Position size & risk calculator
Size a trade for MetaTrader 5, then check it survives a losing streak — not just a single stop.
Free · No install · Runs in your browser
Diagnosis
What this setup implies, before you run it.
Lot size for different stop distances
- Lot size that keeps your risk the same
- Your current input
Survival
What the same risk setting looks like after a streak of losses. Balance-proportional sizing shrinks the stake as you lose; a fixed lot does not.
| Losing streak | Balance-proportional | Fixed {lots} lots | Balance left |
|---|---|---|---|
| — | — | — | |
| — | — | — | |
| — | — | — | |
| — | — | — | |
| — | — | — |
Risk of ruin
How to use it
- Enter your numbersType your own values into the fields, or choose your MetaTrader report if the tool reads a file. The values already there are only a starting example.
- Read the result and the diagnosisThe large number answers the question. The cards under it say what looks wrong and what to change.
- Try a fix or take it furtherApply a suggested change to see the result move, follow the link to the next tool, or copy the link to come back to the same inputs.
How this is calculated
Lot size is risk amount divided by (stop distance × pip value), then rounded down to your broker's lot step. Rounding up would breach the risk you set, so the exact figure is shown next to the tradable one instead of replacing it.
Pip value is pip size × contract size, converted into your account currency with the rate you supply. For instruments where contract size is broker-specific — indices, metals, crypto, commodities — no value is shown at all, because guessing one would quietly change every number on this page.
Risk of ruin uses Balsara's analytic solution: the probability of losing a fixed share of the account before the edge plays out, given a win rate and a reward-to-risk ratio. It assumes independent trades of constant risk, which is optimistic — real losing streaks cluster. Treat it as a floor, not a forecast.
Questions and answers
Is it free, and do I need an account?
Free · No install · Runs in your browser. No account needed to calculate.
Is anything uploaded?
Everything above runs in your browser. No balance, symbol or setting is sent to a server, and there is nothing to delete afterwards.
How far can I trust the result?
Figures are calculations from your inputs, not predictions. Nothing here is investment advice.
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Terms behind this tool
- Average True RangeA volatility indicator measuring the average size of recent price movement, in price units. EAs use it to set stop distances and position sizes that adapt to current conditions instead of assuming yesterday's.
- Lot sizeThe unit of trade volume in MT5. One standard lot is 100,000 units of the base currency; a micro lot is 1,000 units, entered as 0.01.
- Position sizingThe rule that turns a trading signal into a lot size — most usefully by fixing the loss a single trade may cost and letting the stop distance decide the volume.
- Risk/reward ratioThe ratio of potential profit to potential loss on a single trade, calculated as take-profit distance divided by stop-loss distance. It fixes the win rate a strategy needs in order to break even.
- Stop-lossA stop-loss is a price level attached to a position at which the broker closes it automatically, capping the loss on that trade. It lives on the broker's server, so it works even when the terminal does not.
Let an EA size every trade for you
This calculator turns your risk and stop distance into a lot size. In AIStrategyMiner Builder you wire your entry and exit rules together as blocks and set the risk per trade, with no code.
- Set the risk and the stop distance you used here, then compile a standard .ex5 file for MetaTrader 5.
Check the finished EA in MetaTrader 5 before you trust it. The numbers on this page come from what you typed; they are not a forecast of results.
