The total notional value or quantity of the underlying asset represented by one futures contract. Contract size determines how much market exposure each contract provides and varies significantly between instruments and their micro/mini/standard variants.
Why It Matters
- 1Contract size determines your real market exposure and how much a price move will cost or earn you in dollar terms.
- 2In prop trading, understanding contract size helps you select the right instruments for your account size and risk tolerance.
- 3Trading a full ES contract ($50/point) on a $25,000 account is very different from trading a Micro ES ($5/point) — both trade the same market, but the dollar impact per point differs by 10x. Choosing the wrong contract size relative to your account is one of the fastest ways to breach drawdown limits.
Example
- 1One full-size S&P 500 futures contract (SP) is worth $250 x the index value.
- 2At S&P 4,500, one contract controls $1,125,000 in notional value.
- 3The E-mini (ES) is 1/5th the size at $50 x index = $225,000 notional.
- 4The Micro E-mini (MES) is 1/10th of ES at $5 x index = $22,500 notional.
- 5On a $50,000 prop account, trading 1 MES contract represents modest leverage, while 1 ES contract represents significant leverage.
Common Mistakes
- ✖Trading full-size contracts when micro contracts would be more appropriate for the account size
- ✖Not understanding the relationship between contract size and point value
- ✖Assuming contract sizes are the same across different exchanges or instruments