Academy · 14 November 2026 · 12 min

How to Calculate Lot Size in Trading: Formula and Examples

Forex lot size formula based on your risk and stop loss, with worked examples on EUR/USD, USD/JPY, EUR/GBP, gold, the DAX, BTC and stocks, plus prop firm rules.

To calculate lot size in trading you need three inputs: your account balance, the percentage you are willing to lose on the trade and the distance to your stop loss. Plug them into the formula and it tells you how many lots (or shares, or contracts) you can open without an ordinary loss knocking you out of the game.

This guide explains the position size formula from scratch, with worked examples (EUR/USD, USD/JPY, EUR/GBP, gold, the DAX, BTC and a stock), the prop firm case, a reference table and the mistakes that cost traders the most. If you would rather not do the math by hand, our position size calculator does the same calculation in seconds.

What is position size in trading?

Position size is the quantity of an asset you buy or sell in a trade: lots in forex, ounces in gold, shares in equities or contracts in futures. It is calculated from the maximum risk you accept per trade and the distance to your stop loss, not from how confident you feel.

It is the most neglected part of risk management. Two traders can take the same trade, with the same entry and the same stop, and one loses 1% of the account while the other loses 8%. The only difference is the lot size. That is why position sizing, more than strategy, decides how long an account survives.

Standard, mini and micro lots

In forex, size is measured in lots. A standard lot is 100,000 units of the base currency; most brokers allow fractions down to 0.01 lots.

The position size formula

The general formula works in any market:

Position size = Amount at risk ÷ (Stop distance × Value of each unit of movement)

In forex it reads: lots = amount at risk ÷ (stop in pips × pip value per lot). Each part has a job:

• Amount at risk: account balance × risk percentage. With $10,000 and 1%, that is $100.
• Stop in pips: the distance between entry and stop loss. The chart sets it (a support level, a previous high, volatility), never the amount you want to make.
• Pip value per lot: how much you gain or lose per pip on one standard lot, expressed in your account currency.

How to calculate pip value

A pip is the fourth decimal place on almost every pair (0.0001) and the second decimal place on yen pairs (0.01). Pip value per standard lot is 100,000 × pip size, and the result is in the quote currency (the second currency in the pair).

• Pairs ending in USD (EUR/USD, GBP/USD, AUD/USD): 100,000 × 0.0001 = $10 per pip. If your account is in dollars, no conversion is needed.
• Yen pairs (USD/JPY, EUR/JPY): 100,000 × 0.01 = ¥1,000 per pip. To convert to dollars, divide by the USD/JPY rate.
• Euro account: if a pip is worth $10 and EUR/USD trades at 1.10, the pip is worth 10 ÷ 1.10 = €9.09.

Pip value moves with price, so on crosses or with an account in another currency it is worth checking before every trade. Our pip value calculator does it at the live rate.

How to calculate lot size step by step

1. Set your risk per trade. A fixed percentage of the account, usually between 0.5% and 2%.
2. Turn that percentage into money. Balance × percentage.
3. Place your stop on the chart and measure the distance in pips from entry.
4. Find the pip value per standard lot in your account currency.
5. Apply the formula and always round down to your broker's minimum increment (0.01 lots at most brokers).
6. Check the margin the position requires before you open it.

Worked position size examples

Example 1: EUR/USD with a dollar account

A $10,000 account, 1% risk and a 25-pip stop.

• Amount at risk: 10,000 × 0.01 = $100.
• Pip value per lot: $10.
• Lots: 100 ÷ (25 × 10) = 100 ÷ 250 = 0.40 lots.

Check: if the stop is hit, you lose 25 pips × $4 per pip (0.40 × $10) = $100, exactly 1% of the account.

Example 2: USD/JPY, where pip value changes

Same account and same risk ($100), a 40-pip stop and USD/JPY trading at, say, 150.00.

• Pip value per lot: ¥1,000 ÷ 150 = $6.67.
• Lots: 100 ÷ (40 × 6.67) = 100 ÷ 266.8 = 0.3748, rounded down to 0.37 lots.

Check: 40 pips × 0.37 × $6.67 = $98.72 ($98.67 without rounding the pip value). It lands slightly below $100 because of rounding, which is exactly what you want.

