How to use this position size & risk calculator
- Enter cash available for this scenario, rather than borrowed buying power.
- Choose hypothetical entry, stop and target prices in the same currency.
- Enter per-side percentage fees and the tradable unit increment.
- Compare rounded units, required cash and modeled outcomes; verify actual broker rules.
Keep the original input record beside the calculator. All fields have named units, and blank or invalid values produce a check message rather than a useful result. Reset restores the illustrative scenario; it does not choose inputs for your project. Numbers are calculated locally in the current page, without an account or a remote calculation service.
Formula and worked example
With $10,000 cash, a 1% budget, $50 entry, $48 stop, $56 target and 0.1% fees on each side, the model allows 47 whole units. Entry cash is $2,352.35 including its fee. The stop scenario loses $98.61 and the target scenario gains $277.02 after modeled fees. Neither outcome is a forecast.
The displayed decimals are a presentation choice. Keep the underlying input measurements at the precision you can justify, and avoid treating a rounded output as proof that the inputs were measured with the same accuracy.
Interpretation checks
A budget is an input, not a recommendation
The risk percentage expresses the scenario you want to examine. The calculator does not choose an appropriate percentage for you or assess whether you can afford a loss. Keep the cash balance, chosen percentage and currency together in your notes. A correct unit count cannot establish that a trade is suitable.
Keep price distance and fees separate
A two-dollar difference between entry and stop is only the price component of the loss model. Percentage charges at entry and exit add another cost. This tool uses the same percentage on both sides and excludes fixed commissions, spread, slippage and taxes. Use a different model when those charges are material.
Rounding changes exposure
A market may allow only whole shares or another minimum quantity. Rounding down can leave part of the risk budget unused. The available-cash cap can reduce the position again. Neither difference is an error: the displayed quantity respects the increment and the cash inputs rather than assuming fractional units are always available.
Execution remains uncertain
A stop scenario assumes an exit at the price entered. Gaps, liquidity and order handling can produce a different fill. Stop-limit orders introduce another tradeoff because a limit may prevent execution. Read the actual order documentation instead of treating the modeled loss as a maximum guaranteed loss.
Keep a comparison record
Start with the question you want the position size & risk calculator to answer. Save the inputs, named units, source of each value and the output together. Preserve the original before changing an assumption. This makes a second scenario comparable and helps identify whether a different result came from the model, a measurement or a changed source value.
For this topic, the most useful boundary is: keep price distance and fees separate. A two-dollar difference between entry and stop is only the price component of the loss model. If the calculator cannot represent the condition you need, keep a separate worksheet rather than changing unrelated fields until the result looks plausible. The practical journal guide develops that record in more detail.
Questions and limits
Does the tool place an order?
No. It performs arithmetic in your browser and has no broker connection. It does not receive market prices, place orders or monitor a position.
Why is the unit count lower after adding fees?
Fees increase the modeled loss per unit and the cash needed to enter. Rounding and the available-cash cap can reduce the final unit count further.
Can I use it for options or leveraged forex?
No. Contract multipliers, margin, currency conversion and product-specific risks are outside this cash-funded long-only model.
Model limit: Educational arithmetic only. No trading signals, leverage, derivatives, short positions, tax calculation or investment recommendation. A stop is not a guarantee of an execution price.
References and corrections
References are provided for context, not as endorsements. The tool does not import measurements, prices, rates or requirements from them. Check the exact source relevant to your own input before making a decision. The editorial policy explains our approach, and the contact page accepts reproducible calculation issues without private records.