How position size is calculated
Position sizing answers one question: how many contracts can I trade so that if my stop is hit, I lose no more than I decided to risk? The formula has three steps:
- Risk budget = account size × risk percent.
- Risk per contract = stop distance in ticks × tick value.
- Contracts = risk budget ÷ risk per contract, rounded down to a whole number.
Worked example. A $25,000 account risking 1% has a $250 budget. Trading MES with a 10-point stop is 40 ticks (10 ÷ 0.25), and each tick is worth $1.25, so one contract risks $50. $250 ÷ $50 = 5 contracts. (Illustration only — not a recommendation.)
Position size examples by account size
Here is how the same 1% risk rule plays out across account sizes. Each column uses a typical day-trading stop for that contract, and the numbers are the whole contracts that keep a stopped-out trade inside 1% of the account.
| Account | 1% risk | ES 10-pt stop · $500/contract | NQ 20-pt stop · $400/contract | MES 10-pt stop · $50/contract | MNQ 20-pt stop · $40/contract |
|---|---|---|---|---|---|
| $10,000 | $100 | 0 | 0 | 2 | 2 |
| $25,000 | $250 | 0 | 0 | 5 | 6 |
| $50,000 | $500 | 1 | 1 | 10 | 12 |
| $100,000 | $1,000 | 2 | 2 | 20 | 25 |
| $150,000 | $1,500 | 3 | 3 | 30 | 37 |
Assumes 1% risk per trade. Illustration only — not a recommendation. Your stop and risk percent will differ; use the calculator above for your own numbers.
What the table shows:
- Small accounts need micros. At $10,000, a 10-point ES stop risks $500 per contract against a $100 budget — so the answer is 0 contracts. The same stop on MES risks $50 per contract, which allows 2.
- Size scales with the account. Going from $10,000 to $100,000 takes MES from 2 to 20 contracts and ES from 0 to 2 at the same stop.
- A zero is useful information. It means the stop is too wide for that account and risk percent — tighten the stop, step down to the micro, or accept a larger risk percent knowingly.
How risk percent changes the size
The risk percent is the other lever. Here is a $50,000 account trading MNQ with a 20-point stop ($40 per contract) at different risk levels:
| Risk per trade | Risk budget | MNQ contracts |
|---|---|---|
| 0.5% | $250 | 6 |
| 1% | $500 | 12 |
| 2% | $1,000 | 25 |
Doubling the risk percent roughly doubles the contracts — and the dollars lost when the stop is hit.
Futures contract specifications
Tick size and tick value are what turn a stop distance into dollars. These are the standard CME values the calculator uses:
| Contract | Tick size | Tick value | Point value |
|---|---|---|---|
| ES | 0.25 | $12.50 | $50 |
| MES | 0.25 | $1.25 | $5 |
| NQ | 0.25 | $5.00 | $20 |
| MNQ | 0.25 | $0.50 | $2 |
| YM | 1.00 | $5.00 | $5 |
| MYM | 1.00 | $0.50 | $0.50 |
| RTY | 0.10 | $5.00 | $50 |
| M2K | 0.10 | $0.50 | $5 |
| CL | 0.01 | $10.00 | $1,000 |
| MCL | 0.01 | $1.00 | $100 |
| GC | 0.10 | $10.00 | $100 |
| MGC | 0.10 | $1.00 | $10 |
Using the result well
- Size from the stop, not the other way around. Place the stop where the trade idea is wrong, then size the position to that distance. Don't shrink the stop just to fit more contracts.
- Use micros when the stop is wide. If the result is 0 or 1 contract on a mini, the micro gives finer steps.
- Mind your limits. Brokers and prop firms set contract caps and daily loss limits — use the max-contracts field to respect them.
- Remember what it ignores. Slippage, commissions and gaps can make a real loss larger than the planned one.
Frequently asked questions
How do you calculate position size in futures?
Take your account size times the percent you're willing to risk to get a dollar risk budget. Divide that by the risk per contract (stop distance in ticks times the tick value). Round down to a whole number of contracts. For example, $25,000 at 1% risk is $250; a 40-tick stop on MES risks $50 per contract (40 x $1.25), so the size is 5 contracts.
How many contracts should I trade?
There is no single right number - it depends on your account size, the risk you accept per trade, and how wide your stop is. Many traders risk a small fixed percentage of the account per trade so no single loss does serious damage. This calculator shows the maximum whole contracts that stay inside the risk you enter.
What is the tick value for ES and NQ?
On the E-mini S&P 500 (ES) one tick is 0.25 points and is worth $12.50. On the E-mini Nasdaq-100 (NQ) one tick is 0.25 points and is worth $5.00. The micro versions, MES and MNQ, are one-tenth of those: $1.25 and $0.50 per tick.
Should I trade micro or mini contracts?
Micros let you size positions in finer steps, which helps when your stop is wide or your account is small. If the calculator returns 0 contracts on a mini, the stop risks more than your budget - switching to the micro contract often gives a usable size.
Can I use this for prop firm evaluations?
Yes, as a starting point. Enter your max-contracts limit to cap the result. Prop firms also have drawdown rules (trailing or static) and contract limits that vary by firm and account, so always check your firm's current rules. See our guide on prop firm rules for NinjaTrader automation.
How many MES contracts can I trade with a $10,000 account?
It depends on your stop and risk percent. At 1% risk ($100) with a 10-point stop on MES ($50 per contract), the size is 2 contracts. A tighter stop allows more contracts; a wider one allows fewer.
How does position sizing prevent account blowups?
Proper position sizing ensures no single trade can devastate your account. By risking only 1–2% per trade, you can survive long losing streaks that are statistically inevitable in trading.
What is a good risk percentage per trade?
Most professional traders risk between 0.5% and 2% of their account per trade. Risking 1% means even 10 consecutive losses would only result in a 10% drawdown, which is recoverable. Try different values in the risk per trade field to see how the contract count changes.
What is a good risk/reward ratio?
A risk-reward ratio of 1:2 or higher is generally considered good, meaning you stand to gain $2 for every dollar you risk. However, the ideal ratio depends on your win rate. Enter your ratio in the reward : risk field to see the profit target in ticks and dollars.
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