Crypto position size calculator — size the trade from the risk
The largest linear-perp position your own risk limit allows, from your equity, the percentage you are willing to lose, and where your stop sits. Sized in the base asset — BTC, ETH, SOL — because on a linear contract one contract is one unit.
Largest compliant size
0.083 base units
Risk budget$100.00
Stop distance per unit$1200.00
Truncated down to the step, so the loss stays inside your budget. Before fees and slippage — each makes the real loss larger.
What this covers
—Linear USDT/USDC contracts, where loss scales with price distance times quantity.
—One position at a time. It does not know about anything else you have open.
—Excludes fees and slippage — each makes the real loss larger. The full check adds them.
—No liquidation modelling: that is a venue-specific fact this page does not calculate.
Formula and assumptions
—Risk budget = account equity × risk percentage.
—Risk per base unit = |entry − stop| (linear contract, multiplier 1).
—Position size = risk budget ÷ risk per unit, truncated down to your quantity step.
—USDT/USDC settlement treated as USD one-to-one.
—Assumes the stop fills at its price. Fast markets fill worse.
position_size.crypto.v1
Worked example
Example — not a recommendation.
Account$10,000
Risk per trade1% = $100
Entry → stop60,000 → 58,800 ($1,200 per BTC)
Raw size0.0833 BTC
Largest compliant size (step 0.001)0.083 BTC
Common mistakes
×Sizing from margin rather than from the stop. Margin is what leverage changes; the stop decides the loss.
×Reading a 2% stop distance as 2% account risk. They are different numbers unless size makes them equal.
×Rounding the size up to a cleaner number — the loss then exceeds the budget you just stated.
×Adding leverage to 'afford' a bigger size and keeping the same stop: the planned loss grew with the size.
Limitations
This is arithmetic on numbers you supplied. It does not know your broker, your account, or the market. It does not predict price, does not say whether to take a trade, and is not advice. Maximelion is not affiliated with any broker or prop firm, and nothing here is endorsed by one.
Last reviewed 31 July 2026