TOOLS · CALCULATOR
Forex Position Size Calculator
Updated 2026-09-04 · Educational content · No broker owns this site
Quick answer. Position size in forex equals your risk amount divided by the stop-loss distance in pips multiplied by the pip value per lot. Risking $100 with a 20-pip stop on EUR/USD, where one pip is worth $10 per standard lot, gives 0.50 lots.
Position size calculator
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Not sure what pip value to enter?
- The quote currency is your account currency (EUR/USD, GBP/USD, AUD/USD on a USD account): pip value is exactly 10.00 per standard lot. A pip is 0.0001 and 0.0001 × 100,000 = 10.
- A JPY pair (USD/JPY, EUR/JPY): a pip is 0.01, so a standard lot moves 1,000 JPY per pip. Convert that into your account currency below.
- Anything else (EUR/GBP on a USD account, for example): your broker's contract specification or its own pip-value tool gives the figure. Enter it here.
This calculator does the arithmetic on the numbers you type. It does not know your broker's live prices, spread, swap or commission, and it is not advice on whether to take a trade.
How is forex position size calculated?
Position size is not a preference — it is the output of a division. You decide what a loss is allowed to cost you, you decide where the stop belongs, and the lot size is whatever makes those two agree:
Position size (lots) = Risk amount ÷ (Stop distance in pips × Pip value per lot)
Each variable, in plain terms:
- Risk amount — the money you accept to lose if the stop is hit. Either a percentage of the balance (balance × risk %) or a fixed cash figure you set once and reuse.
- Stop distance in pips — the gap between your entry and your stop, measured in pips. This comes from the chart, not from the size you would like to trade.
- Pip value per lot — what one pip is worth on one standard lot, in your account currency. For a pair quoted in your own currency it is exactly 10.00, because 0.0001 × 100,000 units = 10.
The order matters more than the formula. The stop goes where the trade idea stops being valid; the size then adapts to it. Do it the other way round — pick the lot size first, then hunt for a stop that "fits" — and the stop is no longer a risk limit, just a number that happens to be on the screen.
How do you use this calculator?
- Enter your account balance and pick the currency your account is denominated in.
- Choose how you define risk. A percentage keeps the risk shrinking automatically when the account shrinks; a fixed amount does not. Most beginner guidance sits between 0.5% and 1%.
- Measure the stop distance in pips from your chart — entry price to stop price — and type it in. Do this before you think about lot size.
- Set the pip value per standard lot. Leave it at 10.00 for EUR/USD, GBP/USD or AUD/USD on a USD account; use the helper for JPY pairs and crosses.
- Press calculate. You get the exact size, the size your platform will actually accept, and what that rounded size really risks.
What does a worked example look like, step by step?
A $10,000 account, risking 1% per trade, on a EUR/USD idea whose stop sits 20 pips away.
| Step | Working | Result |
|---|---|---|
| 1. Risk amount | $10,000 × 1% | $100 |
| 2. Cost of the stop on one standard lot | 20 pips × $10 per pip | $200 |
| 3. Position size | $100 ÷ $200 | 0.50 lots |
| 4. In units | 0.50 × 100,000 | 50,000 units |
Half a standard lot, or five mini lots. If EUR/USD falls 20 pips to your stop, the loss is 50,000 × 0.0001 = $100 — exactly the 1% you decided on before you opened the chart. Widen the stop to 40 pips and the same $100 buys you only 0.25 lots. Nothing about the risk changed; only the size did.
Why is your real position size never quite what the formula says?
The formula returns numbers like 0.406 lots. No broker will accept that. Platforms trade in steps — usually 0.01 lots, sometimes 0.10 — so the honest answer is the size you can actually place and the risk that size really carries.
Take the classic textbook case: a $10,000 account, 2% risk, a 50-pip stop on USD/JPY where a pip is worth $9.85 per standard lot. The formula gives ($10,000 × 2%) ÷ (50 × 9.85) = $200 ÷ $492.50 = 0.406 lots. Rounded down to a tradeable 0.40 lots, the real risk is 0.40 × 50 × $9.85 = $197.00, not $200. That is the number this calculator shows you, because rounding down is the version that never quietly increases your risk.
