Position sizing for prop firm challenges: how much to risk, and why
On a prop firm challenge, the quickest way to fail isn't missing the profit target. It's breaking a loss limit, often on a day that started well. Position sizing for a challenge is different from sizing your own account, because the rules punish one bad day far more than your own account ever would.
The two limits that matter
Almost every challenge has two loss rules:
- A daily loss limit: how much your account can fall within one trading day.
- A maximum loss: how far your account can ever fall overall.
As an example, at the time of writing (October 2026) FTMO's 2-Step Challenge uses a 5% daily loss and a 10% maximum loss, both measured against the initial balance, with the maximum loss fixed. Its 1-Step Challenge is tighter: a 3% daily loss, and a 10% maximum loss that trails up behind your highest end-of-day balance. Other firms use different figures and calculations, and they change their rules, so read your own firm's rules before you size a single trade.
How many losses can you survive?
On a $100,000 account with a 5% daily and 10% maximum loss, risking a fixed amount per trade:
| Risk per trade | Per trade | Full losses before the daily limit | Full losses before the maximum loss |
|---|---|---|---|
| 0.25% | $250 | 20 | 40 |
| 0.5% | $500 | 10 | 20 |
| 1% | $1,000 | 5 | 10 |
| 2% | $2,000 | 2 (the 3rd breaches it) | 5 |
At 2%, two losing trades and a bit of slippage on a third ends the challenge in a morning. That's why most experienced challenge traders sit between 0.25% and 1%.
The trade-off: speed against survival
Lower risk means slower progress. Suppose your target is 10% and your trading averages +0.2R per trade (for example, a 40% win rate at 1:2):
| Risk per trade | R needed for 10% | Trades needed on average |
|---|---|---|
| 0.5% | 20R | about 100 |
| 1% | 10R | about 50 |
The averages hide streaks, so real results will be bumpier. But the lesson is clear: there's no risk level that's both fast and safe. Pick the one your edge and your nerves can live with, and check the firm's time limits (many no longer have one).
Worked examples on a $100,000 account
Risking 0.5% = $500 per trade. Challenge accounts are usually in dollars, so no currency conversion is needed.
EURUSD · stop 20 pips · 1.00 lot loses $200 → 2.50 lots
NAS100 · stop 60 points · if 1.00 lot = $1 per point, it loses $60 → 8.33 lots
The NAS100 line shows why you must check the contract size on your firm's server: if one lot were $10 a point there, the right size would be 0.83 lots. See NAS100 and US30 lot size.
Five habits for passing on risk
- Set a personal daily stop at half the firm's limit. With a 5% limit, stop at 2.5% down. You'll never be one bad fill from failing.
- Count open risk, not just closed losses. Three trades at 1% open together is 3% at risk on the daily limit.
- Leave a buffer for slippage. Stops can fill worse than planned around news. Many traders stay flat for the big releases.
- Know when the trading day resets. Firms reset the daily limit at a fixed time (often midnight on the firm's server or in Central European time). Know the exact time for yours.
- Don't size up near the target. The last 2% is where people get impatient. Keep the same risk all the way.
Track your challenge like a pro
The Trader's Ledger shows your balance, return and maximum drawdown from your starting balance, plus your results in R by setup and session, so you can see how close you are to the limits. £19 once, with a free 49-page trading course.
Get The Trader's LedgerFor the general rules on choosing a risk level, read how much to risk per trade. To turn it into a lot size quickly, use the free lot size calculator (choose USD as the account currency for most challenges).
Frequently asked questions
How much should I risk per trade on a prop firm challenge?
Most experienced challenge traders risk 0.25% to 1% per trade. Lower risk is slower, but it lets you survive the losing streaks every strategy has without breaching the daily or maximum loss.
Do floating losses count towards the daily loss limit?
At most firms, yes: the limit is checked on equity, which includes open trades, commission and swap. Check your firm's rules to be sure.
What is a trailing maximum loss?
A maximum loss that moves up as your account makes new highs (at some firms only at the end of each day), and never moves back down. It's stricter than a fixed one, because profits you give back still count against you.
How do I calculate lot size on a $100k challenge?
Decide your risk (for example 0.5% = $500), find your stop, then divide: $500 divided by what 1.00 lot loses at that stop. On gold with a $5 stop, 1.00 lot loses $500, so the answer is 1.00 lot.
Educational content only, not financial advice. Trading carries a high level of risk and you can lose more than you expect. Examples use illustrative prices.