Lot Size

A lot size is the quantity of a currency pair traded in a single FX transaction. The three standard sizes are a standard lot (100,000 units), a mini lot (10,000 units), and a micro lot (1,000 units). Lot size determines the dollar value of a pip move, the margin required, and the total gain or loss on a trade.

The three standard lot sizes

Standard lot: 100,000 units of the base currency. On EUR/USD, a standard lot is 100,000 euros. If the spot rate is 1.0850, you are controlling $108,500 of value. A 1-pip move is $10. A 100-pip move is $1,000. Standard lots are the default size for institutional traders and some retail traders with substantial capital.

Mini lot: 10,000 units of the base currency. A mini lot on EUR/USD at 1.0850 is worth $10,850. A 1-pip move is $1. A 100-pip move is $100. Mini lots are popular with retail traders managing $10,000–$100,000 accounts. They allow meaningful exposure without catastrophic leverage risk.

Micro lot: 1,000 units of the base currency. A micro lot on EUR/USD at 1.0850 is worth $1,085. A 1-pip move is $0.10. A 100-pip move is $10. Micro lots are for beginners, risk-averse traders, and paper traders learning the markets. They let you place real trades with minimal capital at risk.

How pip value depends on lot size

The pip value formula for non-yen pairs is: Pip value = (Lot size / 100,000) × $10

• Standard lot: 100,000 / 100,000 × $10 = $10 per pip
• Mini lot: 10,000 / 100,000 × $10 = $1 per pip
• Micro lot: 1,000 / 100,000 × $10 = $0.10 per pip

For yen pairs, the formula is slightly different because the yen is quoted to two decimal places, not four. A standard lot on USD/JPY moves $10 per pip (same as non-yen pairs by coincidence, because the smaller yen value is offset by the change in decimal places). A mini lot is $1 per pip; a micro lot is $0.10 per pip.

This is why traders talk about lot sizes obsessively: changing from a standard to a mini lot changes your risk per pip by a factor of 10. This is not a minor adjustment; it is the difference between manageable risk and ruin.

Lot size and margin requirements

Margin requirements scale with lot size. If your broker requires 1% margin (equivalently, 100:1 leverage) on a standard lot of EUR/USD, you need $1,085 to control a $108,500 position. For a mini lot, you need $108.50. For a micro lot, you need $10.85.

This creates a choice: how much capital do you have, and how much risk per trade can you afford? A trader with $1,000 can afford a 10-mini-lot position at 1% margin. A trader with $10,000 can afford a 100-mini-lot position or a 10-standard-lot position. The right choice depends on your risk tolerance and trading plan.

Position sizing and discipline

Professional traders use lot sizes as a risk-management tool. They decide, before placing a trade, how much capital they are willing to lose if the trade goes wrong. If you have a $10,000 account and decide you will not risk more than $100 on a single trade, you can calculate the maximum lot size and the stop-loss level that keeps you within that budget.

This discipline is what separates traders who last from those who blow up. Retail traders who skip this step — who simply buy what feels like a good setup without calculating position size — quickly discover that one bad streak can wipe out months of gains.

See also