Lot Size Calculator

How to calculate lot size

Lot size = (account size x risk %) ÷ (pip value per unit x stop in pips)

• Risk amount = account size x risk percentage (for example, 1% of $10,000 is $100).
• Pip value per unit = 0.0001 (or 0.01 for JPY pairs) x the quote-to-account currency rate.
• Units = risk amount ÷ (pip value per unit x stop in pips). Divide by 100,000, 10,000, or 1,000 for standard, mini, and micro lots.

Worked example

With a $10,000 account, risking 1% ($100), a 20-pip stop, a standard pair, and the rate at 1:

• Risk amount = $10,000 x 1% = $100
• Pip value per unit = 0.0001 x 1 = $0.0001
• Units = $100 ÷ ($0.0001 x 20) = 50,000 units
• Lots = 0.5 standard, 5 mini, 50 micro

Five mini lots (or half a standard lot) means each pip is worth $5, so a 20-pip stop costs exactly $100, your planned 1% risk. See the pip math itself in the pip value explained guide.

Standard vs mini vs micro: how the stop distance drives size

The three lot sizes are the same math at different scales: a standard lot is 100,000 units, a mini lot is a tenth of that (10,000), and a micro lot is a hundredth (1,000). Which one you end up trading is decided entirely by your stop distance for a fixed risk amount. A tight stop, say 10 pips, lets a $100 risk fund a full standard lot's worth of pip value; a wide 100-pip stop on the same $100 forces the position down to roughly a tenth of a standard lot, into mini-lot territory.

This is why traders with tight, high-conviction stops tend to size in standard or mini lots, while traders on wider structural stops, or accounts too small to fund a full mini lot at their risk percentage, size in micro lots instead. The lot size is not a preference, it falls out of the formula once the stop and the risk amount are fixed.

How this differs from the position size calculator: the position size calculator sizes stocks, ETFs, and crypto in shares or coins from an entry price and a stop price, because the risk per unit is a direct dollar distance. This calculator sizes forex positions in lots from a stop measured in pips, because forex risk per unit runs through pip value first, using the same pip value calculator engine to convert pips into money before dividing. Use the position size calculator for equities and this one for currency pairs.

When it misleads you

The lot size returned is the size that makes a fill exactly at your stop cost your planned risk. In a fast market, on a weekend gap, or around high-impact news, price can skip past your stop and the realised loss can exceed the plan, especially on illiquid or exotic pairs with wider spreads. The rate field also assumes a snapshot exchange rate: on a cross or a pair not quoted in your account currency, a stale rate will misstate the risk amount, so refresh it when rates move materially. Nothing here checks margin requirements either, so confirm your broker's minimum lot size and margin before sizing at the exact number.

How to use this tool

1. Enter your account size. The total capital in the account you trade with.
2. Set your risk per trade. The percentage of the account you are willing to lose if the stop is hit (often 1 to 2 percent).
3. Enter your stop distance. How far your stop-loss sits from your entry, in pips.
4. Choose the pair type and rate. Standard or JPY pair sets the pip size; the rate converts the quote currency into your account currency (leave at 1 if they match).
5. Read your lot size. The tool returns standard, mini, and micro lots, the exact units, and the dollar amount at risk.

Frequently asked questions

Related tools and guides

• Position Size Calculator
• Pip Value Calculator
• Pip value explained
• Position size calculator guide