ES at 1067.50, contract worth $53,375
YM at 10014, contract worth $50,070
For the 6.6% difference in contract value intraday spreaders just trade 1 to 1, not 5 ES to 6 YM. For position trading it would be 15 ES to 16 YM at current prices.
Here is a CME writeup from 2008...