Quick answer
Position size is calculated as (Account Balance × Risk %) ÷ (Stop Loss in pips × Pip Value), so every trade risks the same fixed percentage of your account regardless of how far away the stop loss is. Risk-reward ratio is calculated as (Take Profit − Entry) ÷ (Entry − Stop Loss), and both numbers should be checked before entering, not after — entering first and sizing later reverses the risk management.
Two numbers decide whether a trade is sized and planned responsibly before you ever click buy or sell: how much of the account you're risking, and what you stand to gain relative to what you're risking. Both have to be calculated before entry — figuring either out after the fact defeats the purpose.
Position sizing: risking a fixed percentage, not a fixed lot size
The mistake many new traders make is trading the same lot size on every setup, regardless of how far the stop loss sits. That means a tight-stop trade risks far less of the account than a wide-stop trade at the identical lot size — an inconsistency that makes it impossible to compare strategies fairly. Fixed-percentage position sizing fixes this: it solves for whatever lot size risks the exact same dollar amount (a fixed % of the account) no matter how wide the stop is.
Formula used:
Position Size (units) = (Account Balance × Risk %) ÷ (Stop Loss in Pips × Pip Value per Unit)
Why fixed lot size vs fixed risk % produce very different outcomes
| Stop loss distance | Fixed 1 standard lot (wrong) | Fixed 1% account risk (right) |
|---|---|---|
| 10 pips | Risks a small, inconsistent % of account | Larger position size, same 1% risked |
| 50 pips | Risks 5× more than the 10-pip example, same lot size | Smaller position size, still exactly 1% risked |
Risk-reward ratio: what you stand to gain, relative to what you're risking
Risk-reward ratio compares the distance from entry to your take profit against the distance from entry to your stop loss. A 1:3 ratio means you stand to gain three times what you're risking if the trade hits target — which is why a lower win rate can still be profitable at a high enough ratio.
Formula used:
Risk-Reward Ratio = (Take Profit − Entry Price) ÷ (Entry Price − Stop Loss)
Why you check both together, before entry
- Set your stop loss and take profit based on the chart first — structure, not an arbitrary pip count
- Calculate the risk-reward ratio from those levels — if it's too low for your strategy's typical win rate, the trade isn't worth taking regardless of position size
- Only then calculate position size, using your fixed risk % and the stop-loss distance you already set
- Run both numbers at once with the Position & Lot Size Calculator and the Risk-Reward Calculator in the same Trading Calculator Suite
Once a setup checks out on both numbers, log it straight to the Trading & Asset Journal via the Trading Calculator Suite's "Log to Journal" button, so the exact risk-reward ratio you planned with is the one that ends up in your journal.
For educational and informational purposes only — not financial, investment, trading, legal or tax advice. See our full Financial Disclaimer.