, most contract-note markets, and anyone whose platform charges a percentage of trade value - it produces an answer that is confidently wrong. The two fee models fail in genuinely different ways, so this calculator handles them separately.
Flat fee
n = (Owned × (Orig − Target) + Fee) ÷ (Target − Current)The fee lands in the numerator. It is paid once no matter how large the order is, so it behaves like extra cost that has to be absorbed by buying more shares. The effect is small on a big order and material on a small one.
Percentage fee
n = (Owned × (Orig − Target)) ÷ (Target − Current × (1+p))The fee lands in the denominator. It raises the true cost of every share, so each one is less effective at pulling your average down. It does not just cost more - it reduces the leverage of the whole trade.
The case nobody warns you about: a percentage fee has a hard ceiling. If your commission rate makes the real cost of a new share meet or exceed your target average, no quantity of shares will get you there - each purchase now pushes your average up. Buying at $30 with a 40% total charge means every share genuinely costs $42, so a $40 target is unreachable no matter how much you spend. Enter that combination and the calculator returns an explanation rather than a number.
What cost basis actually means
Your cost basis - also called average cost, book cost, or adjusted cost base depending on where you file - is the average price you paid per share across every purchase, including the costs of buying. It does two jobs. Day to day it is the reference point that tells you whether you are up or down. At sale it is the number subtracted from your proceeds to produce the gain you are taxed on.
Cost Basis Formula
Cost Basis = Total Amount Invested ÷ Total Shares OwnedBuy 50 shares at $100 ($5,000), then 50 more at $60 ($3,000): $8,000 across 100 shares gives a $80 basis. Add a $10 commission to each order and it is $8,020 across 100 shares, or $80.20. That twenty cents looks trivial and is exactly the kind of detail that compounds across a dozen tranches into a number that no longer matches your broker's statement.
One warning that catches people out at tax time: the blended average is the right number for judging your position, but it is not necessarily the number your tax authority uses when you sell part of it. That distinction is covered in the tax section below. If you are tracking several purchase lots and want them itemised rather than blended, the cost basis calculator handles lot-by-lot entry.
The recovery you need afterwards
Why a 50% loss needs a 100% gain, and what averaging down does to that number
Losses and gains are not symmetrical, and the asymmetry gets worse the further you fall. A stock that drops 50% has to double just to return to where it started, because the 50% gain is now calculated on the smaller base. The general form is simple: recovering a loss of L requires a gain of L ÷ (1 − L).
| Loss from your basis | Gain needed to break even |
|---|---|
| 10% | 11.1% |
| 25% | 33.3% |
| 40% | 66.7% |
| 50% | 100% |
| 70% | 233% |
| 90% | 900% |
Averaging down attacks this table directly. In the first worked example above, a $50 basis against a $30 price is a 40% loss needing a 66.7% rally. Moving the basis to $40 turns it into a 25% loss needing a 33.3% rally - the required move is halved, and it is now a move the stock has to make from $30 to $40 rather than all the way back to $50.
That is the genuine case for the strategy, and it comes with a genuine cost that the table hides. You halved the recovery you need, but you did it by putting 60% more money behind the outcome. If the stock keeps falling, the larger position loses faster in absolute terms than the smaller one would have. Averaging down trades a lower required recovery for a higher exposure to being wrong. Whether that is a good trade depends entirely on whether you are right about the business - which is why every section below is about that question rather than this one. The break-even calculator works the same numbers including transaction costs.
When averaging down works
Averaging down is a bet that the market's new price is wrong and your original thesis is right. That bet pays when the gap between price and value is genuinely temporary, and the conditions below are the ones under which it usually is. Note that none of them are about the chart.
The business is intact
Revenue, margins and competitive position are unchanged; what moved was sentiment, an index reweighting, or a quarter that missed on timing rather than substance.
The whole sector fell
The entire peer group is down by a similar amount. A sector-wide de-rating on rates or macro fear says far less about this company than a fall it took alone.
You have the horizon
Averaging down needs years, not weeks. If the money is spoken for before the thesis can play out, you will be forced to sell at whatever price the market offers.
The position still fits
Even after the addition, this holding stays inside the concentration limit you set for a single name. If it does not, the arithmetic is irrelevant.
You would buy it fresh
The honest test: with no existing position and no loss to recover, would you open this trade today at this price? If not, you are managing a feeling rather than a portfolio.
The fall has a nameable cause
You can state in one sentence why the price fell and why that reason is temporary. Not being able to is the single most reliable signal to stay out.
These conditions are demanding on purpose. Averaging down is the only common portfolio action that increases your exposure to a decision that has so far been wrong, so the bar for it should be higher than the bar for a new position, not lower. If you find yourself arguing with more than one of the six, that is the answer.
When it destroys capital
The failure mode has a shape. A position falls, you add, it falls further, you add again because the average is now so close to recoverable, and the holding you were least confident about becomes the largest thing you own. Nothing in that sequence involves a decision to concentrate - it is what happens when each step is judged on its own.
The fundamentals changed with the price
Guidance was cut, a key customer left, a drug failed, the moat was breached. The market repriced because the business is worth less. Your thesis did not survive; adding money to it does not revive it.
