# Position size calculator

Enter your account size, how much of it you are willing to lose on this trade, your entry and your stop. The calculator gives the position that loses that amount at the stop, with fees on both fills counted as part of the loss.

## How the size is worked out

The stop decides the size. Leverage doesn't. Leverage only changes how much margin the position ties up.

On a **linear** contract (BTC-USDT), your account and your profit are in USDT, and the size is in coins:

```text
risk = account x risk %
size in coins = risk / (|entry - stop| + fee x (entry + stop))
margin = size x entry / leverage
```

On an **inverse** contract (BTC-USD), your account and your profit are in the coin, and the size is in dollars of face value. The loss per dollar is 1/exit minus 1/entry, so the formula changes:

```text
risk = account in coins x risk %
size in dollars = risk / (|1/entry - 1/stop| + fee x (1/entry + 1/stop))
margin in coins = size in dollars / (entry x leverage)
```

## An example

A $10,000 account risking 1% is willing to lose $100. Long at $100 with a stop at $98, ignoring fees, is a $2 move, so the size is 50 coins, or $5,000 of notional. At 5x that takes $1,000 of margin. At 10x it takes $500. The loss at the stop is $100 either way.

## What to watch for

- **A stop past liquidation never fills.** At 10x, a long is liquidated about 9.5% below entry. A stop 12% below entry would not be reached first, and the calculator says so.
- **Margin above your account** means this leverage can't hold the position. Raise the leverage or take a smaller trade.
- **Stops can slip.** A stop-market order fills at the next price available, so a fast move can lose more than you planned. The result here assumes the stop fills at its price.
- **Exchanges round down** to a whole number of lots. When you pick a BloFin market, the contract count is rounded that way.

Fees default to 0.05% per fill. Check your own exchange's rate and change it if yours differs.

Crypto and leveraged trading can lose all of your money. This is a calculation, not advice.