# Position Size Calculator

R-based sizing: risk a fixed % of your account per trade. This calculator converts that risk into the exact position size in both contracts and notional USD, so you never eyeball a position again. For deeper theory see our Kelly risk guide.

Source: https://bykaranteli.com/tools/position-size · attribute to ByKaranteli and quote the timestamp.

## How the math works

- Risk in USD = account_usd × (risk_percent / 100)
- Stop distance = |entry − stop|
- Position (contracts) = risk_usd / stop_distance (rounded down to lot size)
- Notional (USD) = position × entry
- Leverage used = notional / account

Rule of thumb: risk 0.5-1% per trade. Risking 5% means 20 losers in a row and you're down 64% · math does not care about how certain you felt going in.

Hypothetical result. Computed with hindsight from recorded prices or the numbers you entered; fees, slippage and funding only where a field says so; not a forecast, not a trade that was placed and not indicative of future results.

## FAQ

### What is R-based position sizing?

You risk a fixed percentage of your account per trade. The calculator divides that risk in USD by your stop distance to get the exact position size in contracts and notional USD.

### What risk percentage per trade is reasonable?

A common rule is 0.5-1% of the account per trade. Risking 5% per trade means 20 consecutive losses would draw the account down about 64%.

### How is leverage derived here?

Leverage is an output, not an input: notional USD divided by account size. Size comes from risk and stop distance, and the leverage figure just follows.


## Related

- https://bykaranteli.com/tools/liq-calc
- https://bykaranteli.com/tools/funding-arb-calc
- https://bykaranteli.com/tools/dca-backtester
- https://bykaranteli.com/tools/grid-simulator
- https://bykaranteli.com/tools/twap

Everything in one fetch: https://bykaranteli.com/llms-full.txt