Account Cushion vs Position Size: The Prop Firm Math
Last verified: 2026-06-02 PDT
Account cushion is the amount of usable room between current equity and the boundary that ends or damages the account. Position size is how much exposure the trader chooses. The mistake is comparing position size to the headline account balance instead of the cushion that actually controls survival.
The simple idea
Account cushion is the amount of usable room between current equity and the boundary that ends or damages the account. Position size is how much exposure the trader chooses. The mistake is comparing position size to the headline account balance instead of the cushion that actually controls survival.
Why headline balance can mislead
A $50,000 evaluation account does not mean the trader has $50,000 of practical risk room. If the drawdown cushion is $2,000, that cushion is the number that matters for sizing. A $300 loss is not 0.6% of the real survival budget; it is 15% of a $2,000 cushion.
The sizing formula
A basic framework is: planned dollar risk per trade equals stop distance times dollar value per point times contracts. Then compare that planned risk to the account cushion. If one trade risks 10% to 20% of the cushion, a normal losing streak can become an account-level event.
Example with futures
Suppose a micro contract risks $5 per point and the stop is 20 points. One contract risks about $100 before costs. With a $2,000 cushion, that is 5% of cushion. Two contracts risk about $200, or 10%. Five contracts risk about $500, or 25%. The market did not become more dangerous. The chosen size changed the account math.
How traders can review it
Before the session, write the current cushion, max personal daily risk, per-trade risk, stop distance, and planned size. After the session, compare planned risk to actual risk. If actual risk was larger, tag why: wider stop, extra contracts, slippage, moving stops, or revenge entries.
Bucko workflow
Bucko fits naturally as a cushion tracker and review workspace. Traders can log the cushion, risk per trade, contract count, and outcome, then review whether size matched the plan. Monko-style automation guardrails can be configured by the user around max size, daily caps, and pause rules where supported.