Position Sizing
Position sizing is how you decide the contract or share count on each trade. It\'s the lever that translates a strategy into actual dollar risk per trade — and the lever that determines how a copy trading setup scales across accounts of different sizes.
Three common methods
Fixed contracts: same number on every trade, regardless of account balance or volatility. Simplest, predictable, makes risk-per-trade a fixed dollar amount based on stop distance.
Multiplier of master: the follower trades a constant ratio of the master account's size. If the master trades 2 contracts and the multiplier is 0.5, the follower trades 1. Useful when the master and follower have different account sizes but the same strategy.
Percent of account balance: contract count adjusts based on the follower's current equity. As the account grows, sizing grows; as it draws down, sizing shrinks. Mathematically clean but can chase performance.
Why it matters more for copying
When you copy trades across multiple accounts, each follower has different rules. A $50K combine has a smaller daily loss limit than a $150K funded account. A trailing drawdown that's tighter on one account constrains what you can size at, full stop.
A copier that only supports a single sizing rule across all followers forces a compromise — you size for the most constrained account, leaving capital underused on the larger accounts. Per-follower sizing is what makes simultaneous combines and funded accounts work without either over-risking small accounts or under-using large ones.
Common mistakes
Sizing all accounts identically and assuming "the strategy will work the same way." It won't. A 2-contract strategy on a $50K combine is a different risk profile than the same 2 contracts on a $150K funded account.
Using percent-of-balance during a drawdown sequence. The sizing scales down with equity, which means recovering from a drawdown takes longer because you're trading smaller. Some traders prefer this; others find it psychologically punishing.
How to think about it for prop firm work
For combines: size to the daily loss limit. Pick a stop distance you're comfortable with, calculate the max contracts that keep one trade within ~30% of the daily limit. That gives you room for 2-3 losers before the day is forced to end.
For funded accounts: size to the trailing drawdown distance, not the daily limit. The trailing rule is the long-term constraint; daily is just the worst-day cap. A strategy that's safe against the trailing drawdown will rarely bump the daily limit.
Frequently asked questions
How do I turn a position size into a dollar risk per trade?
Multiply your contract count by the stop distance in ticks by the per-tick dollar value of the instrument. For example, 2 contracts with a 10-tick stop on an instrument worth $12.50 a tick risks 2 × 10 × $12.50 = $250. That dollar figure — not the contract count — is what you should be sizing against your daily loss limit and drawdown.
Should smaller accounts use micros instead of minis?
Often, yes. Micro contracts (MES, MNQ) carry roughly a tenth of the tick value of their mini counterparts, so they let a small combine take the same setup at a fraction of the dollar risk. That granularity is what makes it possible to keep risk-per-trade sensible on a tight account instead of being forced into an oversized single mini.
Should position size change with volatility?
Many traders scale it down when the expected stop distance widens, so dollar risk per trade stays roughly constant across calm and volatile sessions. Fixed-contract sizing ignores this — the same contract count is a bigger dollar risk when your stop has to be wider — which is a common reason a strategy that felt safe suddenly bumps the daily limit.
Which sizing method is best when copying across different account sizes?
There's no single winner, but multiplier-of-master and percent-of-balance are the two that adapt to each follower's size, while fixed contracts is simplest when accounts are similar. The real requirement is that the method be set per follower — a single global rule forces you to size for the most constrained account and waste capital on the rest.
Can each copied account have its own sizing rule?
It should. PropCopy supports per-follower sizing (fixed, multiplier, or percent of balance), so a $50K combine and a $150K funded account can each run the size that fits their own rules from the same master — without over-risking the small account or under-using the large one.
Want to put this into practice?
Ready to copy trades across your prop firm accounts?
Join the waitlist for priority onboarding and launch-week perks.