Free trading calculators: lot size, risk, swaps, R and drawdown

Six free calculators for the sums every swing trader does: lot size, risk per trade, swap fees, R-multiple and expectancy, prop-firm drawdown and losing-streak odds. Each one runs in your browser with no sign-in, shows the formula and a worked example, and uses the same engines as the calculators inside the Trade Desk.

By RB Trading · Updated 20 Oct 2026 · Educational analysis, not financial advice

The calculators

Position size calculatorHow do I calculate lot size? Lots, shares or units from your risk and your stop, with live pip values on the crosses.Risk per trade calculatorHow much should I risk per trade? What a percentage risks in cash, and what a losing run would cost at it.Swap fee calculatorHow do I calculate swap fees on a trade? Long and short overnight cost from central bank rates, triple Wednesday included.R-multiple and expectancy calculatorHow do I calculate R-multiple and expectancy? One trade’s R from its levels, and a set of trades’ expectancy.Prop firm drawdown calculatorHow much can I still lose on a prop firm account? Daily and maximum loss floors, static or trailing, and the trades they leave.Losing streak odds calculatorWhat are the odds of a losing streak? The exact chance of a run of losses, from your win rate and trade count.

The numbers behind them

Swap fees by assetWho pays and who earns overnight on 24 forex pairs, metals, oil, indices and bitcoin, updated from central bank rates.Swing trading statisticsWin rate, losing streaks, drawdown and target hit rate, answered from a published record with every loser left in.Swing trading guidesThe method behind the sums: stops, sizing, streaks and prop-firm rules.

Why these, and not a dozen more

These are the sums that decide whether an account survives: how big each trade is, what it costs to hold, what it returned in units of risk, how much room a prop firm leaves, and how long a bad run can last. Get them right and a method has the time it needs to work. Each page answers its question in a sentence first, then lets you run your own numbers.

Inside the Trade Desk the same maths runs on every weekly call: a member saves their account once and each setup shows its size in lots or shares, its swap and its live R.

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FAQ

Are these trading calculators free?

Yes. They run in your browser with no sign-in and nothing to install.

Do the calculators use live prices?

The position size calculator takes live forex rates for pip values on cross pairs, and the swap calculator uses central bank rates that update after each decision, with reference prices for metals, oil, indices and crypto.

Is this financial advice?

No. The calculators do arithmetic on the numbers you enter. Decisions about what to trade and how much to risk are yours.

Keep readingSwap fees by asset · Swing trading statistics · All guides · The published record