How to use the lot size calculator
The calculator opens with a common setup: a $10,000 account, 1% risk per trade and a 30 pips stop on EUR/USD.
- Account balance and currency. Enter the balance in the currency your broker reports. If you already have open trades, the equity is the better figure, because it includes their open profit or loss.
- Risk per trade. Choose a percentage of the balance or a fixed amount. This is what you lose if the stop-loss is hit, not the margin and not the position size.
- Stop-loss distance in pips. Measure from your planned entry to your stop. MetaTrader shows distances in points, which are tenths of a pip, so 300 points is 30 pips.
- Currency pair, and a price if asked. When the pair’s quote currency differs from your account currency, the form asks for one current price, named on the label (for example the USD/JPY price), so the pip value can be converted.
The results show the position in lots, rounded down to the 0.01-lot step most brokers use, together with the exact size, the equivalent in units, mini and micro lots, and the actual risk after rounding. The table and chart show how the size changes with the stop distance at the same risk.
The position size formula
Position sizing works backwards from the loss you accept:
Lots = Risk amount ÷ (Stop in pips × Pip value per standard lot)
Units = Lots × 100,000The pip value per standard lot is in your account currency: $10 for any pair quoted in dollars in a dollar account, and a converted figure for other pairs. Gold uses 100 ounces per lot and silver 5,000 ounces.
The calculator then rounds the lots down to two decimals and recalculates the actual risk:
A worked example
A $10,000 account risking 1% has $100.00 to lose on the trade. With a 30 pips stop, each pip can cost at most $3.33.
One standard lot of EUR/USD is worth $10.00 per pip, so the exact size is 0.3333 lots. Rounded down, the position is 0.33 lots: 33,000 euros, or 33 micro lots.
Each pip on that position is worth $3.30, so if the stop is hit the loss is $99.00, slightly under the $100.00 limit.
The same risk on USD/JPY at 150 gives 0.50 lots, because a pip on a standard lot there is worth only $6.67. On EUR/GBP with GBP/USD at 1.27, a pip is worth $12.70 per lot and the size falls to 0.26 lots. For a euro account trading EUR/USD at 1.1, the pip value converts to €9.09 and the size is 0.36 lots.
Risk percentage and stop distance
The two inputs that move the answer most are the percentage you risk and the width of the stop. For the same $10,000 account on EUR/USD:
| Risk per trade | Stop | Lot size | Loss if stopped |
|---|---|---|---|
| 0.5% | 30 pips | 0.16 lots | $48.00 |
| 1% | 30 pips | 0.33 lots | $99.00 |
| 2% | 30 pips | 0.66 lots | $198.00 |
| 1% | 15 pips | 0.66 lots | $99.00 |
| 1% | 60 pips | 0.16 lots | $96.00 |
Halving the stop doubles the position, and the loss in money stays the same. That is the point of sizing from risk: the stop goes where the chart says it should, and the position size adjusts to it, rather than the other way round. A trader who uses the same lot size on every trade is in effect risking a different amount each time.
Many traders keep risk per trade between 0.5% and 2%, though there is no single correct figure. The trade-off is drawdown: at 1% per trade, ten losses in a row cost about 9.6% of the account; at 5% per trade they cost about 40%, and recovering from that needs a 67% gain.
Lots, units, mini and micro lots
Brokers express size in different ways, and the calculator shows all of them so you can type the number your platform expects.
- Standard lot: 100,000 units of the base currency (the first currency in the pair). Shown as 1.00.
- Mini lot: 10,000 units, 0.10 lots.
- Micro lot: 1,000 units, 0.01 lots, the smallest size at most brokers.
- Units: some platforms, including many US brokers, take the order in units instead of lots. 0.33 lots lots is 33,000 units.
Gold and silver differ. In the calculator a gold lot is 100 ounces with a $0.10 pip, so 1% risk with a 50 pips stop gives 0.20 lots lots, or 20 ounces. Brokers vary here more than on currencies; check the contract size in your platform’s symbol specification.
Small accounts and the 0.01-lot minimum
With a $500 account, 1% risk and a 30 pips stop, the exact size is 0.0167 lots. Rounded down that is 0.01 lots, which risks only $3.00, or 0.60% of the account.
Widen the stop to 100 pips and the exact size drops to 0.0050 lots, below the smallest order most brokers accept. The calculator then shows 0.00 lots lots and warns you: a single micro lot would risk $10.00, which is 2% of the account. The options are to accept the larger risk, use a tighter stop, wait for a better entry, or use a broker that offers smaller units.
Fixed-amount risk
If you prefer to risk a set sum, choose Fixed amount. Risking $250 with a 25 pips stop on EUR/USD gives exactly 1.00 lots. A fixed amount keeps the money at risk constant as the account grows or shrinks, while a percentage scales it automatically: smaller after losses, larger after gains.
What this calculator does not include
- Spread and slippage. A stop can fill a few pips beyond its level in fast markets or over a weekend gap, so the real loss can exceed the planned one. Some traders add the spread to the stop distance to allow for it.
- Commission. Accounts that charge a commission per lot lose that on top of the stop.
- Changing conversion rates. For pairs that need a conversion price, the pip value moves as that rate moves while the trade is open.
- Margin. The calculator does not check whether you have enough free margin for the position; the margin calculator does that.