Example 2b: euro account and a cross pair (EUR/GBP)

With a euro account, the EUR/USD calculation changes: if EUR/USD trades at 1.10, a pip is worth €9.09 per lot, and with €100 at risk and a 25-pip stop you get 100 ÷ (25 × 9.09) = 0.44 lots.

On EUR/GBP a pip is worth £10 per lot (sterling is the quote currency). If EUR/GBP trades at, say, 0.85, each pound is worth 1 ÷ 0.85 = €1.1765, so a pip is worth 10 ÷ 0.85 = €11.76. With €100 at risk and a 30-pip stop: 100 ÷ (30 × 11.76) = 0.283, rounded to 0.28 lots. Check: 30 × 0.28 × 11.76 = €98.78.

Example 3: gold (XAU/USD)

At most brokers one lot of gold is 100 ounces, so every dollar the price moves is worth $100 per lot. This contract size is not universal: check the specifications on your platform.

• $10,000 account, 1% risk = $100.
• Stop $8 away from entry.
• Lots: 100 ÷ (8 × 100) = 100 ÷ 800 = 0.12 lots (0.125 rounded down).

Example 4: shares

In equities the formula uses shares instead of lots. A €20,000 account, 1% risk (€200), a buy at €50 and a stop at €47.

• Risk per share: 50 − 47 = €3.
• Number of shares: 200 ÷ 3 = 66.67, so 66 shares.
• Capital invested: 66 × 50 = €3,300. Loss if the stop is hit: 66 × 3 = €198.

Note that investing €3,300 does not mean risking €3,300. The real risk is the stop distance multiplied by the size.

Example 5: an index (DAX)

With index CFDs the value per point depends on each broker's contract. If your broker sets €1 per point per lot, with a €10,000 account, 1% risk (€100) and a 40-point stop: 100 ÷ (40 × 1) = 2.5 lots. If the contract is worth €25 per point, the same risk gives 0.10 lots.

Example 6: crypto (BTC)

If one BTC/USD lot at your broker equals 1 bitcoin, each dollar of movement is worth $1 per lot. With $100 at risk and a stop $1,500 from entry: 100 ÷ 1,500 = 0.0667, so 0.06 lots if the minimum is 0.01. For crypto CFDs offered to retail clients in the EU, leverage is capped at 2:1, so margin weighs far more than in forex.

Same trade, different stop: how lot size changes

The amount at risk stays fixed and the size adjusts to the stop. With $100 at risk on EUR/USD:

The hidden cost: spreads and commissions

You pay the spread on entry, so the real distance to the stop is the chart distance plus the spread. With a 10-pip stop and a 1-pip spread, the real loss if the stop is hit is 11 pips: 10% more than calculated. With a 50-pip stop, that same pip adds only 2%. The tighter the stop, the more it pays to add the spread and commission to the distance before applying the formula.

How much of your account should you risk per trade?

A common benchmark in risk management is to risk between 0.5% and 2% of capital per trade, with 1% the most usual starting point. It is not a law: it is a way of making sure a losing streak, which sooner or later arrives, does not destroy the account.

The table shows what is left of a $10,000 account after several consecutive losses, recalculating the risk on the remaining balance:

At 1%, twenty straight losses leave the account down 18%. At 5%, the same streak wipes out almost two thirds of the capital, and recovering from a 64% drawdown requires a 179% gain. You can simulate your own streaks with the drawdown calculator.

Position size, leverage and margin

Leverage does not change how much you lose if the stop is hit; position size decides that. What it changes is the margin, the money your broker sets aside to keep the trade open. High leverage simply lets you open positions larger than your capital could pay for in cash.

In the European Union, ESMA capped CFD leverage in 2018 for retail clients: 30:1 on major currency pairs, 20:1 on non-major pairs, gold and major indices, 10:1 on commodities other than gold and non-major indices, 5:1 on individual shares and 2:1 on cryptocurrencies. It also introduced margin close-out when margin falls to 50% of the required minimum, plus negative balance protection. Those limits now apply permanently through each country's national rules.

In example 1, 0.40 lots of EUR/USD is €40,000 (the base currency). With EUR/USD at 1.10, the notional value in the account currency (dollars) is $44,000, and at 30:1 leverage the required margin is 44,000 ÷ 30 = $1,466.67. That is money set aside, not money at risk. To work it out for your broker and pair, use the margin calculator.

