Position size calculator
Enter your account balance, how much you want to risk and where your stop goes, and I will tell you how big the position has to be so that, if the stop is hit, you lose only that. It is the calculation from the guide on how much to risk per trade.
Position size1,000 USDT
You lose if the stop is hit20 USDT
In coins, at the entry price0.01667
Margin you need1,000 USDT
If the price falls to 58,800, 2% from your entry, the stop closes the position and you lose 20 USDT: 1% of your account.
Work out your liquidation price
Without fees or slippage: if the stop is hit, you lose a little more. Before you open, check the size on your exchange.
How much to open by distance to the stop
With a 2,000 USDT account, this is what you can open to lose 1% or 2% if the stop is hit. The closer you place the stop, the bigger the position:
| Distance to the stop | Risking 1% | Risking 2% |
|---|---|---|
| 0.5% | 4,000 USDT | 8,000 USDT |
| 1% | 2,000 USDT | 4,000 USDT |
| 2% | 1,000 USDT | 2,000 USDT |
| 3% | 666.67 USDT | 1,333.33 USDT |
| 5% | 400 USDT | 800 USDT |
| 10% | 200 USDT | 400 USDT |
With a very tight stop, the position comes out bigger than the account and you need leverage to open it. What you lose at the stop doesn’t change, but liquidation gets closer: check it before you open.
The formula I use
It is the same calculation as in the guide, in three steps:
- Risk in USDT = balance × risk per trade. With 2,000 USDT and 1%: 20 USDT.
- Distance to the stop = (entry − stop) ÷ entry, without the sign. Entry at 60,000 and stop at 58,800: 1,200 ÷ 60,000 = 2%.
- Position size = risk ÷ distance. 20 ÷ 0.02 = 1,000 USDT, about 0.0167 BTC.
The margin is the size ÷ the leverage: at x5, 200 USDT; at x10, 100 USDT. If the stop is hit you lose 20 USDT in both cases; leverage only decides how much money is held.
To warn you about liquidation I use the formula from the liquidation price calculator, on isolated margin and with a 0.5% maintenance margin. With the stop 2% away and x50, liquidation would come before the stop.
Why a small percentage
What you risk on each trade decides how much you have left after a losing streak, and losing streaks happen to everyone, even with a good method. After ten losses in a row:
| Risk per trade | Account after 10 losses in a row |
|---|---|
| 1% | 90.4% |
| 2% | 81.7% |
| 5% | 59.9% |
| 10% | 34.9% |
At 1% you still have almost the whole account; at 10%, you are left with a third and need to nearly triple it to get back to where you started. How to choose the percentage is in how much to risk per trade, and where to place the stop, in stop loss and take profit.
What the calculation leaves out
- The fees for opening and closing: with 1,000 USDT and 0.06% each time, 1.20 USDT more. How they are charged is in maker and taker fees.
- Slippage: a market stop is filled at whatever price is available, and in a sharp move it can be filled somewhat worse.
- The positions you already have open: if they go in the same direction and in coins that move together, the risk adds up.
If you don’t want to go above 1%, expect the real loss to come out slightly higher than the calculator’s figure.
Frequently asked questions
How do you calculate position size?
Divide what you are willing to lose, in USDT, by the distance to the stop as a decimal. With 20 USDT of risk and the stop 2% away, the position is 1,000 USDT. That is the calculation this calculator does.
What is the 1% rule?
Not losing more than 1% of the account on a single trade if the stop loss is hit. The position size is worked out from that limit, not the other way round.
Does leverage change what I lose?
No, if the position size is the same: leverage only decides how much margin is held. What changes is the distance to liquidation, which gets closer the more leverage you use.
What if the position comes out bigger than my account?
It means the stop is very close to the entry. To open it you need leverage, and then you have to check that liquidation sits beyond the stop. The calculator warns you if it doesn’t.
Does it work for a short?
Yes. Put the stop above the entry and the calculation is the same: the distance to the stop, without the sign.
Does it include fees?
No. If the stop is hit, you also lose the opening and closing fees, and a market stop can be filled somewhat worse. With large positions and tight stops, it shows.