The difference between E-mini and Micro
ES is the E-mini S&P 500 future, worth 50 USD per point per contract. MES is the Micro E-mini, worth 5 USD per point. Both have a tick size of 0.25 points, so one tick is worth 12.50 USD for ES and 1.25 USD for MES.
Position size is expressed in whole contracts. You cannot enter 0.2 ES contracts as though they were Forex lots. When the budget does not allow one ES, the Micro offers a different level of risk granularity, but it still needs to be assessed with its own costs.
From a 5-point stop to 20 ticks
Divide the distance by the tick size: 5 ÷ 0.25 = 20 ticks. The loss before costs is 20 × 1.25 = 25 USD per MES, or 20 × 12.50 = 250 USD per ES. With a budget of 100 USD, the calculation without costs gives 4 MES and zero ES.
A distance of 5.01 points does not correspond to a whole number of ticks. The calculator rounds it up to 21 ticks, or 5.25 points, to avoid underestimating risk. The distance is rounded up; the number of contracts is rounded down.
Commissions can change the number of contracts
Take the MES with a 20-tick stop and add a hypothetical round-trip commission of 2 USD per contract. Risk rises to 27 USD per contract; with a budget of 100 USD, the result falls from 4 to 3 contracts. Four contracts would require an estimated risk of 108 USD.
If you also include one tick of total slippage, the cost per contract becomes 28.25 USD and the estimated loss for 3 contracts is 84.75 USD. The remaining 15.25 USD is unused because it is not enough for another contract.
Risk, margin and historical data
The margin required by the broker is a separate check. Three contracts fitting within the stop-loss budget does not show that the account has enough margin to open them. The tool does not send orders or check the balance available in your trading platform.
For a backtest, use the ES or MES entry in the catalogue and check its start date. Do not assign the E-mini’s entire history to the Micro. Keep expiry, session and rollover handling explicit when interpreting price movements.
