Forex
Lot Size Calculator
Calculate forex position size in standard, mini and micro lots from account balance, risk %, stop-loss in pips and pair — with correct JPY pip handling.
Position size
0.2 standard lots
- Risk amount
- $100.00
- Units
- 20,000
- Mini lots
- 2
- Micro lots
- 20
Uses the same pip-size and JPY handling as the pip value calculator.
Worked example
A trader has a $10,000 account, risks 1% per trade, and sets a 50-pip stop on EUR/USD (USD account).
- Risk amount
- $10,000 × 1% = $100
- Pip value per unit
- 0.0001 × 1 (USD/USD) = $0.0001
- Risk per unit
- 50 pips × $0.0001 = $0.005
- Units
- $100 ÷ $0.005 = 20,000 units
- Standard lots
- 20,000 ÷ 100,000 = 0.2 lots
The trader should trade 0.2 standard lots (2 mini lots, or 20 micro lots) — risking exactly $100 if the 50-pip stop is hit.
How this is calculated
This reuses the same pip-size and JPY-handling logic as the pip value calculator: pip size = 0.01 for JPY-quoted pairs, 0.0001 otherwise.
riskAmount = balance × risk%. Dividing by stopLossPips × pipValuePerUnit (in your account currency) gives the number of units to trade, which we then express as standard (100,000), mini (10,000) and micro (1,000) lots.
Common mistakes
- Using the wrong pip size for JPY pairs (0.01, not 0.0001), which overstates position size by 100x.
- Forgetting to convert pip value into the account currency on cross pairs, sizing the position incorrectly.
- Rounding lot size up instead of down — rounding up increases risk above the intended %.
Frequently asked questions
- How is lot size calculated?
- Units = risk amount ÷ (stop-loss pips × pip value per unit), where pip value per unit already accounts for JPY pip size and currency conversion.
- What is a standard, mini and micro lot?
- A standard lot is 100,000 units, a mini lot is 10,000 units and a micro lot is 1,000 units of the base currency.
- Does this work for JPY pairs?
- Yes — it reuses the same pip-size logic as the pip value calculator (0.01 for JPY-quoted pairs, 0.0001 otherwise), so JPY pairs size correctly.
- What conversion rate should I use?
- The current rate between the pair's quote currency and your account currency — use 1 if they're the same currency.
- Why is my broker's minimum lot size different from my calculated size?
- Brokers often only allow lot sizes in fixed increments (e.g. 0.01 lots); round down to the nearest allowed increment to stay within your risk %.
- How does this relate to the position size calculator?
- Same underlying idea — risk amount ÷ per-unit risk — but expressed in forex-specific pip terms and lot sizes instead of raw price distance.