Free Position Size Calculator: Exact Lot Size for Any Trade (Forex & Gold)

Position sizing is the single decision that separates traders who survive from those who don't. Enter your account size, the risk you're willing to take, and your stop loss — the calculator returns the exact lot size for the trade.

.fxsc{font-family:inherit;max-width:560px;margin:20px 0;padding:20px;border:1px solid #ddd;border-radius:10px;background:#fafafa} .fxsc label{display:block;font-weight:600;margin:12px 0 4px} .fxsc select,.fxsc input{width:100%;padding:8px;border:1px solid #ccc;border-radius:6px;font-size:15px;box-sizing:border-box} .fxsc .fxsc-out{margin-top:16px;padding:14px;background:#1e5f2e;color:#fff;border-radius:8px;text-align:center} .fxsc .fxsc-big{font-size:26px;font-weight:700} .fxsc .fxsc-note{font-size:12px;color:#888;margin-top:10px}(function(){ var R={EURUSD:{pv:10,c:'USD'},GBPUSD:{pv:10,c:'USD'},AUDUSD:{pv:10,c:'USD'},NZDUSD:{pv:10,c:'USD'},USDJPY:{pv:1000,c:'JPY'},USDCHF:{pv:10,c:'CHF'},USDCAD:{pv:10,c:'CAD'},EURGBP:{pv:10,c:'GBP'},XAUUSD:{pv:1,c:'USD'}}; var toUSD={USD:1,JPY:1/150,CHF:1/0.88,CAD:1/1.36,GBP:1.27,EUR:1.08}; function calc(){ var bal=parseFloat(document.getElementById('fxsc-bal').value)||0, a=document.getElementById('fxsc-ccy').value, risk=parseFloat(document.getElementById('fxsc-risk').value)||0, sl=parseFloat(document.getElementById('fxsc-sl').value)||0, p=document.getElementById('fxsc-pair').value; var sym=a==='EUR'?'\u20ac':'$'; var d=R[p],pipUSD=d.pv*toUSD[d.c],pipAcct=a==='EUR'?pipUSD/1.08:pipUSD; var riskAmt=bal*risk/100; var lots=sl>0&&pipAcct>0?riskAmt/(sl*pipAcct):0; document.getElementById('fxsc-res').textContent=lots.toFixed(2)+' lots'; document.getElementById('fxsc-det').textContent='Risking '+sym+riskAmt.toFixed(2)+' ('+risk+'%) | pip value '+sym+pipAcct.toFixed(2)+'/lot | '+Math.round(lots*100)+' micro lots'; } ['fxsc-bal','fxsc-risk','fxsc-sl'].forEach(function(id){document.getElementById(id).oninput=calc;}); ['fxsc-ccy','fxsc-pair'].forEach(function(id){document.getElementById(id).onchange=calc;}); calc(); })();

The formula behind it

Position size = (account balance × risk %) ÷ (stop loss in pips × pip value per lot)

Example: $1,000 account, 1% risk ($10), 25-pip stop on EUR/USD where one pip is worth $10 per lot. Position size = $10 ÷ (25 × $10) = 0.04 lots. That's it — everything else is refinement.

The mistakes this calculator prevents

• Fixed-lot trading. Trading 0.10 lots "because it feels right" means your risk changes with every stop distance. A 20-pip stop and a 100-pip stop are completely different trades.
• Ignoring the pair. One pip on EUR/USD is worth $10 per lot; on USD/JPY it's roughly $6.70 at recent rates. Same lots, different risk.
• Gold amnesia. XAU/USD pip conventions differ from forex pairs, and gold's daily range is 3-5x wider. Sizing gold like EUR/USD is the classic way new EA accounts die — see why gold trading differs from forex.

How much should you risk per trade?

The professional consensus for retail accounts is 0.5-2%. Above 2%, a normal losing streak of 8-10 trades — which every strategy eventually has — destroys 20%+ of the account and triggers the emotional spiral that finishes the job. If you trade with an Expert Advisor, this rule applies to the portfolio, not just each trade: three correlated gold EAs risking 1% each are really one 3% bet. Our long-term risk management guide goes deeper, and the lot size tutorial shows how to set this up inside MT4/MT5.

FAQ

Does this work for gold (XAU/USD)? Yes — select Gold from the instrument list. The calculator uses the standard convention of 1 lot = 100 oz and a $0.01 pip. Check your broker's contract specification to confirm.

What if my stop loss is tight, like 5 pips? The math still works, but beware: with tight stops the spread and slippage become a huge share of your risk. On a 5-pip stop, a 1-pip spread is 20% of your planned risk before the trade even starts.

Should I round the result? Round down, never up. If the calculator says 0.047 lots, trade 0.04. Rounding up systematically over-risks every trade.

My EA computes its own lot size — do I still need this? Yes. Use it to audit your EA: run the same inputs through the calculator and compare. If the EA's lot differs significantly, find out why before going live. Our MT5 backtesting guide shows how to verify EA behavior safely.

Trading forex and gold on margin carries a high level of risk. This tool is educational and does not constitute investment advice.