Prop Firm Guide
How to size a futures trade for a prop firm
Most traders don't fail a prop firm evaluation because their entries are bad. They fail because their size is wrong. Trade the same contract count on every setup and your dollar risk swings all over the place, until one wide-stop loss eats the trailing drawdown and the account is gone.
Here is how to size every futures trade off your stop and your firm's rules, so the risk stays flat and the eval stays alive.
Why a fixed contract count blows accounts
Say you always trade 3 contracts of ES. A setup with a 4 point stop risks 600 dollars. A setup with a 12 point stop risks 1,800 dollars. Same "3 contracts," triple the risk.
Your account doesn't care how many contracts you traded. It cares how many dollars you lost. Fixed-size trading means your real risk is whatever the stop happens to be that day, which is exactly the number a trailing drawdown punishes. The fix is to flip it around: decide the dollars first, then let the stop set the contracts.
The position size formula
- Dollar Risk is the fixed amount you lose if the stop hits. A common rule is a small percent of the account, often 0.5 to 1 percent. On a 50,000 dollar account, 1 percent is 500 dollars.
- Stop in points is the distance from your entry to your stop, in points, not ticks.
- Point Value is what one full point is worth on that contract. ES is 50 dollars a point, NQ is 20, and the micros are a tenth of the full size.
Point values you need
| Contract | Symbol | $ / point |
|---|---|---|
| S&P 500 E-mini | ES | $50 |
| Micro S&P 500 | MES | $5 |
| Nasdaq 100 | NQ | $20 |
| Micro Nasdaq | MNQ | $2 |
| Dow E-mini | YM | $5 |
| Russell 2000 | RTY | $50 |
| Crude Oil | CL | $1,000 |
| Micro Crude | MCL | $100 |
| Gold | GC | $100 |
| Micro Gold | MGC | $10 |
A worked example
50,000 dollar account, risking 1 percent, which is 500 dollars. You go long ES with a 5 point stop.
Your real risk is 2 × 5 × $50 = 500 dollars. Exactly your budget. Now tighten the stop to 2.5 points and the same 500 dollar budget buys 4 contracts. The dollars stayed flat, the size adjusted to the stop. That is the entire point of sizing this way.
Where prop firm rules change the math
Sizing off your stop keeps risk flat, but a prop evaluation stacks hard limits on top of it. Your size has to respect all of them at once.
- Trailing drawdown. The most you can fall from your account's peak before it fails. It tightens as you make money. Size so a normal losing streak never reaches it.
- Daily loss limit. Some firms cap how much you can lose in a single day. Your per-trade risk times the most trades you would take in a day has to stay under it.
- Max contracts. Every firm caps contracts per account size. If your stop-based math says 8 contracts but the firm allows 5, you trade 5. The cap wins.
- Consistency rule. Caps how much of your total profit can come from one day, often 50 percent. It doesn't change your size, but it means you pass on several steady green days, not one home run.
Apex, Topstep, MyFundedFutures, TakeProfitTrader and Lucid each set these numbers differently, and they change them regularly. Always confirm the live figures with your firm before you trade.
Skip the math
The PreBell calculator does all of this for you. Pick your prop firm and account, enter your entry, stop and risk, and it returns your exact contract count, your dollar risk, your R:R, and flags the moment a trade would break a firm rule. No spreadsheet, no signup.
Open the free calculator →Free · No account required
Common questions
What is the position size formula for futures?
Contracts equal your dollar risk divided by your stop in points times the point value. For ES at 50 dollars a point, a 500 dollar risk and a 5 point stop gives 2 contracts.
How many contracts should I trade on a prop firm evaluation?
There is no single right number. Your size comes from your stop distance, your dollar risk, and your firm's max-contract cap. Size off the stop so your dollar risk stays constant, then cap it at the firm's limit.
Why do I keep failing prop firm evaluations?
Most blown evals come down to sizing and the trailing drawdown, not bad entries. A fixed contract count makes your real dollar risk move with the stop, and one wide-stop loss eats the drawdown buffer.
PreBell is an educational tool. Nothing here is financial advice or a promise of any result, and trading futures carries substantial risk of loss. Point values and prop firm rules can change, confirm the current numbers with your broker and firm before you trade.