Ask a group of long-time traders what kept them in the game, and very few will name an indicator. Most will talk about position sizing: deciding exactly how much to risk before every trade. It is the least exciting part of trading and the one that matters most.
This guide shows the simple lot size formula, worked examples for EUR/USD, USD/JPY and gold, and why the 1% rule protects your account far better than any entry signal.
Key takeaways
- Decide your risk in money first, then calculate the lot size from your stop-loss distance.
- Most disciplined traders risk 0.5%–2% of their account per trade; 1% is a sensible starting point.
- Lot size changes with every trade because stop distances change. The risk amount stays fixed.
- Big losses need much bigger gains to recover, which is why small risk per trade matters.
Lots and pips in one minute
- Standard lot = 100,000 units of the base currency.
- Mini lot = 0.10 lots (10,000 units). Micro lot = 0.01 lots (1,000 units).
- Pip = the fourth decimal place on most pairs (0.0001), or the second decimal on JPY pairs (0.01).
- For pairs where USD is the second currency, such as EUR/USD or GBP/USD, one pip on a standard lot is worth about $10.
The lot size formula
Lot size = (Account balance × Risk %) ÷ (Stop-loss in pips × Pip value per standard lot)
The order matters. You do not choose a lot size and then see what happens. You choose how much you are willing to lose, find the logical place for your stop, and let the formula tell you the size.
Example 1: EUR/USD
- Account: $1,000. Risk: 1% = $10.
- Stop-loss: 25 pips. Pip value: $10 per standard lot.
- Lot size = $10 ÷ (25 × $10) = 0.04 lots.
If the stop is hit, you lose about $10. If your stop needed to be 50 pips instead, the same formula gives 0.02 lots, and the loss is still about $10.
Example 2: USD/JPY
For JPY pairs, the pip value in dollars depends on the exchange rate. At a USD/JPY price of 150.00, one pip on a standard lot is about 100,000 × 0.01 ÷ 150 = $6.67.
- Account: $5,000. Risk: 1% = $50.
- Stop-loss: 30 pips.
- Lot size = $50 ÷ (30 × $6.67) ≈ 0.25 lots.
Example 3: Gold (XAU/USD)
Contract sizes for gold vary by broker, so always check yours. With a common contract of 100 ounces per lot, a $1 move in gold equals $100 per standard lot.
- Account: $10,000. Risk: 1% = $100.
- Stop-loss: $5 away from entry, which costs $500 per standard lot.
- Lot size = $100 ÷ $500 = 0.20 lots.
Why the 1% rule works
Every strategy has losing streaks, even good ones. The table below shows what 10 losses in a row do to an account at different risk levels, and the gain needed afterwards just to get back to where you started.
| Risk per trade | Drawdown after 10 losses | Gain needed to recover |
|---|---|---|
| 1% | 9.6% | 10.6% |
| 2% | 18.3% | 22.4% |
| 5% | 40.1% | 67.0% |
| 10% | 65.1% | 186.8% |
At 1% risk, a bad run is uncomfortable but survivable. At 10%, the same run leaves you needing to almost triple what is left. That is why risk per trade matters more than finding the “perfect” entry.
Risk-reward and win rate
Position sizing works together with risk-reward. If you risk 1R to make 2R, you only need to win more than about one trade in three to break even before costs. Many of our strategies, such as the EMA crossover strategy and the breakout retest, use a minimum 2R target for this reason.
A simple risk plan to copy
- Risk a fixed 1% (or less) on every trade.
- Set a daily loss limit, for example 3%. Stop trading for the day if you hit it.
- Never move your stop-loss further away once the trade is open.
- Be careful with correlated pairs. Buying EUR/USD and GBP/USD together is close to doubling the same bet.
- Account for spreads and commission, especially on short-term trades.
Position sizing mistakes
- Using the same lot size on every trade regardless of stop distance.
- Placing the stop based on how much you want to lose rather than where the trade idea is proven wrong.
- Increasing size after losses to “win it back”.
- Treating leverage as a target. High leverage only allows bigger positions; it does not make them safer.
Position sizing FAQ
What lot size should I use for a $100 account?
At 1% risk you can lose $1 per trade. With a 20-pip stop on EUR/USD that is 0.005 lots, which is below the 0.01 micro lot many brokers allow. Small accounts often need cent accounts, wider-spaced trades, or simply more time on demo while saving more capital.
Is 2% risk per trade too much?
2% is the upper end for many disciplined traders. It is not reckless, but drawdowns come twice as fast as at 1%. Beginners are usually better off at 0.5%–1% while they learn.
Do I need a position size calculator?
A calculator is convenient, but you should understand the formula above so you can check its numbers. Pip values change with exchange rates and account currency.
This article is for education only and is not financial advice. All figures are illustrative examples. Contract sizes and pip values vary by broker and account currency. Trading Forex carries a high risk of loss. Read our Risk Disclaimer.