Position Size Calculator
Position size calculator
Position size
Position value
Amount at risk
Reward : risk
This sizes a position so that being stopped out costs the percentage of your account you chose. It assumes your stop actually fills at your stop price, which in a fast crypto market is not guaranteed — gaps and thin books can make a real loss larger than the number shown. Not advice.
What this calculator does
It turns a risk decision into a position size. You tell it how large your account is, what percentage of it you are willing to lose on a single trade, where you would enter and where your stop would sit. It returns how many units that allows, what the position is worth, the dollar amount genuinely at risk, and — if you supply a target — the reward-to-risk ratio.
How to use it
- Account size — total capital you are trading with, not your net worth.
- Risk per trade — the percentage you accept losing if the stop is hit. Many experienced traders keep this at or below 1%.
- Entry and Stop — the distance between them is what defines your risk per unit.
- Target — optional. Supplying it gives you the reward-to-risk ratio.
Why this is the calculation that matters
Most accounts are not destroyed by bad analysis; they are destroyed by position size. A trader who is right slightly more often than not will still be wiped out by risking a third of the account on each idea, and a trader who is wrong more often than right can survive a long time risking a fraction of a percent. Sizing from a stop distance rather than from conviction removes the emotional part of the decision, which is precisely the part that fails under pressure.
The reward-to-risk figure is a useful filter. If a setup offers less than about 1.5 to 1, you need to be right a great deal of the time simply to break even after fees.
The assumption you must understand
This calculation assumes your stop fills at your stop price. In crypto that is not guaranteed. Markets gap, order books thin out at exactly the wrong moment, and during a violent move a stop can fill well below where you placed it — so a real loss can exceed the “amount at risk” shown here. Leveraged positions add liquidation risk on top, which this tool does not model at all. Size accordingly, and treat the output as a floor on your risk rather than a ceiling.
Frequently asked questions
What risk percentage should I use? That is your decision and depends on circumstances we cannot see. We will not name a number for you; we will say that larger percentages shorten how long you can survive a losing streak.
Does it account for leverage? No. It sizes the position; margin requirements and liquidation prices are exchange-specific and not modelled.
Is this advice? No. See our disclaimer.