How to Calculate Forex Position Size from Your Stop Loss

Forex position size is the number of units or lots you trade. To calculate it, divide your cash risk budget by the estimated loss on one lot if the stop is reached. The stop belongs at the price that invalidates your trade; the lot size then adapts to that distance.

This guide uses hypothetical prices and a USD account. The calculations describe planned risk before trading costs and execution differences, rather than a guaranteed maximum loss.

The forex position sizing formula

First calculate the amount you intend to risk:

Cash risk = account balance × risk percentage ÷ 100

Then calculate lots:

Lots = cash risk ÷ (stop distance in pips × pip value per lot)

For symbols where pip conventions are unclear, use the broker's tick specification instead:

Loss per lot = absolute entry-to-stop distance ÷ tick size × tick value per lot

Check the units carefully. A pip, a quoted point, and a minimum price tick are not necessarily the same. MetaQuotes documents tick size, tick value, and permitted volume increments in its symbol properties reference.

Worked example: EURUSD lot size on a $10,000 account

Assume a trader has a $10,000 balance and chooses a hypothetical risk budget of 0.5%. That makes the cash budget $50. This percentage illustrates the arithmetic; it is not a recommended setting for every account.

Suppose the planned long entry is 1.1000 and the stop is 1.0975. The distance is 0.0025, or 25 pips under the usual EURUSD convention. Assume this broker's standard lot is 100,000 EUR and one pip is worth $10 per lot in this USD account.

Input	Value
Account balance	$10,000
Illustrative risk	0.5%, or $50
Entry / stop	1.1000 / 1.0975
Stop distance	25 pips
Estimated loss on 1 lot	25 × $10 = $250
Calculated volume	$50 ÷ $250 = 0.20 lots

If the stop moves to 1.0950, the distance doubles to 50 pips. Keeping the same $50 budget reduces volume to 0.10 lots. Keeping 0.20 lots would double planned risk.

Round down to the broker's volume step

Suppose a different calculation produces 0.237 lots and the broker accepts steps of 0.01. Rounding down gives 0.23 lots. Rounding to the nearest step would produce 0.24 and exceed the original budget before costs.

If the calculated volume is below the broker's minimum, skip that combination of account, stop, and instrument. Moving the stop closer solely to make the minimum volume fit changes the trade thesis.

Leave room for costs. If estimated commission and other costs consume $4 of a $50 budget, only $46 remains for the entry-to-stop movement. A sizing calculation that ignores costs does not keep total losses within $50. Slippage or a gap can exceed either estimate.

Leverage does not replace position sizing

Margin answers whether the account can support an order. Stop-based risk answers what the planned adverse price move would cost. A broker allowing a larger position does not make that position appropriate for your loss budget.

Pip values can also change with account currency and the instrument. Do not reuse the EURUSD assumption for USDJPY, gold, or an index CFD. For gold, follow the XAUUSD lot size example.

Use TickerAI to check the plan

With a supported connected MT5 account, TickerAI can size an executable idea using the broker's symbol specification and your configured risk limit. It rounds volume down and refuses when the minimum lot cannot fit the budget. The initial idea is still an estimate; execution checks use current account and broker figures.

Ask: “Show the entry, stop distance, cash risk, broker specification, and calculated lots before I consider this trade.” Then compare the numbers with the broker's order screen. Read how TickerAI sizes trades for the product workflow and the pre-trade checklist for the remaining checks.

Educational example only. Trading can lose money, and a stop order does not guarantee its requested execution price.