Calculator
Enter an entry price and a stop-loss price to see your position size.
Why size by risk, not by feel
Every trade has two numbers that matter before you place it: how much you could make, and how much you could lose. A lot of beginners only think about the first one — they pick a coin, guess at a quantity that "feels right," and only find out what the guess actually cost them after the stop is hit.
Sizing by risk flips the order. Before you enter, you decide the one number you actually control: how much of your account you're willing to lose if you're wrong. A common starting point is a small, fixed percentage — 1% is popular precisely because it's boring. One bad trade barely dents the account, and it takes a long losing streak to do real damage. From that percentage and your stop-loss distance, the position size falls out as arithmetic — no guessing, no rounding to a number that "looks right."
This also makes different trades comparable. A tight stop 2% away and a wide stop 8% away shouldn't use the same position size — the tight stop lets you hold more coins for the same dollar risk, the wide stop demands fewer. Sizing by feel tends to get this backwards: eyeballing "a normal amount" of a coin means risking a different sum every time, without ever deciding to.
None of this predicts whether a trade wins. It only fixes how much a loss costs you when it happens — which is the part of the outcome that was always yours to control.
FAQ
Do I need an account?
No. This calculator runs entirely in your browser.
How is position size calculated?
Position size in coins equals your dollar risk (account balance times risk percent) divided by the distance between your entry price and your stop-loss price. Multiply by the entry price to get the position size in dollar notional.
What's a reasonable risk percentage?
There's no single right answer — it depends on your account size, strategy and how many trades you run at once. 1% per trade is a common starting point because a single loss stays small relative to the account. This calculator defaults to 1% but you can change it to whatever you're testing.
Why does the direction (long or short) matter?
It doesn't change the math, but it changes what should happen next. If your stop-loss is below your entry price, you're sizing a long; if it's above, you're sizing a short. Getting this backwards means your stop and target are on the wrong sides of your entry.
Practice this on real history — set a stop, size the trade, and replay it candle by candle.
Open the free backtesterFreeBacktest is an educational tool. Nothing here is investment advice. Past results — real or simulated — do not predict future results.