Automatic FX Lot Size Calculator
Calculate pip value and risk-based lot size from currency pair, account currency, market rate, stop distance and risk percentage.
Conversion rate means quote-currency to account-currency conversion. Use 1 when they are the same currency.
How to use the Automatic FX Lot Size Calculator correctly
Calculate pip value and risk-based lot size from currency pair, account currency, market rate, stop distance and risk percentage. This page is designed to show not only a result but also the assumptions that drive it. The output is an educational calculation, not a trade signal, and should be checked against the current contract specification of your own broker before an order is placed.
Key inputs
The main inputs on this page are Account Balance, Risk (%), Currency Pair, Account Currency, Current Pair Rate, Required Conversion Rate, Stop Distance (pips). Contract size, minimum volume, lot step, pip/point convention, margin method and account-currency conversion may differ even when two brokers use the same symbol name.
Formula
pip value = contract size × pip size × quote→account conversion; lots = risk money ÷ (stop pips × pip value)This version is useful when account currency differs from the pair quote currency because it exposes the conversion step. Leverage and margin should be treated as capital constraints; they do not replace a cash-loss budget based on the planned stop.
Worked example
If risk money is 100, stop is 20 pips and converted pip value is 10 per lot, the raw size is 0.50 lot.
The example is intentionally simple so the arithmetic can be checked by hand. For a real position, replace every assumption with the values shown in your platform and include costs that are material for your holding period.
How to interpret the result
Use the result together with account-level limits: planned cash risk, required margin, effective leverage, and risk already open in other positions. A mathematically valid maximum is not the same thing as a prudent trade size.
Common mistakes
- Mixing pips, points and whole price units.
- Using a contract size copied from a different broker.
- Ignoring spread, commission, financing or currency conversion.
- Rounding a raw position size up instead of down to the permitted lot step.
FAQ
Can I send the calculated value directly as an order?
Use it as a reference only. Verify contract size, minimum volume, margin rate, account-currency conversion, spread and commission, then round conservatively to a valid order size.
Does higher leverage automatically make the position safer?
No. Higher available leverage generally lowers required margin. It does not reduce the profit or loss created by the same position size and price move.
Why can MT5 or another calculator show a different number?
Differences usually come from symbol specifications, conversion rates, pip/point definitions, rounding rules or whether trading costs are included. Compare the inputs before comparing the final number.
Content reviewed: 2026-08-31