Position Sizing for Prop Challenges: A Practical Guide

Position sizing means choosing how big each trade is, so that a stop-out costs a small, planned share of your account. On a challenge, size against the loss limits first: pick a risk per trade, check how many losses in a row your plan can absorb, and only then turn that risk into a trade size. All amounts below are in the account's currency, on a simulated (demo) account.

Start from the limits, not from the trade

The limits set the room you have. Two-Step: 5% max daily loss and 10% max loss. One-Step: 3% and 6%. Both are equity-based.

The table shows how many full losses in a row it takes to reach or pass the daily limit at different risk levels.

Risk per trade	Two-Step (5% daily)	One-Step (3% daily)
0.25%	20 losses	12 losses
0.5%	10 losses	6 losses
1%	5 losses	3 losses
2%	3 losses	2 losses

These are simple sums. Trading costs and fast markets can make a real loss larger than planned. And because the limits are equity-based, open trades count, so you can reach a limit sooner than the table suggests. The guide to daily loss vs max loss explains why.

A useful test: if two or three bad trades in a row would put you near a limit, your risk per trade is too high for that plan.

The three-step formula

1. Risk amount = account size × risk percentage.
2. Work out what one lot would lose if your stop were hit. This comes from your own plan: the distance to your stop and the value of that distance for one lot.
3. Lot size = risk amount ÷ loss per lot at your stop.

Example A: a 100K account

You risk 0.5%. That is 500. Suppose one lot would lose 2,000 if your stop were hit. Then 500 ÷ 2,000 = 0.25 lots.

If the stop were twice as far away, one lot would lose 4,000. The size would halve to 0.125 lots, and the money at risk would still be 500. A wider stop means a smaller size, not a bigger risk.

Example B: a 25K account

You risk 0.5% again. That is 125. With the same 2,000 loss per lot, 125 ÷ 2,000 = 0.0625 lots. Round down to the smallest step your platform allows, for example 0.06 lots. Always round down, never up. Rounding up quietly raises your risk above the number you chose.

Example C: a 50K account on the One-Step

You risk 0.5%. That is 250. The One-Step daily limit is 3%, which is 1,500 on this account. Six full losses in a row at 250 each would reach it. If your personal daily stop is half of the limit, 750, you stop after three full losses. The sizing is the same formula each time. Only the limits change.

Count all the risk that is open at once

Your daily cushion is shared by every open trade.

• Three open trades at 0.5% each put 1.5% at risk together. On a 100K account that is 1,500.
• Trades on related markets can move together. Count them as one larger position, not as separate small ones.
• Set a cap on total open risk, and write it next to your risk per trade. For example, if your personal daily stop is half the plan's limit, keep total open risk well inside it.

Equity-based limits include floating losses, so total open risk is the number that can hit your equity at the same moment.

Leverage is a ceiling, not a target

Leverage in the challenge is 1:100 on the Two-Step and 1:50 on the One-Step. In the funded stage it is 1:40 on both. Leverage limits how large a position your margin can hold. It does not tell you how much to risk.

If you size by risk, the same logic carries into the funded stage even though leverage is lower there. Lower leverage means each position needs more margin, so check your margin before opening a large position.

Keep your sizing consistent

The terms ask for market-standard risk management. They list among forbidden practices:

• position sizes that are materially disproportionate to your usual trading behaviour;
• a materially higher or lower number of positions than usual, where it looks like an attempt to exploit the program or bypass its risk parameters;
• materially different strategies, risk profiles or execution between the challenge and the funded stage.

You can still adjust your size over time. A gradual change, made for a reason you can write down, is different from a sudden jump. The simplest safeguard is a fixed range. Choose a risk percentage, stay in it, and change it only on purpose, never mid-session to catch up.

Do not forget costs

Commissions are a cost of trading on these accounts. Include them when you work out what a trade really risks, especially if you place many small trades. A plan that looks fine before costs can be much tighter after them.

A quick pre-trade checklist

1. Is my risk percentage the one I wrote down?
2. Have I counted every open trade, not just this one?
3. Would a loss here, plus my open trades, keep me inside my personal daily stop?
4. Did I round the size down?
5. Do I know the daily reset time and the news windows today?

For wider habits around size and stopping rules, read how to pass a prop challenge. The full list of limits is in the rules.

Key points

• Choose risk per trade first. Convert it into a size second.
• At 1% risk, five full losses reach the Two-Step daily limit and three reach the One-Step one.
• Lot size = risk amount ÷ loss per lot at your stop. Round down.
• Count total open risk. Trades on related markets can lose together.
• Leverage is a ceiling on size, not a guide to how much to risk.
• Keep your sizing consistent, and include costs in the real risk of a trade.