Fixed lot size vs fixed risk: same streak, two outcomes

This is the calculation that explains why so many accounts blow up without a bad strategy. Imagine five consecutive losses on EUR/USD with stops of 20, 40, 60, 80 and 80 pips, which is normal if the stop adapts to volatility, on a $10,000 account.

Entries and stops are identical. The only difference is whether size adapts to the stop. With a fixed lot size, the biggest losses arrive precisely when the stop is widest, which tends to coincide with the most volatile moments.

Position sizing at a prop firm

On funded accounts (prop firms) position size has an extra ceiling: the maximum daily loss and the overall drawdown. The figures vary by firm; a common structure is a 5% daily loss limit and a 10% total loss limit. On a $100,000 account with those rules, risking 1% per trade ($1,000) means five straight losses in one day hit the limit, and with commissions or slippage they breach it. At 0.5% ($500) it would take ten. The real buffer depends on how each firm calculates the daily loss: on balance or on equity, and whether it includes floating losses on open trades. Read their rules before setting your risk.

The practical rule is to size each trade with the daily limit in mind, not the balance, and to count open trades that could close at a loss at the same time. You can see how real accounts manage risk in our directory of audited traders.

Common lot size mistakes

• Placing the stop where the money fits. If you force a 10-pip stop so you can trade 1 lot, the market will hit it on noise. Technical stop first, size second.
• Always trading the same lot size. With a fixed 0.50 lots, a 20-pip stop risks $100 and an 80-pip stop risks $400. Risk should be fixed; lot size should vary.
• Forgetting your account currency. On yen pairs or crosses a pip is not worth $10. With USD/JPY at 150, using $10 instead of $6.67 means you open 0.25 lots on a 40-pip stop and risk $66.70 instead of $100: 33% less than planned. On pairs where a pip is worth more than $10, the error runs the other way and you over-risk.
• Mixing up pips and pipettes. MT4 and MT5 quote to five decimals (three on yen pairs). The fifth decimal is a pipette, a tenth of a pip: a "50-point" stop on the platform is 5 pips, not 50. Confusing them multiplies or divides your lot size by ten.
• Stacking correlated trades. Buying EUR/USD and GBP/USD at the same time with 1% on each is a lot like risking 2% on a single idea. Check the currency correlation.
• Ignoring slippage and gaps. Around high-impact news or the Monday open your stop can fill at a worse price. Trading smaller on those days is a risk management decision, not cowardice.
• Raising risk to win it back. Doubling size after a loss is the fastest way to turn a bad run into a blown account.

Checklist before you open a trade

1. Do I know exactly where my stop goes and why?
2. Have I calculated the amount at risk on my current balance, not the starting one?
3. Have I used the correct pip value for this pair and my currency?
4. Have I rounded the lot size down?
5. Do I have enough margin, and am I within my total risk once open trades are added up?
6. Is there major news in the next few hours that could cause gaps?

Summary table

Trading CFDs and leveraged forex carries a high risk of losing money rapidly. Before you trade, read our risk warning.

Frequently asked questions

How many lots can I trade with $1,000?

It depends on the stop, not just the capital. With 1% risk ($10) and a 20-pip stop on EUR/USD, the calculation is 10 ÷ (20 × 10) = 0.05 lots. With a 50-pip stop it would be 0.02 lots.

Does leverage increase my risk?

It lets you open bigger positions with less capital, and that is where the danger lies. If you size trades with the risk formula, leverage only determines the margin set aside; if you don't, it multiplies your losses.

How much is one pip worth on a lot of EUR/USD?

$10 per pip on a standard lot, $1 on a mini lot (0.10) and $0.10 on a micro lot (0.01). If your account is in euros, divide by the EUR/USD rate.

Should I calculate risk on my current balance or my starting capital?

On your current balance. That way your size shrinks automatically during losing runs and grows as the account grows, which is what protects your capital.

Does the same formula work for crypto and indices?

Yes. What changes is the value of each unit of movement: per index point or per dollar of the crypto price, depending on your broker's contract. The logic (risk ÷ stop distance × value per unit) is the same.