Shared costs: split by everyone
Lodging, groceries and anything bought for the whole group split evenly among everyone on the trip, skiing or not.
Personal costs: paid by the person
Lift tickets and rentals are usually bought per person. If one person buys them for the group, add each as its own expense split among the people it was for. Leaving non-skiers out of lift tickets is an easy fairness fix.
Use your real prices
Lift ticket and rental prices vary a lot by resort, date and how far ahead you buy. Check the resort's own site for your dates and enter those numbers.
Keep the trip on one tab
Turn the result into a tab and the shared lodging and food are added for you. Add lift tickets and rentals for the people they're for, and GroupTab works out a short list of payments at the end.
GroupTab keeps everyone's Venmo and Cash App in the tab, so paying is one tap with the amount already filled in, and both sides confirm when it arrives.