How to calculate position size
Work out the money first. Decide what share of the account one losing trade may cost, turn that into dollars, then see how many units your stop allows.
Futures: Contracts = floor( (Balance × Risk %) ÷ (Stop ticks × Tick value) )
Forex: Lots = floor( (Balance × Risk %) ÷ (Stop pips × Pip value per lot) )
Futures stops are measured in ticks, the smallest price step a contract allows. Forex stops are measured in pips, which is 0.0001 on most pairs and 0.01 on yen pairs. The tick value comes from the exchange contract spec; our futures calculator hub lists it for every contract. The forex answer is rounded down to 0.01 lots, the smallest size most brokers accept.
Futures contract size table
How many contracts a $25,000 account can trade when it risks 1% on a 20-tick stop. Tick size differs by contract, so the same tick count is a different distance on each one.
| Contract | Tick size | Tick value | Risk per contract | Contracts allowed |
|---|---|---|---|---|
| ES tick value | 0.25 | $12.50 | $250 | 1 |
| NQ tick value | 0.25 | $5 | $100 | 2 |
| MES tick value | 0.25 | $1.25 | $25 | 10 |
| MNQ tick value | 0.25 | $0.50 | $10 | 25 |
| CL tick value | 0.01 | $10 | $200 | 1 |
| GC tick value | 0.1 | $10 | $200 | 1 |
Position size calculator worked examples
Futures: MES against ES
A $25,000 account risking 1% has a budget of $250. A 20-point stop on MES is 80 ticks of 0.25, and each tick is worth $1.25, so one contract risks $100. That allows 2 MES contracts.
The same stop on full-size ES risks $1,000 per contract, which is more than the whole budget, so the calculator returns 0. ES is ten times the size of MES, and that alone decides whether the trade fits.
Forex: EUR/USD against USD/JPY
A $10,000 account risking 1% can lose $100. On EUR/USD a pip is worth $10 per standard lot, so a 25-pip stop costs $250 per lot. That allows 0.40 lots (40,000 units).
On USD/JPY at 150.00, the pip is worth 1,000 yen per lot, or $6.67. The same 25-pip stop allows 0.60 lots (60,000 units). When the dollar is the base currency, the pip value moves with the rate, so enter the current rate before you size the trade.
Two rules that keep the number honest
Round down. Rounding up turns a 1% rule into something larger on every trade where the maths doesn't divide evenly. And size off the stop your setup needs. Shortening a stop to fit a bigger size breaks the rule while it looks followed. Our guide to how much to risk per trade covers how to pick the percentage in the first place, and why 0.5–2% is where most rules land.
On a funded or evaluation account, the firm's drawdown limit usually binds before your own rule. Divide the drawdown you have left by the number of losses in a row you want to survive, and use that as your risk per trade. Whether the limit is checked at the close or intraday changes how much room one wide stop takes. More on that for prop firm traders.
Check the size you actually traded
The calculator gives the size you meant to take, and a journal records the size you took on every trade. The ExpectancyIQ trading journal records each trade's result in R-multiples, so a run where 1% quietly became 2.5% shows up on a chart. Once your sizing is steady, the expectancy calculator tells you whether those trades pay over time. This page is educational, not financial advice.