Lot step rounding on small accounts

[Amanhasnoname]

Brokers set a minimum lot size and a step, such as 0.01 with steps of 0.01. A position size calculated as 0.037 lots gets rounded to 0.03 or 0.04, depending on the platform.

That rounding changes the risk per trade. On a small account, 0.01 lots might represent a large part of the intended risk. A calculation giving 0.014 and rounding to 0.01 means the risk is 30 percent lower than planned. Rounding up has the opposite effect.

Across many trades, the effect can bias the results. Systematic rounding down reduces average risk, rounding up increases it.

A good practice is rounding down in the position size calculation, so the actual risk never exceeds the plan. Some accept the slight under-sizing as a safety margin.

Another aspect is the pip value per lot on different pairs, which affects how fine the sizing can be.

Checking the symbol specifications for each pair avoids surprises.

How is rounding handled in position sizing, and has it ever distorted the risk?