Crypto position size calculator

How crypto position sizing works

A trade has three numbers that must agree: the money you are prepared to lose, the price at which you accept you were wrong, and the size of the position. Fix the first two deliberately and the third is decided for you. That is position sizing, and it matters more in crypto than almost anywhere else, because coins regularly move several percent in a day and a position sized on a hunch can lose a large part of an account on one bad candle.

The method is the same as the forex lot size calculator, without lots or pips. Crypto is sized directly in coins and its stop distance is a price difference. You turn your risk percentage into money, work out what one coin loses if the stop is hit (the price difference plus the fees on both trades) and divide.

The calculator reads the direction from the stop: a stop below the entry is a long, a stop above it is a short. It then shows the position in coins and in your account currency, the margin it needs at the leverage you chose, and a warning if the trade does not fit.

It works the same for spot and for perpetual futures. On spot, leave leverage at 1: you can only short through a derivative, and the position value has to fit inside your balance. On a perpetual, enter the leverage you plan to use and read the liquidation row before you trade.

The formula

Money at risk = Balance × Risk %
Loss per coin = |Entry − Stop| + Fee × (Entry + Stop)
Coins = Money at risk ÷ Loss per coin
Position value = Coins × Entry and Margin = Position value ÷ Leverage

The fee term charges the taker rate on the entry and again on the stop, because a stop-loss normally fills as a market order. If you enter with a limit order at a lower maker rate, the real fee is a little smaller and this result errs on the safe side.

Two checks follow. If the position value is larger than balance × leverage, you do not have the margin for it, and the calculator tells you the minimum leverage it needs. And when leverage is above 1x, it estimates the isolated-margin liquidation price with the same approximation as the liquidation calculator, at a 0.5% maintenance rate, and warns you if the stop sits beyond it.

A worked example

A hypothetical setup: a 10,000 USDT account, 1% risk per trade, a Bitcoin long from 60,000 with a stop at 58,800, and a 0.05% taker fee.

1. Money at risk: 10,000 × 1% = 100 USDT.
2. Stop distance: 60,000 − 58,800 = 1,200, which is 2% of the entry.
3. Fees per coin: 0.0005 × (60,000 + 58,800) = 59.40.
4. Loss per coin: 1,200 + 59.40 = 1,259.40.
5. Position size: 100 ÷ 1,259.40 = 0.0794 BTC, worth 4,764.17 USDT.

If the stop is hit, the price move costs 95.28 and the two fees 4.72, together the 100 USDT you planned. Ignore the fees and you would have bought 0.0833 BTC and lost about 105. At 1x the margin is the full 4,764.17, under half the account. Now tighten the stop to 59,700 (0.5%) with the same risk: the position grows to 0.2779 BTC, worth 16,673.61 USDT, more than the balance, so the calculator flags that it needs at least 1.7x leverage. Fees are now 16.63 of the 100 at risk.

Same risk, different stops

The table shows how the position changes when only the stop moves. Every row risks the same 100 USDT (1% of a hypothetical 10,000 USDT account) on a Bitcoin long from 60,000, with a 0.05% taker fee, at 1x:

Two patterns stand out. The position shrinks as the stop widens, so the money lost when it is hit stays the same, which is the whole point of sizing this way: you can put the stop where the chart says it belongs. And fees take a much bigger share of a tight stop, a sixth of the loss at 0.5% against about 1% of it at 10%. Only the 0.5% stop needs more than the balance, which is when the calculator shows the leverage warning.

Common mistakes

Using leverage to set the size. "I have 1,000 and use 20x, so I trade 20,000" puts the size first and the risk nowhere. Size from the stop, then use only as much leverage as the margin requires. More leverage on the same position adds nothing but a closer liquidation price.

A stop beyond liquidation. At 20x a long is liquidated after a fall of roughly 4.5%. A 6% stop on that trade will never fire: the exchange closes it first and you lose the margin rather than your planned risk. The warning row catches this.

Forgetting slippage. A stop is a trigger, not a fill price. In a sharp move, or in a thin coin, it fills worse, sometimes a lot worse. The lesson on slippage and spreads shows how to allow for it; on small coins a slightly lower risk percentage is a sensible buffer.

Risking too much per trade. Crypto losing streaks come quickly. At 1% per trade, ten losses in a row cost about 9.6% of the account; at 5% they cost about 40%. The risk management for crypto positions lesson covers per-trade and daily limits, and the risk management guide applies the same thinking to forex and gold.

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