Forex Position Size & Lot Size Calculator
Calculate forex position size from an entered balance, loss-budget percentage and stop. Use either a pip distance or entry and stop prices, inspect the mathematical lot size, then apply broker minimum, maximum and volume-step rules by rounding down. The output is deterministic planning arithmetic, not a recommended risk level or order.
Trade inputs
Use the same balance, stop definition and contract context you intend to evaluate.
Balance used to convert the selected percentage into a monetary loss budget.
Currency in which the account balance and calculated risk amount are displayed.
Absolute pip distance from the intended entry to the stop; it is not a price.
The stop distance is the absolute entry-to-stop difference divided by the entered pip size.
May be above or below entry; only the absolute distance is used.
Loads editable reference values for pip size and standard contract quantity.
Reference: 0.0001 for most FX pairs, 0.01 for JPY pairs and this site's XAU/USD convention.
Units represented by one standard lot. Replace the reference with the broker symbol specification.
Smallest lot amount accepted for the broker symbol.
Allowed increment from the broker's minimum volume.
Largest lot amount accepted for the broker symbol. This is an entered execution constraint, not a suitability threshold.
Enter the displayed conversion pair in the direction described here.
Derived from the selected instrument metadata and, when required, your manual conversion rate.
Calculated position
Calculated equivalents with the display precision stated below.
Lot-size methodology and formula
The calculator first turns the entered account percentage into a monetary loss budget. It derives stop pips directly or from the absolute entry-to-stop price distance, then divides the budget by the monetary stop value for one standard lot. A separate model rounds the result down to an entered broker step.
Stop pips from prices = |Entry - Stop| / Pip size
Mathematical standard lots = Risk amount / (Stop pips x Pip value per standard lot)
Broker-step lots = Minimum + floor((Capped lots - Minimum) / Step) x Step
Worked example: loss budget to lot size
How to interpret the result
The 0.20-lot result only aligns the entered stop distance with the selected USD 100 loss budget before gaps, slippage, commissions and broker rounding. It does not establish that 1% is suitable, that the stop is technically valid or that the order will be accepted.
What a fixed percentage loss budget does mathematically
The illustration below starts at USD 10,000 and applies the same percentage loss to the reduced balance after every loss. It does not recommend any percentage or predict a losing streak.
Scroll horizontally to compare every illustrative loss sequence.| Entered loss budget | After 5 losses | After 10 losses | Gain needed to recover |
|---|---|---|---|
| 1% | USD 9,510 | USD 9,044 | 10.6% |
| 2% | USD 9,039 | USD 8,171 | 22.4% |
| 5% | USD 7,738 | USD 5,987 | 67.0% |
| 10% | USD 5,905 | USD 3,487 | 186.8% |
Lots and units
For conventional spot-FX contracts, one standard lot is commonly 100,000 base-currency units. Mini and micro lots are unit equivalents; the broker's instrument specification controls what can actually be ordered.
Scroll horizontally to compare lot labels and unit equivalents.| Label | Standard-lot equivalent | Common FX base units |
|---|---|---|
| Standard lot | 1.00 | 100,000 |
| Mini lot | 0.10 | 10,000 |
| Micro lot | 0.01 | 1,000 |
In this calculator, “lot size” is the volume expressed in lots, while “position size” can also be expressed as base units. The displayed base units equal the broker-step lot amount multiplied by the editable contract size.
Assumptions and limits
- Exchange-rate fields are manual and have no automatic timestamp.
- Pip size and contract size are loaded from reference metadata but remain editable because CFDs, metals and broker-specific symbols can differ.
- The entered minimum, maximum and volume step are applied arithmetically; the page cannot confirm that a broker will accept an order.
- The result does not check available margin, leverage, spread, commission, slippage or stop execution.
- The broker-step result is rounded down so it does not exceed the selected loss budget under the entered assumptions.
Sources and methodology
- MQL5 Reference — symbol properties documents contract size, minimum volume and volume-step fields that must be checked against the broker symbol.
- CFTC customer advisory — eight things to know before trading forex provides leverage and retail-forex loss-risk context; it does not prescribe a position size.
Frequently asked questions
- Lot size expresses trade volume in standardized units. For conventional spot FX, one standard lot is commonly 100,000 base-currency units, one mini lot is 10,000 and one micro lot is 1,000. Broker contract specifications can differ.
- Standard lots = (account balance x selected risk percentage) / (stop distance in pips x pip value per standard lot). For USD 10,000, 1%, 50 pips and USD 10 per pip, the result is 0.20 standard lots.
- No. It is the mathematical result of the values you enter. It does not assess whether a trade, stop placement or account-risk percentage is suitable for you.
- It is an illustration in which the selected loss budget equals 1% of the entered balance. It is not a universal rule or a claim that 1% is appropriate for every trader.
- Lot size expresses volume in lots, while position size may be stated in lots or base-currency units. Here, base units equal the broker-step standard-lot amount multiplied by the editable contract size.
- At the same balance, selected percentage and pip value, lot size is inversely proportional to stop distance. Doubling the entered stop distance halves the calculated lots.
- Pip value depends on pip size, contract size, quote currency, account currency and any required conversion rate. For EUR/USD in a USD account, a conventional standard lot is USD 10 per pip; other instruments and account currencies can differ.
- Required margin also depends on current price, leverage, currency conversion and broker account terms. Use the dedicated Margin Calculator with those inputs instead of inferring margin from lot size alone.
- Many brokers accept fractional lots, but minimum, maximum and step values vary by broker, account and instrument. Enter the verified symbol rules here; the calculator rounds down and returns zero rather than rounding up from a mathematical size below the entered minimum.
Continue your pre-trade checks
Compare broker contract terms
Before using a calculated volume, verify the symbol specification and account terms for the broker entity available in your jurisdiction.
FBS
Check the instrument specification and account conditions that apply to your entity.
Check FBS termsFXOpen
Confirm available volume increments, contract size and margin terms before ordering.
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