Last updated: 5 June 2026
A free position size calculator and TradingView indicator. Built by a forex trader, for forex traders, because almost every account I've ever seen blown could have been saved by getting position sizing right.
fxsizecalc.com calculates the exact lot size you should trade based on three inputs: your account balance, the risk percentage you're willing to take on a single trade, and the distance from your entry to your stop loss. It supports every major forex pair, every account currency, and uses live FX rates so the pip value conversion is always correct — even if your account is in GBP and you're trading USD-quoted pairs.
There's also a dedicated prop firm version with presets for the major funded-account providers (FTMO, FundedNext, FundingPips, The5%ers, E8 Markets) and a drawdown headroom panel so you can see at a glance whether your planned trade puts you at risk of breaching the firm's daily loss limit.
Plus a free TradingView indicator that puts the same calculator directly onto your chart — drag the entry and stop lines, the lot size updates live.
Most forex traders lose money. UK and US regulators consistently report retail trader failure rates of 70–80%. Almost none of those traders lose because their analysis was wrong. They lose because one oversized trade undoes a month of disciplined wins, or because they were silently risking more than they intended because they got the pip value calculation wrong on a cross-currency pair.
I built the first version of this calculator for my own trading after blowing too many accounts on sloppy sizing. Once it was working, it seemed obvious that no trader should ever blow an account over basic arithmetic — so the whole thing went online as a free tool.
Nothing. There's no signup, no email capture, no premium tier. The site is monetised through optional affiliate links to prop firms and brokers — but only if you choose to use them. The calculator and the TradingView indicator stay free regardless.
This site does not give trading advice or recommendations. It calculates a number based on the risk parameters you choose. It's a piece of arithmetic, not a strategy.
Position sizing alone won't save you if you're taking poor setups or trading against a higher-timeframe trend. The calculator solves one important problem (how much to risk) — but you still have to bring the rest. There's a longer write-up on this in the complete position sizing guide.
Feedback, bug reports, suggestions, or just a hello: contact@fxsizecalc.com.
If you've spotted a prop firm rule on this site that's out of date, please tell me — I run a monthly audit, but firm rules change quickly and I'd rather hear it from a trader than discover it on the next sweep.