You can easily put all your information in for players and calculate those tough battles down to a T. You type in your monsters and how many experience points they are worth and the quantity along with how many players you have and there level, and it gives you a clean read out for how difficult the encounter would be.
The challenge rating is calculated on several factors already put into the excel sheet for easy encounter crafting. This factors in the multiple Monster modifier for 5e, as well as when the group has a party greater then 6. Party greater then 6 add +1 to the Challenge and greater than 8 add another +1, and at 10 it adds one more +1 modifier to the party challenge rating.
In the pathfinder encounter chart you basically have the same thing but the multiplier is always 1 however you can change the conditions to add a favorable/geared or unfavorable modifier to the Challenge rating. You can also just role with the standard of none. The choice is yours. Really easy to put what you need in and go to battle.