Forex Position Sizing: The 1% Rule in Pips and Lots

Position sizing means choosing the lot size so that, if your stop-loss is hit, you lose a fixed, small share of your account, often 1% or less. The formula is lot size = (equity × risk %) ÷ (stop distance in pips × pip value per lot). For example, with 2,000 dollars, a 1% risk (20 dollars) and a 40-pip stop on EUR/USD (10 dollars per pip per lot), the right size is 0.05 lot. Getting this right matters more than any entry signal.

Why a fixed percentage

Professional traders usually start with one question: how much am I willing to lose if I am wrong? Expressing that as a percentage of equity has three advantages:

1. Every trade risks the same money, whatever the pair, stop or volatility, so no single trade can do outsized damage.
2. Positions shrink after losses and grow after gains automatically, which slows down drawdowns.
3. Results become comparable in "R", where 1R is the amount risked. A +2R trade made twice what was risked, whatever the pips.

Common choices are 0.5% to 1% per trade for most traders, and up to 2% for those with a long, tested record. Above that, normal losing streaks become dangerous, as Risk of Ruin shows.

The formula, step by step

1. Money at risk = equity × risk %.
2. Stop distance in pips, from your plan (structure or ATR, see Stop-Loss and Risk:Reward). Add the spread.
3. Pip value per lot in your account currency (see What Is a Pip?).
4. Lot size = money at risk ÷ (stop pips × pip value per lot).
5. Round down to your broker's lot step (usually 0.01).

Worked examples (US dollar account, 2,000 dollars, 1% risk = 20 dollars)

Example 1: EUR/USD. Stop 40 pips. Pip value per lot = 10 dollars. Lot size = 20 ÷ (40 × 10) = 20 ÷ 400 = 0.05 lot. Check: 0.05 lot is 0.50 dollars per pip; 40 pips × 0.50 = 20 dollars.

Example 2: USD/JPY at 150.00. Stop 60 pips. Pip value per lot = 1,000 yen ÷ 150 = 6.67 dollars. Lot size = 20 ÷ (60 × 6.67) = 20 ÷ 400 = 0.05 lot. Check: 0.05 × 6.67 = 0.33 dollars per pip; 60 pips × 0.33 ≈ 20 dollars.

Example 3: EUR/GBP with GBP/USD at 1.3000. Stop 30 pips. Pip value per lot = 10 pounds = 13 dollars. Lot size = 20 ÷ (30 × 13) = 20 ÷ 390 = 0.051, rounded down to 0.05 lot. Real risk = 0.05 × 13 × 30 = 19.50 dollars, just under 1%.

Notice that the stops are different in pips but the money at risk is the same. That is the whole point.

Include the spread (and slippage)

Your stop is hit at the bid for a long trade, after you bought at the ask. The spread is therefore part of your loss.

Rounding down gives up a little risk. Rounding up would break your rule; always round down.

If you trade through news or hold over weekends, remember that a stop can slip. Some traders size on a slightly larger "worst case" stop for those trades.

A quick lookup table

Lots needed for EUR/USD (10 dollars per pip per lot) at a given risk in dollars and stop in pips:

Risk ↓ / Stop →	20 pips	40 pips	80 pips	150 pips
10 dollars	0.05	0.02	0.01	below minimum
50 dollars	0.25	0.12	0.06	0.03
100 dollars	0.50	0.25	0.12	0.06
500 dollars	2.50	1.25	0.62	0.33

Values are rounded down to 0.01. For other pairs, scale by their pip value.

The small-account problem

The smallest lot most brokers allow is 0.01 (a micro lot), worth about 10 cents per pip on EUR/USD. That sets a floor on risk:

Honest options:

• Accept that you cannot follow the plan at 1% yet, and paper trade or demo while saving more capital.
• Use a broker that offers nano lots (0.001) or "cent" accounts, after checking its regulation.
• Trade only setups where a tighter stop is genuinely justified, never shrinking the stop just to fit the size.

Do not "solve" it by ignoring the stop. That is how small accounts become empty accounts.

Total risk across open trades

The 1% rule applies per trade. Add a cap on total open risk, for example 3% to 5% of equity across all positions, and treat correlated trades as one (see Forex Correlations). Three 1% trades all short the US dollar are a 3% bet on one idea.

Recalculate as equity changes

Base the calculation on current equity, not your starting deposit. After a 10% drawdown, 1% of a 2,000-dollar account is 18 dollars, not 20. This automatic shrinking is one of the best protections you have. Some traders recalculate weekly rather than every trade to keep it simple, which is fine as long as they do it consistently.

Next: where exactly to put that stop, and how far to aim, in Stop-Loss and Risk:Reward.