What did you get wrong about lot size on your first trade?

Lot size is the amount of currency a trade controls, and it is one of the first things a new trader sets on a platform. A mistake in the lot size can make a trade several times larger than intended, even when the stop and the chart are correct. Leverage and margin explained shows how the lot size, the margin and the amount at risk connect, which is the calculation to check before the first order.

Many members remember the lot size as the mistake that surprised them most on an early trade. The usual error is to confuse a mini lot with a standard lot, or to size from the account balance rather than from the amount they are prepared to lose. A short check before each order, comparing the cash risk with the planned loss, catches most of these errors.

We would like to hear your experience:

• What was your lot size on your first trade, and what did you expect it to risk?
• How did you find out that the size was wrong?
• What check do you run now before you place an order?
• What would you tell a new trader about lot size in one sentence?

Please share your own approach and reasoning, not calls for others to copy. Posts that promise a direction or sell signals will be removed.