Forex Lot Size Calculator: How to Work Out Position Size (2026)

Short answer: lot size = (account balance × risk %) ÷ (stop-loss in pips × pip value per lot). A $5,000 account risking 1% with a 25-pip stop on EURUSD trades 0.20 lots. You can run the numbers instantly in our free lot size calculator — no sign-up.

Position sizing is the one part of trading where the correct answer is arithmetic, not opinion. This guide gives you the formula, the pip values you need, worked examples for forex, gold and indices, and the mistakes that quietly turn a 1% risk into a 4% one.

What a lot actually is

A lot is the contract size of a trade. In forex it is defined in units of the base currency:

Name	Lots	Units	Typical pip value*
Standard lot	1.00	100,000	$10.00
Mini lot	0.10	10,000	$1.00
Micro lot	0.01	1,000	$0.10

*On a pair quoted in USD, such as EURUSD or GBPUSD. Pairs quoted in another currency need a conversion — more on that below.

The position size formula

Every position-size calculation is the same three inputs:

1. Risk amount — how much money you are willing to lose if the stop is hit. Usually a percentage of balance or equity.
2. Stop distance — how far the stop-loss sits from entry, in pips or in price.
3. Pip value per lot — what one pip is worth on that instrument, for one full lot.

Put together:

Lots = Risk amount ÷ (Stop distance in pips × Pip value per lot)

Notice what the formula does not contain: leverage, margin, or your broker's maximum lot. Leverage decides whether the trade is allowed; it has nothing to do with how much you lose if the stop is hit. Confusing the two is the most common sizing error there is.

Worked example: EURUSD

• Balance: $5,000
• Risk: 1% = $50
• Stop: 25 pips
• Pip value: $10 per standard lot

Lots = 50 ÷ (25 × 10) = 0.20 lots.

If the stop widens to 50 pips and the risk stays at $50, the size halves to 0.10 lots. That is the whole discipline in one line: the risk stays fixed and the size moves, never the other way round.

Worked example: gold (XAUUSD)

Gold trips people up because it is quoted in dollars per ounce, not in pips of a currency. One standard lot of XAUUSD is 100 ounces, so a $1.00 move in the gold price is worth $100 per lot.

• Balance: $10,000
• Risk: 1% = $100
• Stop: $4.00 of gold price (e.g. entry 2,400.00, stop 2,396.00)

Lots = 100 ÷ (4.00 × 100) = 0.25 lots.

Many brokers show gold with two decimals and call $0.10 one pip, which makes it $10 per pip per lot. Both routes give the same answer as long as you are consistent about which unit your stop is measured in. If you trade gold, it is also worth reading how the same maths interacts with funded-account limits in our prop firm guide.

Worked example: indices and crypto

Index and crypto CFDs use a contract size rather than a pip value. Check the instrument specification in MetaTrader (right-click the symbol, Specification) and read Contract size and Tick value. Then:

Lots = Risk ÷ (Stop distance in points × Tick value per lot)

On US30 with a tick value of $1 per point per lot, a $200 risk and an 80-point stop gives 200 ÷ (80 × 1) = 2.50 lots. The formula never changes — only where you read the pip or tick value from.

When your account is not in USD

Pip value is expressed in the quote currency. On EURUSD that is USD; on EURGBP it is GBP; on USDJPY it is JPY. If your account is denominated in something else, the pip value has to be converted before the lot size means anything.

This is where most free calculators quietly guess. They hard-code a rate, or use one that was fetched at some point and never refreshed — and a 3% stale conversion rate means you risk 3% more than you thought, on every trade, forever. Our calculator asks you for the rate when the currencies differ rather than inventing one. It is one extra field, and it is the difference between a number you can trust and a number that looks right.

Five sizing mistakes worth avoiding

1. Sizing by leverage. "1:500 leverage so I can take 5 lots" is a margin statement, not a risk statement. Size from the stop.
2. Fixed lots with variable stops. Trading 0.50 lots on both a 10-pip and a 100-pip stop means your real risk swings by 10×.
3. Ignoring spread and commission. A 10-pip stop with a 2-pip spread is a 12-pip loss. On tight stops this is a large percentage error.
4. Risking on balance while the account is in drawdown. Sizing from equity rather than balance makes losing streaks self-limiting.
5. Rounding up. 0.27 lots rounded to 0.30 is an 11% risk increase. Round down.

Sizing across several accounts at once

If you run more than one account — a personal one and a funded one, say — the correct lot size is different on each, because the balances differ. Doing that by hand on every trade is where mistakes creep in.

This is exactly what risk-based copying is for: our free MT4/MT5 trade copier can size each copied trade by risk percentage, so the same signal is 0.20 lots on a $5,000 account and 2.00 lots on a $50,000 one, calculated from each account's own equity at the moment the trade opens. The formula above still governs it — the software just applies it per account, every time, without you doing arithmetic mid-trade.

Check the maths on your own history

Sizing correctly going forward is one half. The other is finding out whether you have been sizing correctly up to now. Drop a MetaTrader report into the free statement analyzer and look at the spread of your losing trades: if they vary wildly in money terms, your position sizing is not doing its job, whatever the formula on paper says. Our guide to trading performance metrics explains what the rest of those numbers mean.

Try it

The CopyConnectFX lot size calculator is free, needs no account, and runs entirely in your browser — nothing you type is sent to a server. It covers forex, metals, indices and crypto, and asks for the conversion rate instead of assuming it.