ATR size
ATR size
Position size adjusted for volatility, via ATR.
Stop distance
24.0 pips
Risked amount
100.00 $
Size (lots)
0.41
Units
41,000
Same risk · 100 $ · two markets
This calculator sizes a position from the ATR (Average True Range), an indicator that measures the average range of recent candles. Instead of picking an arbitrary stop distance, you start from the volatility actually observed on the instrument: the ATR multiplied by a coefficient gives a stop distance, and that distance determines how many lots your risk percentage allows.
In practice, the tool converts the ATR distance into pips, works out the amount your risk percentage represents, then derives the size in lots and units. The size is truncated down to the nearest 0.01 lot, so the displayed amount at risk is never exceeded. A choppy market produces a wider stop and therefore a smaller position · a quiet market does the opposite. Everything runs in your browser, nothing is sent or stored.
The formula, in plain words
Stop distance = ATR × multiplier, converted into pips by dividing it by the instrument's pip size. Amount at risk = account balance × risk percentage. Size in lots = amount at risk ÷ (stop distance in pips × pip value per lot, in your account currency). The result is truncated to 0.01 lot steps, then multiplied by the contract size to give the units.
A worked example, number by number
Take the calculator's default values: a 10,000 $ account, 1% risk, EURUSD, an ATR of 0.0012 and a multiplier of 2. First the distance: 0.0012 × 2 = 0.0024, which is 24 pips (one EURUSD pip is 0.0001). Then the risked amount: 1% of 10,000 $ = 100 $. Finally the size: on EURUSD one pip is worth 10 $ per lot, so 100 ÷ (24 × 10) = 0.4166 lots. The calculator shows 0.41: it always truncates down to the nearest hundredth instead of rounding, because at 0.42 lots those 24 pips would cost 100.80 $ · more than what you decided. Result: 0.41 lots, or 41,000 units, for an actual risk of 98.40 $.
Reference table · same account, rising volatility
10,000 $ account, 1% risk, EURUSD, multiplier 2: when the ATR doubles, the stop doubles and the size follows inversely. Figures truncated as in the calculator.
| ATR (pips) | Stop (pips) | Size (lots) | Units |
|---|---|---|---|
| 5 | 10 | 1.00 | 100,000 |
| 10 | 20 | 0.50 | 50,000 |
| 15 | 30 | 0.33 | 33,000 |
| 20 | 40 | 0.25 | 25,000 |
| 30 | 60 | 0.16 | 16,000 |
What the number does not tell you
The ATR describes past volatility, never the volatility of your next trade: a news release can move the price far beyond the recent average range, and an ATR-based stop can be jumped like any other · the real loss then exceeds the calculated amount. The calculation also takes its pip value from a reference table: on pairs not quoted in dollars, your broker may show a slightly different figure. Finally, a stop at 2 ATR is a statistically reasonable distance, not a level from your analysis: it can land in the middle of nowhere, where nothing in the market structure justifies an exit.
The classic mistake
Reading the ATR on one timeframe and trading on another. The daily ATR on EURUSD runs in tens of pips, the 5-minute ATR in a few pips: the same multiplier produces stops that have nothing in common. Whoever reads the daily ATR for a trade held a few hours gets an oversized stop and a tiny position · whoever does the opposite puts the stop inside the noise, at a distance the market crosses several times a day. The ATR to enter is the one from the timeframe where you will actually manage the trade.
Frequently asked questions
Where do I find the ATR value to enter?
On any chart that offers the ATR indicator (default period 14). Read the value shown on the timeframe you are planning the trade on and copy it as is, in price terms: 0.0012 on EURUSD, 1.5 on an index, and so on. The timeframe matters: an H1 ATR and a daily ATR give very different distances.
What is the multiplier for?
A stop placed at exactly 1 ATR is often hit by ordinary market noise. The multiplier widens the distance: at 2, the stop sits at twice the recent average range. The larger the multiplier, the further away the stop and the smaller the calculated position, since the amount at risk stays the same.
How is this different from a regular position size calculator?
A regular calculator starts from a stop distance you set yourself in pips. Here the distance comes from measured volatility: when the market gets choppy, the stop widens and the size shrinks automatically, and the other way round when it calms down. The sizing math itself is identical in both tools.
Why does the size change from one day to the next when I always risk the same percentage?
Because the ATR moves with the market. Your percentage fixes the amount at risk in money, and the ATR fixes the distance that amount is spread over: the larger the distance, the less each pip may cost, so fewer lots. With 100 $ at risk, a 20-pip stop allows 0.50 lots and a 40-pip stop allows 0.25 · the amount at risk itself never moves.
Does this work on indices or gold, or only on currency pairs?
The logic is the same everywhere: the ATR is read in the instrument's price units, and the calculator converts it into pips using that instrument's own pip size. On gold or an index, enter the ATR exactly as your chart shows it (1.5 points, for example) and check that the symbol you typed matches your chart's · it determines the pip size and pip value used.
See also
Position size
Work out how many lots to open from your account size, risk percentage and stop loss distance in pips. Free, no sign-up, runs entirely in your browser.
Profit
Work out the profit or loss of a forex, index or metals trade from the entry price, the exit price and the lot size. Free in-browser calculator, no sign-up.
Pip value
Work out what one pip is worth for any currency pair, based on your lot size and account currency. Free, instant, and everything runs in your browser.