XAUUSD Position Sizing: How to Calculate Your Lot Size

Every trade review I do starts in the same place, before I even look at the chart: is the position sized to the stop? Not “does the setup look good.” That comes later. If the size is wrong, nothing else about the trade matters yet.

The formula

For XAUUSD, gold moves in a contract where one standard lot (100 oz) is worth $10 per pip. That one number is the whole formula:

• Risk in dollars = account size × risk % per trade
• Lots = risk in dollars ÷ (stop distance in pips × $10)

That’s it. Two inputs you choose (account size, risk %), one input the market gives you (where your stop actually needs to sit), and the answer falls out the other end. You don’t pick a lot size and hope. You calculate it.

A worked example

Say you’re running a $1,000 account and risking 1% per trade, that’s $10 on the line. Structure says your stop needs to sit 100 pips from entry to sit below the level that actually invalidates the trade. Lots = $10 ÷ (100 × $10) = 0.01 lots. That’s the whole calculation, and you don’t have to do it by hand: the calculator on this site runs the exact same formula for you, free.

Why the order matters

The mistake I see most isn’t bad math. It’s doing the steps backwards. Traders decide how many lots “feels right,” then work out where the stop has to go to make that size survivable. That’s sizing the stop to the position instead of the position to the stop, and it means your stop is no longer sitting where the structure says it should. It’s sitting wherever your account size forced it. You’ll get stopped out of trades that were actually right, on levels that never meant anything technically.

Size to the stop, never the other way around. If the position size that comes out feels too small to be worth the trade, the answer is a bigger account or a tighter stop from a cleaner entry, not a bigger position.

What this doesn’t cover

This math is XAUUSD-specific. The $10-per-pip constant only holds for the standard 100 oz gold contract. Indexes, crypto, and stocks all size differently, since contract specs vary by broker and instrument, so that’s worked out with students directly, not through this calculator. The principle doesn’t change though: size to the stop, always.