Orders & execution · Intermediate

Position Sizing Basics

Position size is an output, not a choice. Your account, your risk limit and your stop distance decide it, and the arithmetic takes ten seconds.

Last reviewed 15 September 2026 by the MarketPro research desk · Editorial policy

In short

Position size equals your risk amount divided by the stop distance in pips multiplied by the pip value per lot. On a $10,000 account risking 1%, that is $100 against a 25-pip EUR/USD stop where a standard lot is $10 a pip: $100 divided by $250 gives 0.4 lots. Widen the stop to 50 pips and the same $100 of risk buys 0.2 lots.

What to remember

A wide stop is not riskier than a narrow one, it is a smaller position. Twenty-five, fifty and a hundred pips all risk $100 at 0.40, 0.20 and 0.10 lots.
Pip value is not always $10 a lot. A GBP/JPY pip is about $6.67 with USD/JPY at 150 and a EUR/GBP pip about $12.70, so a blanket $10 mis-sizes you in both directions.
Three correlated 1% trades are one 2.5% to 3% trade. A per-trade limit needs a total-open-risk limit above it.
The 1% is a planned loss, not a maximum. A gap fills the stop wherever the market reopens, which can be several times further.

Lesson 12 of 16 in Orders and execution

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$10,000, 1% risk, a 25-pip stop: 0.4 lots

Position sizing is the decision about how much capital to commit to one trade. It is worked out from your account, your risk limit and your stop distance, and it is arithmetic rather than judgement. Most people make it the other way round, which is why it is the decision that decides more accounts than entry selection ever does.

Here is the whole thing on one trade. A $10,000 account, a rule of 1% risk per trade, so $100 at stake. A long EUR/USD taken from 1.0800, stop at 1.0775, so 25 pips of room. A standard lot of EUR/USD is worth about $10 a pip, so one lot would lose $250 if the stop were hit. You want to lose $100, and $100 divided by $250 is 0.4. The position is 0.4 lots.

Check it in the other direction: 0.4 lots is $4 a pip, and 25 pips of loss is $100. That is the number you decided on before you looked at the chart. The position size calculator does this in a second, and doing it by hand once is worth it because then you know what the tool is doing.

The formula, and the three numbers it needs

Written out: size = risk amount / (stop distance in pips x pip value per lot).

Risk amount comes from your account balance and your per-trade percentage. Decided once, in advance, applied to every trade.
Stop distance comes from the chart. Where the trade idea is wrong, not where you would like it to be.
Pip value comes from the instrument, and it is the one people get wrong.

The order matters. Risk and stop are inputs; size is an output. Deciding you want two lots and then placing a stop where two lots gives an acceptable loss is the same calculation run backwards, and it produces a stop that has nothing to do with the market.

One risk budget, three stop distances, three sizes

Keep the $100 fixed and change only the stop.

Instrument	Stop	Loss per standard lot	Position size
EUR/USD	25 pips	$250	0.40 lots
EUR/USD	50 pips	$500	0.20 lots
EUR/USD	100 pips	$1,000	0.10 lots

Three completely different positions, all risking exactly $100. This is the point that makes the whole discipline work: a wide stop is not more dangerous than a narrow one, it is simply a smaller position. The danger comes from holding size constant and letting the stop distance set the loss, which is what happens when someone always trades one lot.

It also means a volatile instrument is not off limits, it just sizes smaller. Gold moves in dollars rather than pips, and a standard XAU/USD lot is 100 ounces, so a $1 move is $100. An $8 stop risks $800 a lot, and the same $100 budget buys 0.125 lots.

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Pip value is where the formula quietly breaks

Ten dollars a pip is true for a standard lot of any pair quoted against the US dollar, and not otherwise. On GBP/JPY a standard lot pip is 1,000 yen, which with USD/JPY at 150 is about $6.67. Feed $10 into the formula there and the denominator is too big, so you take a position a third smaller than you meant to and risk $67 where you intended $100. The error runs the dangerous way round on a pair quoted in something worth more than the dollar. A EUR/GBP pip is 10 pounds, about $12.70 with sterling at 1.27, so the same blanket $10 over-sizes you by more than a quarter and the loss turns up bigger than planned. The pip calculator handles the conversion in both directions.

Two more places the output needs a sanity check.

Margin. The formula tells you what to risk, not what you can fund. Those 0.4 lots are $43,200 of notional exposure, which at 1:30 leverage requires about $1,440 of margin, or 14% of the account tied up in one position. Check it with the margin calculator before assuming the trade is placeable.
Gaps. The 1% is what you lose if the stop fills where you put it. Across a weekend gap or a central bank surprise it can fill far worse, so the honest description is a planned loss rather than a maximum.

Correlation turns three 1% trades into one 3% trade

Sizing each trade correctly and then opening six of them is a common way to be disciplined and over-exposed at the same time. Long EUR/USD, long GBP/USD and long AUD/USD at 1% each are not three independent 1% risks. They are one short-dollar position of roughly 2.5% to 3%, because on a dollar rally all three lose together.

The fix is a second limit that sits above the per-trade one: a cap on total open risk, and a cap on risk in any one theme. Something like 1% per trade, 3% open at any time, and no more than 2% pointing the same way on the same driver. The numbers are yours to set. Having the second limit at all is the part that matters, and our risk management guide covers where the rest of the limits go.

Deciding the size before you look at the entry

There is no universally correct position size. It depends on your capital, your tolerance and the method. What separates a workable approach from an unworkable one is whether the figure was decided in advance or produced by how a particular setup made you feel.

A routine that holds up under pressure:

Write the per-trade percentage into your plan once and recalculate the cash figure weekly, not per trade, so a losing run scales you down automatically.
Place the stop from the chart, then compute the size. Never the reverse.
Round down. 0.37 lots becomes 0.35, not 0.40.
If the resulting size feels too small to be worth taking, the account is too small for that stop distance, and the answer is a different timeframe rather than a bigger position.

The conviction you feel about a trade is not information about its outcome, and sizing up on it is how a normal losing run becomes a serious one.

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Written and reviewed by the MarketPro research desk

MarketPro is a trading-signal and trading-education app operated by Harajuku Holdings LTD (Cyprus). Our signal desk publishes and tracks every trade idea in-app, and every page here is checked against the app's live behaviour before publishing. Last reviewed 15 September 2026. How we produce signals and content · About MarketPro

FAQ

Position Sizing Basics: questions

How do you calculate position size in forex?

Divide the cash you are willing to lose by the stop distance in pips multiplied by the pip value of one lot. A $10,000 account risking 1% has $100 at stake; a 25-pip stop on EUR/USD costs $250 per standard lot, so $100 divided by $250 gives a 0.4 lot position. Confirm it in reverse: 0.4 lots is $4 a pip, and 25 pips is $100.

What percentage of an account should you risk per trade?

There is no correct figure, but the arithmetic constrains the sensible range. At 1% a run of ten losses costs about 9.6% of the account; at 10% the same run costs 65% and needs a 187% gain to recover. Most written plans land between 0.5% and 2%, with smaller figures for newer traders and for methods with lower win rates or longer losing streaks.

Should position size change after a losing streak?

It does automatically if you calculate the risk amount from the current balance rather than the starting one, which is the main argument for percentage-based sizing. Some plans also add a step-down rule, halving size after a defined drawdown and restoring it after a set number of trades back above a threshold. What matters is that the rule is written in advance rather than applied when you feel shaken.

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