How to calculate crypto position size from your risk
By Daily Edge · Updated · Educational only, not financial advice.
Most traders choose a position size by feel: a round number of coins, or whatever "seems like enough". Sizing from risk turns this around. You decide first how much you're willing to lose if the trade is wrong, and the stop-loss distance then tells you how big the position can be. This guide covers the formula, works through spot and futures examples with simple numbers, and shows where fees and leverage fit in. The free position size calculator does the arithmetic for you.
What position size means
Position size is how much you buy or sell in one trade, in coins (0.05 BTC) or in dollars ($3,000 worth). It's not the same as your risk. A large position with a tight stop can risk less than a small position with a wide stop. What you actually lose if the stop is hit depends on two things together: the size, and how far price travels from entry to the stop.
Sizing from risk keeps that loss roughly the same from trade to trade, so a single bad trade has the same effect on your account whether the stop is close or far.
The formula
Risk amount = account size × risk per trade (%)
Stop distance = |entry price − stop-loss price|
Position size (coins) = risk amount ÷ stop distance
Position value (USD) = position size × entry price
Risk per trade is a choice you make, not a number this guide can give you. Write it down as part of your trading plan and keep it the same until you decide on purpose to change it. Your R-multiple is then measured against this risk amount: a loss at your stop is −1R.
Worked example: a spot trade
Example numbers only. They are round, hypothetical figures chosen to keep the maths easy, not a recommendation or any exchange's actual prices or fees.
- Account size: $10,000
- Risk per trade: 1%, so risk amount = $10,000 × 1% = $100
- Entry: $50,000; stop-loss: $48,000, so stop distance = $2,000
- Position size = $100 ÷ $2,000 = 0.05 coins
- Position value = 0.05 × $50,000 = $2,500
If price falls to the stop, the loss is 0.05 × $2,000 = $100, which is the amount chosen at the start (before fees, covered below). Notice that the position value, $2,500, is much larger than the $100 at risk. That's normal: the stop, not the position value, limits the loss.
Same risk, wider stop
Move the stop to $45,000 (a $5,000 distance) and keep the $100 risk: 100 ÷ 5,000 = 0.02 coins, worth $1,000. A wider stop means a smaller position. This is the main habit position sizing builds: you don't widen a stop and keep the same size.
Short trades
For a short, the stop sits above the entry. The formula is the same, using the absolute distance. Example: entry $50,000, stop $51,000, risk $100 → 100 ÷ 1,000 = 0.1 coins.
Include fees in the stop distance
Trading fees are charged on the position value on the way in and on the way out, so the real loss at the stop is a little more than the formula shows. One way to allow for this is to add the round-trip fee per coin to the stop distance.
Example numbers only. They are round, hypothetical figures chosen to keep the maths easy, not a recommendation or any exchange's actual prices or fees.
With a hypothetical 0.1% fee per side, on the spot example above:
- Fee per coin ≈ (entry + stop) × 0.1% = ($50,000 + $48,000) × 0.001 = $98
- Effective stop distance = $2,000 + $98 = $2,098
- Position size = $100 ÷ $2,098 ≈ 0.0477 coins
Slippage, where a stop order fills worse than its trigger price, can add to the loss in fast markets. Neither the formula nor the calculator can predict it. For how each trading cost works, see crypto trading fees explained. For published rates from each exchange's own fee page, see crypto exchange fees compared. The position size calculator has a fee-per-side field that does this adjustment for you.
Futures and leverage: margin, not risk
A common mix-up is to think leverage changes how much you risk. With risk-based sizing it doesn't. The formula already sets the position size from your stop. Leverage only decides how much of your own money the exchange holds as margin for that position.
Example numbers only. They are round, hypothetical figures chosen to keep the maths easy, not a recommendation or any exchange's actual prices or fees.
Take the same $2,500 position (0.05 coins at $50,000, stop at $48,000):
- At 1x the position needs about $2,500 of your money.
- At 5x the initial margin is about $2,500 ÷ 5 = $500.
- At 10x it's about $250.
In each case the loss at the $48,000 stop is still about $100. What changes is the liquidation price. The higher the leverage, the closer it moves to your entry. If the liquidation price sits between your entry and your stop, the position can be closed by the exchange before your stop is reached, usually with extra fees. So with futures, check that the liquidation price is well beyond your stop. The liquidation price guide explains how it's calculated, and the liquidation calculator works it out from your inputs. Exchanges' margin rules differ, so the exchange's own figure is the one that counts.
If you're new to leverage, practising with leverage on paper first lets you see how margin and liquidation behave without real money.
Lot size vs position size
Some platforms trade in lots or contracts, each worth a fixed amount of the coin. Work out the position size in coins with the formula first, then divide by the coin amount per contract shown in the exchange's contract specifications, and round down so you don't exceed your risk. Exchanges also have minimum order sizes and size increments. If the size the formula gives is below the minimum, the trade doesn't fit your risk at that stop.
Risk per trade and the odds of a drawdown
Position sizing controls the loss on one trade. Over many trades, how much you risk each time, together with your win rate and average win and loss, shapes how deep a losing streak can take your account. Losing streaks happen even with a positive edge, and a higher risk per trade makes each one deeper.
The risk of ruin and expectancy calculator shows this relationship: enter your own win rate, average R and risk per trade to see your expectancy and the odds of reaching a drawdown level you choose. It uses the numbers you give it, so its output is only as good as your own trade history. For the terms, see expectancy, risk of ruin and drawdown in the glossary.
Common mistakes
- Sizing first, stop second. Picking a size and then placing the stop wherever the loss "feels OK" means the stop no longer reflects where the trade idea is wrong.
- Moving the stop without resizing. A wider stop at the same size is a bigger risk.
- Treating leverage as risk. Leverage changes margin and the liquidation price, not the loss at your stop.
- Ignoring fees and minimums. Small accounts and tight stops are affected most.
- Not recording it. Logging planned risk next to the actual result is the only way to see whether you stick to your sizing. A trading journal makes this routine.
Frequently asked questions
What is position size in crypto trading?
Position size is how much of a coin you buy or sell in one trade, in coins or in dollars. Sizing from risk means picking the size so that, if your stop-loss is hit, you lose a set amount you chose in advance.
What is the position size formula?
Position size in coins = amount you are willing to lose ÷ distance from entry to stop. The amount you are willing to lose is your account size × your risk per trade. Multiply the coin amount by the entry price to get the position value in dollars.
How do you calculate position size in crypto futures?
Use the same formula: risk amount ÷ stop distance gives the position size. Leverage then decides how much margin that position needs, not how much you lose at the stop. Check that the liquidation price is further away than your stop.
How do you calculate lot size in crypto?
Many crypto exchanges size orders in coins or in quote currency rather than lots. Where an exchange uses contracts or lots, divide the position size from the formula by the coin amount per contract or lot, as shown in that exchange's contract specifications, and round down.