Contract Size
The fixed quantity of the underlying asset controlled by one futures contract, set by the exchange.
Notional Value = Contract Size × Futures Price
Contract size (also called contract unit) defines exactly how much underlying one futures contract represents. It is non-negotiable — the exchange standardizes it so that all market participants trade identical units.
Common contract sizes: ES = 50× the S&P 500 index; NQ = 20× Nasdaq-100; CL = 1,000 barrels of crude oil; GC = 100 troy ounces of gold. The micro versions (MES, MNQ, MCL, MGC) are exactly one-tenth of the standard.
Multiplying contract size by the futures price gives the full notional value — the economic exposure you carry per lot.
On the desk
CL (WTI crude) has a contract size of 1,000 barrels. At $80/barrel the notional exposure per contract is $80,000. A $1 move in crude = $1,000 P&L per contract.