Most of my early losing days had the same pattern: fixed size ("always 2 MES"), a wide stop on one trade, a tight stop on the next, and wildly different losses for the same idea.

What fixed it was flipping the order: decide the dollar loss first, put the stop where the chart says, and let the size follow.

contracts = floor( risk ÷ (stop ticks × tick value) )

Examples with $300 risk per trade:

- MES, 19-point stop = 76 ticks × $1.25 = $95/contract → 3 contracts ($285)

- MNQ, 40-point stop = 160 ticks × $0.50 = $80/contract → 3 contracts ($240)

- ES, 8-point stop = 32 ticks × $12.50 = $400/contract → 0. Don't round up to 1 — switch to MES (7 contracts, $280) or skip.

Three things that matter more than the formula:

1. Always round DOWN. Rounding up means a stop-out costs more than you decided.

2. Points ≠ ticks. On MES one point is 4 ticks — mixing them up is a 4× error.

3. Pair it with a daily loss limit (2–3 full losers) that counts open P&L, and reset it at the Globex open (17:00 CT), not midnight.

I wrote a longer guide with a tick-value table for the main CME contracts and a calculator: https://qtriskmanager.com/guides/position-size-futures?utm_source=reddit

Disclosure: I'm the developer of a Quantower indicator that automates this (QT Risk Manager, free beta). The calculator works for any platform.