In one sentence
The standard unit of trade size in forex: one standard lot is 100,000 units of the base currency, a mini lot is 10,000 and a micro lot is 1,000.
Lot sizes exist so that size can be talked about without quoting raw unit counts. A 0.05 lot EUR/USD position is 5,000 euros of exposure. Most retail traders on small accounts work in micro and mini lots, and the ability to trade 0.01 lots is one of the practical reasons a broker suits a beginner.
Some brokers also offer cent accounts, where the same number means one hundredth of the usual size. Useful for learning with real money; confusing if you forget which account you are in.
The mistake it causes: typing a lot size by habit instead of calculating it, which makes risk per trade a lottery.
The three standard sizes
| Name | Lots | Units | Pip value on USD pairs |
|---|
| Standard | 1.00 | 100,000 | $10.00 |
| Mini | 0.10 | 10,000 | $1.00 |
| Micro | 0.01 | 1,000 | $0.10 |
Most brokers accept 0.01 as the minimum step. That matters more than it sounds: on a small account with a wide stop, 0.01 lots can still be too large, which forces either a tighter stop than the chart justifies or a skipped trade.
Cent accounts, and why they are useful
A cent account multiplies everything by one hundredth, so one lot is 1,000 units rather than 100,000. HFM and XM both offer a version. For a $100 to $300 account it is the difference between sizing correctly and being forced into positions the balance cannot support, which is the most common way a small account dies in its first month.
The risk is forgetting which account you are in. The numbers look identical and the exposure differs by a factor of a hundred.
Round down, never up
Rounding 0.047 to 0.05 adds about 6% to the risk you chose. Done on every trade, that becomes a risk setting you never decided on, and it compounds in exactly the direction you do not want.
What to do with this
- Check the minimum lot step before opening an account with a small balance.
- Calculate the size every time with the position size calculator.
- Confirm the account type on the platform before the first trade of every session.
