Position size calculator for forex, gold and indices

Position size is the money you accept to lose divided by what one lot loses at your stop, rounded down to your broker’s volume step. With a $5,000 balance, 1% risk and a 25-pip stop on EURUSD, that is $50 ÷ $250 = 0.20 lot.

The calculator above does this for 28 currency pairs, gold, silver, four index CFDs and bitcoin, in 16 account currencies. It shows the loss at the stop after rounding, what rounding up would cost instead, and your stop read back in pips, points and price, so a typing slip shows up before it costs anything.

How it works

1. Money at risk. A share of your balance (1% of $5,000 is $50) or a fixed amount.
2. Loss per lot. The stop distance in price, times the contract size, converted into your account currency. Commission and spread are added if you enter them under Advanced.
3. Lots. Money at risk divided by the loss per lot, rounded down to the volume step and capped at the maximum volume. Below the minimum volume the answer is 0, never the minimum.

If the instrument is quoted in a currency other than your account’s, one exchange rate converts it. The calculator shows that rate with its date (the ECB reference rate) and lets you type today’s price instead.

The position size formula

money at risk = balance × risk %
loss per lot  = (stop distance + spread)
                × contract size
                × conversion rate
                + commission per lot
lots          = money at risk ÷ loss per lot
                (rounded down to the step)

The same loss per lot can be read straight from MT5: (stop distance ÷ tick size) × tick value. The pip value calculator shows the value of one pip for any lot size.

Worked examples

All four use the same made-up account: $5,000 in USD, risking 1% ($50) per trade.

Gold pips and index points

Gold: $0.01 or $0.10 per pip

Most brokers quote gold to two decimals in MT5, so its smallest step (a point) is $0.01; the Digits field in the symbol’s Specification says for sure. Some brokers, calculators and courses call $0.01 a pip, others call $0.10 a pip. The calculator shows which one it uses and lets you switch. The switch changes the pip count, never the lot size, because the stop in dollars stays the same.

Index CFDs: $1 or $10 per point

An index CFD’s contract size is what a 1-point move is worth on 1.00 lot. Brokers set it per symbol: on NAS100 and US30, 1 and 10 are both common, and some brokers use other values. No default fits every broker, so the calculator asks you to pick it. In MT5 it is the Contract size in the symbol’s Specification window. Check the Volume step there too: some brokers trade indices in steps of 0.1 or 1 lot rather than 0.01, which you can set under Advanced.

Why the lot size is rounded down

Rounding up breaks the risk you set. At 0.07 lot the gold example above loses $52.50, not $50. The calculator rounds down and shows the rounded-up figure separately, so you can see the difference.

When even the minimum lot is too large, the answer is 0 with a warning. Skip the trade rather than raise the risk. A trade that asks for more than the maximum volume is capped, and it then risks less than you set.

Common mistakes

• Points typed as pips. On 5-digit pricing one pip is 10 points. A “250-pip” stop that was really 250 points gives a lot size ten times too small. Check the echo line under the stop.
• The wrong conversion rate. A stale or inverted rate mis-sizes every cross and every non-USD account. The rate used is always shown.
• Ignoring costs. Commission and a spread counted against the stop make each lot lose more, so the right size is smaller.
• Related trades. Two trades on EURUSD and GBPUSD at 1% each can both hit their stops on the same move in the dollar, which is a 2% loss.
• Treating the stop as a guarantee. Gaps and slippage can close a trade beyond its stop, so the real loss can be larger than calculated.

How PipWarden handles this

PipWarden sizes every order the same way, with your broker’s exact values instead of textbook ones. It sizes from your risk per trade, as a share of equity, using the tick size, tick value and volume step that MT5 reports for the symbol. It rounds down, and it skips a trade that would need less than the minimum lot rather than raising the risk. Your limits are checked before every order.

Those checks happen when an order is placed. Open trades run to their own stops, and gaps or slippage can make a loss larger than planned. PipWarden runs inside MT5 on a Windows PC or VPS, with a broker that allows Expert Advisors; it does not run on a phone. See how it works, the features and which brokers work, and read the risk disclosure before trading.