Two more things the arithmetic does not include: the spread and any commission are a cost on top of the stop, and a gap through your stop level can fill you worse than the price you planned. Both push the real loss slightly above the calculated one — another reason to round down rather than up.
What do beginners get wrong about position sizing?
- Choosing the lot size first. Then the stop gets placed wherever that size makes the loss feel tolerable, which is usually far too close to the entry. Size follows the stop, never the reverse.
- Treating a tight stop as permission to trade bigger. A stop that tight often belongs to a timeframe you cannot supervise. A smaller size, not a larger one, is the usual answer.
- Raising the risk percentage after a winning run. Recent wins do not change the edge; they only change how large the eventual losing streak will be in cash terms.
- Mixing a fixed cash risk with a shrinking account. A flat $200 is 2% of $10,000 but 4% of $5,000 — the risk creeps up exactly when the account can least absorb it.
- Recalculating nothing when the pair changes. Pip value is not 10.00 on every pair, and a wrong pip value quietly scales the whole position.
- Sizing several correlated trades independently. Three long positions in EUR/USD, GBP/USD and AUD/USD at 1% each are closer to one 3% bet on a falling dollar than to three separate 1% risks.
The deeper version of this — why a small, fixed unit is what lets a losing streak stay survivable — is covered in the lesson on risk per trade. If you want the size decision written down before you are in front of a live chart, the trading plan template and the pre-trade checklist both have a line for it.
Frequently asked questions
What position size should I use on a small account?
The same arithmetic applies at any balance, but the smallest tradeable size sets a floor. On a $200 account risking 1% ($2) with a 20-pip stop on EUR/USD, the formula gives 0.01 lots, and 0.01 lots actually risks $2.00 — it fits exactly. Shorten the balance or widen the stop and the required size falls below 0.01 lots, at which point no tradeable position keeps you inside your risk limit. The calculator tells you when that happens instead of rounding up.
Is 1% or 2% risk per trade better?
Neither is a rule, and the honest answer is arithmetic rather than advice. Ten consecutive losses take about 9.6% off an account at 1% risk and about 18.3% at 2%, because each loss is taken from a smaller remaining balance. What that means for you depends on how many losses your method produces in a row and how you behave after them. Most beginner guidance sits at 0.5–1%; the deeper reasoning is in our lesson on risk per trade.
Do I need to add the spread and commission?
The formula does not include them. The spread widens your effective loss because you enter at the ask and exit at the bid, and commission is charged on top. Both make the real loss slightly larger than the calculated one. This calculator rounds the position size down rather than up, which leaves a small buffer, but if your costs are meaningful — a wide spread on an exotic pair, for example — add them to the stop distance in pips before you calculate.
Why does my broker reject the lot size the formula gives?
Because platforms trade in fixed increments, usually 0.01 lots and sometimes 0.10. A formula answer of 0.406 lots is not placeable. The calculator shows both figures: the exact answer and the nearest size below it that your platform will accept, together with what that rounded size really risks. Rounding down keeps you inside your limit; rounding up quietly breaks it.
Can I use this for gold, indices or crypto CFDs?
The structure works for any instrument, but the pip value field has to change. Gold, indices and crypto CFDs are usually quoted in points or ticks rather than pips, and the value per point per contract is set by your broker's contract specification. Put the stop distance in points into the pips field and the value per point per contract into the pip value field, and the division is the same.
Sources
- FXStreet Learning Center, Unit C ch.3 — The Position Size (formula and worked example: $10,000, 2%, 50 pips, $9.85 pip value = 0.40 lots)
- BabyPips — Position Size Calculator (same inputs: account size, risk %, stop in pips, pip value)
- FirstPip knowledge base — risk/risk-per-trade (S001, S002): position size is derived from the risk amount, not chosen first