Use the same unit
Compare cost per ounce, count or usable load rather than package price alone. Different sizes and concentrated formulas can make a large pack difficult to compare.
Check the conditions
Coupons, subscriptions and loyalty memberships can affect the final price. Look for minimum quantities, renewal prices and cancellation terms before you commit.
Leave room for what you need
Buying in bulk only helps if you can use and store the purchase. Check expiration dates and household needs before adding another multipack.