1% EA risk: fixed reference or current balance?

Separate comparison from compounding

A fixed reference keeps the nominal sizing budget comparable across trades. Current-balance sizing changes the budget after realized gains or losses. Neither choice is universally suitable. When comparing backtests, declare the mode, initial balance, reference and account currency; changing only the label from EUR to USD does not convert the values.

Translate budget into executable volume

Calculate the expected loss at the intended initial stop using actual broker symbol specifications. If EUR 100 buys 0.333 raw lots and the step is 0.01, rounding down gives 0.33 lots. If the minimum lot exceeds the budget, skip the illustrated entry. A fixed lot amount by itself does not define fixed monetary risk.

Add concurrent positions

Three EAs each planning one EUR 100 initial stop create EUR 300 of simultaneous planned exposure. On a EUR 10,000 balance that is 3%, before additional costs. This is arithmetic, not a guaranteed worst-case loss: gaps, execution, margin and account interactions need their own checks. Use the calculator to explore your own assumptions before copying risk inputs into MT5.

Checks to make before deciding

• Fixed reference: budget = risk% x reference capital. At 1% of EUR 10,000 the initial sizing budget is EUR 100 per trade even after gains or losses.
• Current balance: budget = risk% x balance at sizing time. Record that timestamp and how open positions, cash movements and new orders affect the basis used by the EA.
• Fixed lots: record volume and the resulting stop risk for each trade. Equal lot sizes do not imply equal monetary risk when stop distances or tick values change.
• Keep the account currency explicit in presets and captions. A reference of 10,000 USD is not automatically equivalent to 10,000 EUR; do not merely relabel monetary values.
• Read tick size, loss tick value, volume minimum, maximum and step from the intended broker symbol. Do not use generic pip values for metals, indices or unusual contract sizes.
• Estimate the stop loss for a supported reference volume, preferably checking OrderCalcProfit. Reject missing or invalid prices and currency conversions rather than falling back to an arbitrary size.
• Calculate raw lots from the risk budget and estimated loss per lot. Round down to a valid volume step; rounding to nearest can exceed the intended budget.
• If the minimum lot already exceeds the budget, skip the entry with a recorded reason. Never describe forced minimum-volume trades as maintaining the chosen risk percentage.