Position Size Calculator
Work out the lot size for any trade from your account balance, the risk you are prepared to take and your stop distance. Free, no signup, and nothing you type leaves your browser.
Enter four figures. The calculator returns the amount you are risking in account currency, and the position size that risk produces at your stop distance.
Position Size Is a Consequence, Not a Setting
Most traders pick a lot size and discover their risk afterwards. The calculation runs the other way round. Risk per trade is the decision. Stop distance is set by the strategy. Lot size is simply what falls out of the two.
That ordering matters more with an Expert Advisor than it does manually, because an EA will apply whatever sizing rule it is given, thousands of times, without ever asking whether the result still makes sense. An EA that lets you set lots directly, with no risk-based sizing option, is handing you the least useful of the three controls — and it will keep using that fixed lot size as your balance halves.
Two Things That Will Make This Calculation Wrong
Pip value is not a fixed number
It varies by currency pair and by the currency your account is denominated in. The figure is stable for pairs quoted in your account currency and moves for everything else, so a single remembered number will be wrong more often than it is right. Take it from your broker's contract specifications for the specific instrument, on the day.
Nothing here models correlation
Risking 1% on six positions is not the same as risking 6% across six unrelated ones, if those six are effectively the same bet on the dollar. This calculator sizes one position in isolation. A basket or grid EA holding several correlated trades at once carries a combined exposure this figure does not show, and that combined exposure is what actually threatens the account.
Frequently Asked Questions
What risk per trade should I set on an EA?
Where do I find the pip value for my pair?
Does this work for MT4 and MT5?
Why is my broker rejecting the lot size this gives me?
Is it free, and do you store what I enter?
Before You Let an EA Size Your Trades
Getting the lot size right is worth very little if the EA doing the trading was never worth running. We publish two free documents that cover the checks we run before we will cover a product at all: the EA Red Flag Checklist, and a Broker and VPS Quick Reference covering the conditions an EA actually needs to perform as advertised.
Both are yours the moment you submit — the download page opens immediately, with no waiting and nothing to find in your inbox. The marketing email tick-box is optional and you can leave it blank.
The Sizing Is the Easy Part
A correct lot size protects you from one bad trade. It does nothing about an Expert Advisor whose track record was never evidence in the first place — and on the products we have examined, that is the more common failure by a wide margin.
We test every EA against the same eight criteria, publish the ones that fail, and currently recommend exactly one. The reviews carry the arithmetic, the account each figure came from, and the date it was read.
This tool performs arithmetic on figures you supply and runs entirely in your browser. It is not financial advice and it is not a recommendation to trade. Position size is one input among several — it does not account for correlated exposure, margin requirements, your broker's minimum lot and step sizes, or slippage against your stop. Trading forex and CFDs carries a high level of risk and may not be suitable for all investors.
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