The notional value of one contract is 50 times the value of the S&P 500 stock index. On last Friday, S&P 500 cash index closed at 2,800, making each E-mini contract a 50 * 2,800 = $140,000 bet.
If the average volume is 1.6~2M, the implied dollar value of ES mini is 1.6~2M * $140K. If you add the original (big) S&P contract, > $100B are traded every day.