You cannot say why it fell
If the explanation is that the chart looks oversold, you are averaging into a story you have not read. Cheapness is not a thesis.
The dilution risk is live
A company burning cash with a weak balance sheet may need to issue equity at the bottom. You can be right about the recovery and still lose, because your claim on it gets cut.
The position is already oversized
If this name is past your concentration limit, averaging down is not a valuation decision - it is a decision to abandon your risk framework at the worst possible moment.
You are adding to feel better
The relief of watching your average tick down is real and has nothing to do with returns. If the appeal is the number turning green sooner, that is loss aversion wearing a spreadsheet.
It is leveraged or borrowed money
Averaging down on margin converts a survivable drawdown into a forced sale. The strategy needs the ability to wait, and margin is precisely the removal of that ability.
There is no calculator for these. The arithmetic on this page will happily tell you the share count for a company heading to zero, and it will be correct in exactly the way that does not matter. Run through the list before you run the numbers. When not to average down goes through each of these in detail.
Planning a tranche ladder
Decide the whole plan before the first purchase
The single most effective protection against the failure mode above is to make the entire plan in advance, while you are still calm and the position is still small. A tranche ladder is that plan written down: how many additions you will make, at what price levels, in what sizes, and the total beyond which you will not go regardless of what the price does.
A three-tranche example on a $10,000 conviction budget
- Tranche 1 — $4,000 at the initial entry. This is the position if nothing else happens.
- Tranche 2 — $3,000 if the price falls 20%, and only if the thesis is re-checked and still holds.
- Tranche 3 — $3,000 if the price falls 35%, same condition.
- Hard cap — $10,000 total. A fourth tranche does not exist, no matter how cheap it gets.
Two details make this work. The first is the front-loaded sizing: putting the largest tranche in first means a stock that simply goes up does not leave you with a token holding, which is the quiet cost of laddering that most descriptions omit. The second is the hard cap, and it is the only part that actually protects you. Price triggers without a cap are just a schedule for running out of money slowly.
Re-checking the thesis at each level is not a formality. The condition that invalidates the plan is not the price falling - you planned for that - it is the reason for the fall turning out to be a real change in the business. If tranche 2 arrives alongside a guidance cut, the correct action is to abandon the ladder, not to execute it because it was written down. The averaging down strategy planner models a full ladder with the cap enforced, and the position size calculator sets the budget in the first place.
Tax treatment and the wash sale rule
US rules, and the two places averaging down interacts with them
Which basis method applies
The blended average this page calculates is the right lens for judging your position, but it is not automatically the number the IRS uses when you sell part of it. For individual stocks the default is first-in first-out: sell 50 of your 200 shares and the 50 oldest - the expensive ones you bought first - are treated as sold, which produces a larger loss than the blended average suggests. You can instead identify specific lots at the time of sale if your broker supports it. The average cost method, the one that matches the number on this page, is only permitted for mutual fund shares and certain dividend reinvestment plans, not for ordinary stock.
The wash sale rule
Averaging down by itself does not trigger a wash sale. The rule is about selling, not buying: it applies when you realise a loss and acquire substantially identical securities within 30 days before or after that sale. When it applies, the loss is disallowed for the current year and added to the basis of the replacement shares, so it is deferred rather than lost outright.
The trap worth knowing: the 30-day window runs in both directions. If you average down today and then sell some of your older, higher-cost shares at a loss within the next 30 days - a perfectly reasonable way to tidy a position - that purchase you already made can disallow the loss on the sale. The buy came first, which is exactly why people miss it.
Holding periods are the other interaction. Each tranche starts its own clock, so an averaged-down position typically contains both short-term and long-term lots at once, taxed at different rates. This is a summary of US federal rules and not tax advice; the definitions live in IRS Publication 550 and Topic no. 409. Rules differ substantially elsewhere - the UK, Canada and India each use different matching rules - so check the ones you file under. Tax implications of averaging down covers this at length.
Other names for this calculator
Same tool, same maths, many names
This one page is the canonical home for every variation on the phrase. A stock average down calculator, an averaging down calculator, a share average down calculator, a stock cost average calculator, an average down stock calculator, a stock averaging down calculator, an averaging stocks calculator, a double down calculator, or kalkulator average down are all asking for the same arithmetic: how many shares at today's price to reach a target average. There is one tool here rather than eleven near-identical pages, because splitting the same content across a dozen URLs helps nobody - not readers, and not search engines trying to work out which one to show.
A few genuinely different questions do get their own tools, because the inputs differ rather than just the wording: cost basis across multiple lots, planning a tranche ladder, the break-even exit price, and how many shares a budget buys.
Frequently asked questions
What is an average down calculator used for?▾
It tells you exactly how many extra shares to buy at today's price to pull your average cost down to a number you choose. Instead of buying a round lot and finding out afterwards where your average landed, you set the average you want and the calculator returns the share count and the cash it takes to get there.
