Futures Position Size Calculator

Position size is the one input in a trade that is entirely under your control. You cannot decide whether the market respects your level; you decide, exactly and in advance, what being wrong costs. This calculator turns a stop-loss into a number of contracts, using the real tick values of the CME futures contracts most retail traders touch.

The logic is deliberately simple, because it should be: decide the money you are willing to lose on this trade, work out what one contract loses if the stop is hit, and divide. Then round down. The remainder is not wasted allowance — it is the margin that keeps a bad fill from turning a planned loss into an unplanned one.

How the number is calculated

Four steps, and the tool shows all of them so you can check the arithmetic rather than trust it:

1. Risk budget. Account size multiplied by your risk percent. On a $25,000 account at 1%, that is $250 — the entire cost of being wrong on this trade, before any contracts exist.

2. Stop distance in ticks. The absolute difference between entry and stop, divided by the tick size of the contract. A 10-point stop on the S&P with a 0.25 tick is 40 ticks.

3. Risk per contract. Ticks multiplied by the tick value. Forty ticks on MES at $1.25 a tick is $50; on the full-size ES at $12.50 a tick it is $500 — the identical trade idea, ten times the consequence.

4. Contracts. Risk budget divided by risk per contract, rounded down to a whole number. $250 ÷ $50 = 5 MES. $250 ÷ $500 = 0 ES, which is the calculator telling you something true.

When it returns zero

A zero is not a bug and not a reason to widen the risk percent until the trade appears. It means this stop, on this contract, on this account, cannot be traded inside your own rules. There are exactly three honest responses: trade the micro version of the same market, find a structurally valid tighter stop, or pass on the trade. The fourth response — raising risk from 1% to 2.5% because the trade looks too good to miss — is how accounts that were fine for six months disappear in three weeks.

Why the tick fields stay editable

The presets follow the published CME contract specifications, but exchanges change specs, brokers quote differently, and the instrument you trade may not be in the list at all. Every preset fills the tick size and tick value into editable fields so you can verify them against your broker's contract information before you rely on the result. For anything not listed, pick Custom and enter the two numbers yourself — the maths is identical for any instrument in the world.