Forex Risk Calculator & Position Size Calculator

About Forex Position Size Calculator

Use this forex risk calculator before placing a trade to turn a fixed cash-risk limit and planned stop loss into a position size. It shows the resulting base units, lots, pip value, potential loss, target reward and required margin from the rates and contract settings you enter.

Forex Position Size Calculator is a free, browser-based forex position size calculator from ProfitTool. Work out the exact lot size a trade needs so your stop loss costs a fixed percentage of your balance. Shows standard/mini/micro lots, required margin, risk:reward, and the arithmetic behind every figure. Review any usage notes shown on this page before relying on its availability. Review the tool's data-handling notice before entering sensitive information; some features store settings locally or contact external services.

Pairs naturally with the Trading Profit/Loss Calculator — Pip Size & Value Calculator handles the follow-up case.

How to use Forex Position Size Calculator

1. 1Choose the currency your trading account is denominated in, then select the instrument and set its current price and quote-to-account conversion rate. The prefilled rates are only a reference snapshot.
2. 2Enter your account balance, the maximum percentage you are prepared to risk, and the distance from entry to your planned stop loss in pips.
3. 3Set a take-profit distance and leverage so you can compare the potential reward and required margin with the planned loss.
4. 4Use the calculated lot size as a starting point, round it down to your broker's permitted increment, and recalculate after allowing for spread, commission, swap and slippage.

If you came here from the Percentage Calculator, Trading Profit/Loss Calculator covers the other half of the workflow.

Position Size, Pip Value & Required Margin Formulas

Pip size is quoted in the pair's quote currency — 0.0001 for most pairs, 0.01 for JPY crosses — so it must be divided by the quote-per-account-currency rate before it means anything to your balance. That single division is what makes the account currency matter: the same EUR/USD trade sized from a EUR account produces a different unit count than from a USD account, because a euro of risk buys a different number of dollars of exposure. Required margin is derived from notional value, not from the unit count, which is why the pair price appears in it. A formula that divides units by leverage happens to be correct only when the base currency is also the account currency, and understates margin on every other pair.

1. Cash at risk: Risk = Balance × (Risk% / 100)
2. Pip value per unit of base currency: PipPerUnit = PipSize / (Quote per Account)
3. Position size in base units: Units = Risk / (StopLossPips × PipPerUnit)
4. Lots: Lots = Units / ContractSize   (100,000 for spot FX, 100 oz for XAU, 1 coin for BTC)
5. Pip value for the whole position: PipValue = Units × PipPerUnit
6. Notional in account currency: Notional = (Units × PairPrice) / (Quote per Account)
7. Required margin: Margin = Notional / Leverage

Worked Step-by-Step Example

Risk = $5,000 × 1% = $50.00
PipPerUnit = 0.0001 / 1 = 0.0001 USD (quote currency is USD, so no conversion)
Units = $50 / (25 × 0.0001) = 20,000 EUR = 0.20 standard lots
PipValue = 20,000 × 0.0001 = $2.00 per pip
Check: 25 pips × $2.00 = $50.00 — matches the risk budget, so the size is right
Notional = 20,000 × 1.0850 = $21,700
Margin = $21,700 / 100 = $217.00 (4.3% of the balance)
Reward at target = 75 × $2.00 = $150.00, a 1:3 risk-to-reward ratio

Why this matters

Money and health decisions get made on rough mental maths far too often. Running the actual numbers takes thirty seconds and routinely changes the answer — whether that's a loan you shouldn't sign, a rate you should be charging, or a target you can realistically hit.

Popular Use Cases

• Case 1
  Size a major-pair trade from a fixed account-risk percentage and a planned stop loss.
• Case 2
  Convert a pip movement into your account currency when the quote currency differs from your balance currency.
• Case 3
  Compare standard, mini and micro lot sizes with the margin required at your broker's leverage.
• Case 4
  Check the cash loss at the stop and cash reward at a target before submitting an order.

Common Mistakes to Avoid

Working alongside the Pip Size & Value Calculator? Percentage Calculator is the usual next step.

Key Terms Explained

Principal

The original amount borrowed or invested, before any interest is applied.

APR

Annual Percentage Rate — the yearly cost of a loan including fees, which is what makes it comparable between lenders.

Compounding

Earning interest on previously earned interest. Frequency (monthly vs annually) meaningfully changes the total.

Amortisation

The schedule showing how each payment splits between interest and principal over the life of a loan.

Pro Tips & Best Practices

• Replace the reference pair price and conversion rate with the current values from your broker before you trade.
• Use your broker's contract specification and round the result down to its permitted lot increment, then recalculate the risk.
• Allow separately for spread, commission, swap and possible slippage; they are not included in the position-size result.

Frequently Asked Questions

Guides that explain Forex Position Size Calculator

Background reading from the ProfitTool Knowledge Hub.