How do I calculate my average share price?▾
Average share price = total amount invested divided by total shares owned. Buy 100 shares at $50 ($5,000) and 100 more at $30 ($3,000) and you hold $8,000 across 200 shares, so your average is $40. The arithmetic is identical for any number of purchase lots: add up every dollar spent, add up every share received, divide one by the other.
What is the formula for averaging down to a target price?▾
Additional shares = (shares owned x (original average - target average)) divided by (target average - current price). Owning 100 shares at $50 with the stock at $30 and a $40 target gives (100 x 10) / 10 = 100 shares. The formula only returns a positive answer when the target sits strictly between the current price and your existing average, because no purchase can drag your average below the price you are paying for the new shares.
Does brokerage commission change how many shares I need?▾
Yes, and this calculator accounts for it. A flat fee is absorbed into your basis, so you need slightly more shares to reach the same average: a $9.99 commission on the example above moves the answer from 100 shares to 101. A percentage fee is more corrosive, because it raises the real cost of every share you buy. Above a certain rate your target becomes mathematically unreachable, and the calculator says so instead of returning a number that cannot happen.
How much does the stock have to recover after I average down?▾
Less than before, which is the entire point. Recovering a loss of L percent requires a gain of L / (1 - L). Down 40% from $50 to $30, you need a 66.7% rally to see $50 again. Average down to a $40 basis and you only need the stock to reach $40, a 33.3% move from $30. The required recovery has roughly halved, but you are carrying twice the position into it.
Is averaging down a good strategy?▾
It is a good strategy for a temporarily mispriced business and a poor one for a deteriorating business, and the price chart cannot tell you which you own. The useful test is not whether you want the loss back, because you always do. It is whether you would open this position today, at this price, with fresh money and no history. If the answer is no, adding is a way of avoiding a decision rather than making one.
What is the difference between averaging down and dollar-cost averaging?▾
Averaging down is reactive and discretionary: the price fell, and you chose to buy more of that specific holding. Dollar-cost averaging is scheduled and indifferent: a fixed amount goes in on a fixed date whether the market is up, down or flat. DCA lowers your average as a side effect of the schedule. Averaging down lowers it as the goal of a judgement you are making about one company.
How many times should I average down on the same stock?▾
Decide the answer before the first purchase, not during the third. A workable approach is a fixed ladder: three tranches at pre-set price drops, with the total position capped at a share of the portfolio you set in advance. The damaging version is the unplanned one, where every new low produces another purchase and the position quietly grows into your largest holding precisely because it has performed worst.
Can I average down on ETFs and index funds the same way?▾
The arithmetic is identical; the risk is not. A broad index fund cannot go to zero the way a single company can, so adding to a falling index is a bet on the market recovering rather than on one management team being right. That is a materially safer bet historically, which is why scheduled buying into index funds is ordinary practice while adding to a single falling stock demands a specific reason you can state out loud.
Does averaging down trigger the wash sale rule?▾
Buying more shares on its own does not. The wash sale rule is triggered by selling at a loss, not by buying. It applies when you sell shares at a loss and acquire substantially identical shares within 30 days before or after that sale, in which case the loss is disallowed for now and added to the basis of the replacement shares. If you are averaging down without selling anything, the rule is not in play. IRS Publication 550 carries the full definition.
Which cost basis method applies to my averaged-down position?▾
In the US, individual stocks default to FIFO unless you identify specific lots at the time of sale, and the average cost method is only available for mutual fund shares and certain dividend reinvestment plans - not for ordinary stock. So the blended average here is the right number for judging the position, while the basis your broker reports on a partial sale may follow a different lot entirely. Rules differ by country; check the ones that apply to you.
What should I do instead if I do not want to add to a loser?▾
Three alternatives, all legitimate. Hold and do nothing, which is a decision even though it does not feel like one. Sell and redeploy the capital into a better idea, harvesting the tax loss where your jurisdiction allows it. Or cut the position part-way, which reduces the risk without requiring you to be right about the timing. Averaging down is one option among these, not the default.
Sources and further reading
- Publication 550: Investment Income and Expenses — Internal Revenue Service
Definition of the wash sale rule, substantially identical securities, and the basis adjustment applied to replacement shares.
- Topic no. 409, Capital gains and losses — Internal Revenue Service
The one-year holding period that separates short-term from long-term treatment, and the annual capital loss deduction limit.
- Dollar Cost Averaging — U.S. Securities and Exchange Commission (Investor.gov)
The regulator's plain definition of scheduled investing, which is the discipline averaging down is most often confused with.
Related averaging down guides
Disclaimer: This calculator is for educational purposes only and is not financial or tax advice. It performs arithmetic on the numbers you enter; it cannot see your tax position, your time horizon, or the rest of your portfolio. Consult a qualified financial adviser before making investment decisions.
Guides that explain this calculator
- What Is Averaging Down? Complete Beginner's Guide (2026)The mechanics, the maths, and the narrow conditions where it works.
- Averaging Down on ETFs vs Individual Stocks: Same Maths, Different Bet
- When NOT to Average Down: 7 Red Flags to WatchSeven red flags, with a real bankruptcy as the worked example.
- How to Calculate Average Share Price (Formula + Worked Examples)The weighted-average formula, worked through multiple lots.