Position size calculator: balance, risk and stop into a tradeable lot size
Enter balance, risk percentage and stop distance and get the position size that makes them consistent. Rounds down to your broker's volume step. Runs offline, nothing leaves your browser.
Enter your account balance, the percentage you are willing to risk, and the distance to your stop. The calculator returns the position size that makes those three things consistent. It works offline, uses no live rates, and nothing you type leaves your browser.
The two inputs people get wrong
Pip value per lot. The default of 10 is correct for pairs quoted in US dollars when your account is in dollars: EUR/USD, GBP/USD, AUD/USD and the rest of that family. It is not correct for yen pairs, for gold, or when your account is in another currency. Work out the right figure with the pip calculator and put it here.
Volume step. Your broker will not accept any size you like. Most accept steps of 0.01, so 0.037 is not tradeable. The calculator always rounds down, because rounding up means risking more than you decided.
The arithmetic, if you want to do it by hand
- Balance × risk% = money at risk
- Money at risk ÷ stop in pips = value per pip you can afford
- Value per pip ÷ pip value per lot = position size
- Round down to the volume step
Worked: $2,000 × 1% = $20. $20 ÷ 30 pips = $0.667 per pip. $0.667 ÷ $10 = 0.0667 lots. Rounded down: 0.06 lots, real risk $18.
Why the order matters
This calculation only protects you if the stop comes first. The stop belongs where your reason for the trade stops being true, and the size adapts to it. If you pick a size first and then put the stop wherever that size makes the loss feel comfortable, the stop ends up at a price with no meaning, and it gets hit by ordinary noise. See risk management.
When the answer comes back as zero
On a small account with a wide stop, the calculated size can fall below the minimum step. The calculator says so rather than rounding up. The honest options are a wider account, a tighter stop only if the chart justifies it, or accepting a smaller risk percentage. The dishonest option is trading 0.01 anyway and pretending the risk rule still applies.
Related
- Pip calculator: the pip value input above.
- Risk calculator: same thing from entry and stop prices, with reward to risk.
- Lots and pips.
Frequently asked questions
What do I put in pip value per lot?
10 is correct for pairs quoted in US dollars when your account is in dollars. It is wrong for yen pairs, for gold, and when your account is in another currency. Work the right figure out with the pip calculator first.
Why does it round down instead of to the nearest?
Because rounding up means risking more than you decided. With a 0.01 step, 0.125 lots becomes 0.12, not 0.13. On a small account that difference is a meaningful percentage on every trade.
It says my size is below the minimum step. What now?
The honest options are a wider stop only if the chart justifies it, a smaller risk percentage, or a larger account. Trading 0.01 anyway means abandoning the risk rule while believing you still have one.
More in Tools
- Risk calculator: entry, stop and target into size and reward to risk Works from prices rather than pips. Gives stop distance, position size for your risk percentage, and the reward to...
- Lot size calculator: from money at risk to a size your broker accepts Turn the money you are willing to lose and your stop distance into a lot size, rounded down to the volume step....
- Pip calculator: what one pip is worth for your pair and account Pip value for any pair, position size and account currency, including yen pairs and gold. No live rates, so you...