Forex lot size calculator

The lot size formula (works for every instrument)

Position size in lots = (Account × Risk %) / (Stop-loss in pips × Pip value per 1 lot). Example: a $10,000 account, 1% risk, 20-pip stop on EURUSD ($10 per pip per lot) → ($10,000 × 0.01) / (20 × $10) = 0.5 lots. If the stop is hit, you lose exactly $100 — never more.

The formula has three moving parts and each of them breaks in a predictable way. Risk % drifts up after a winning streak ('I'm hot today'). Stop distance shrinks because a tighter stop allows a bigger lot. Pip value gets ignored on JPY pairs and gold, where it differs from majors. A calculator removes all three failure modes because the number is the number.

On prop firm accounts the formula needs one more constraint: your per-trade risk must leave room inside the Daily Loss limit. At FTMO (5% daily loss), risking 1% per trade means five full stops in a day end the challenge. Most funded traders run 0.25–0.5% per trade for exactly this reason.

Want the number right now? Use the interactive position size calculator — forex, gold, indices and crypto, no sign-up.

Worked examples: 0.5% and 1% risk

Same account, same stop, two risk levels — this is how much the lot size changes:

• $10,000 account, 1% risk, 20-pip stop (EURUSD). Risk $100 → 0.50 lots. Ten losses in a row = -10% of the account. Survivable, recoverable.
• $10,000 account, 0.5% risk, 20-pip stop (EURUSD). Risk $50 → 0.25 lots. Ten losses in a row = -5%. This is the setting most FTMO traders use.
• $10,000 account, 1% risk, 50-pip stop (swing). Risk $100 → 0.20 lots. A wider stop means a smaller position for the same dollar risk.
• $100,000 FTMO account, 0.5% risk, 15-pip stop. Risk $500 → 3.33 lots. Daily Loss at 5% ($5,000) tolerates ten consecutive full stops.

Why 'just this once bigger' destroys accounts

Position sizing errors don't hurt on the trade you take — they hurt in the distribution. If 1 in 20 of your trades is 3× the planned size, that single trade carries the weight of 60 normal trades. One bad fill on it erases a month of discipline.

This is exactly what a trading journal catches: in TradeLogic you see your lot-size distribution per instrument and per session, so 'just this once' shows up as a bar on a chart. Combined with the prop firm tracker, you get an alert when a single position can breach Daily Loss — before you open it, not after.

TradeLogic vs Excel, TradeZella and TraderSync

You can compute lot size in a spreadsheet — until you're mid-session with 40 seconds before the candle closes. Here's how the options compare.

How it works in TradeLogic — 3 steps

1. 1

   Set your risk % once

   0.25–0.5% for prop firm challenges, 0.5–1% for personal accounts. Write it down and don't renegotiate it mid-session.

2. 2

   Measure the stop first

   The stop-loss comes from the chart, not from the lot size you want. Structure first, then size.

3. 3

   Compute lots, then round down

   Formula: (Account × Risk%) / (SL pips × pip value). Rounding down keeps you inside risk when spread and slippage hit.

How much you save

The calculator on this page is free forever. If you want sizing checked automatically against your prop firm rules before every trade, that's the Prop Firm Tracker in TradeLogic PRO ($4.99/mo billed yearly).

FAQ — frequently asked questions

See also

• Position size calculator

  The interactive version — three fields, instant lot size.

• Risk / reward calculator

  Check R:R before you click BUY.

• Prop firm calculator

  Daily Loss and Max DD in dollars for your challenge size.

• Trading journal

  See your real lot-size distribution from imported trades.

• Position size calculator

  Lot size at 0.5% and 1% risk — no sign-up needed.

• TradeLogic — homepage

  The full trading journal: auto-import, AI analytics, prop firms.