What is a lot size?

What it is

A lot is the standardised unit of measurement for the amount of currency you're buying or selling in a forex trade. When you place a trade, you're not just saying "buy EUR/USD" — you're saying "buy X lots of EUR/USD." The lot size determines how much real money is at stake per pip of movement.

How it works

The four lot sizes

Standard lot: 100,000 units of the base currency. On EUR/USD, approximately $10 per pip.
Mini lot (0.1): 10,000 units. Approximately $1 per pip.
Micro lot (0.01): 1,000 units. Approximately $0.10 per pip.
Nano lot (0.001): 100 units. Available on some brokers only.

A worked example

EUR/USD moves 50 pips in your favour. How much did you make?

0.01 lot (micro): 50 pips × $0.10 = $5.00
0.10 lot (mini): 50 pips × $1.00 = $50.00
1.00 lot (standard): 50 pips × $10.00 = $500.00

Same strategy, same market move — the only difference is lot size. This is why lot sizing is inseparable from risk management. Running 1.0 lots on a £500 account is very different from running 0.01 lots.

Why it matters

Lot size is how you translate strategy performance into actual pounds and pence. An EA that averages 50 pips per month sounds the same at 0.01 lots ($5) and 1.0 lots ($500) in terms of pips — but the cash result is entirely different, as is the risk.

Lot sizing is also the primary lever for position sizing and risk management. Rather than running a fixed lot size, many EAs scale their lot size based on account equity — trading larger when the account grows and smaller during drawdowns.

Common misconceptions

Bigger lots don't make you a better trader. Running large lots on a small account is how accounts get blown. Lot size should be proportional to account size and the strategy's expected drawdown.
0.01 lots is not the correct size for everyone. It's the standard for backtesting comparisons. Your actual lot size should be chosen based on your account balance, your risk tolerance, and the EA's characteristics.
Lot sizes vary slightly by broker and pair. The $10-per-pip rule applies to USD-quoted pairs with a standard lot. For other pairs and currencies, the calculation differs slightly.

The Karnek note

Karnek is read-only monitoring for MetaTrader - it watches every account you run, live on one dashboard, and alerts you the moment something stops. It never trades and never asks for a trading password.

See it in Karnek: see how Karnek works.