The basic formula
Tip amount = bill amount x tip percentage / 100. If the bill is 80 and the tip rate is 15%, the tip is 80 x 0.15 = 12. The total is 92.
Splitting the bill
To split evenly, add the tip to the bill and divide by the number of people. If people ordered very different amounts, calculate each person's share first and apply the tip to each share.
Before-tax or after-tax?
Some people tip on the pre-tax subtotal; others tip on the final bill. The calculator needs to make the base amount explicit. If the bill includes tax or a mandatory service charge, check whether you want to tip on top of that amount.
Common edge cases
- Service charge: a mandatory service charge may already be included.
- Discounts: decide whether the tip should be based on the original price or discounted price.
- Rounding: round the total or per-person amount in a way that is easy to pay.
- Local customs: tipping expectations vary by country, venue and service type.
Tip calculation examples
For a 68.40 bill, an 18% tip is 12.31 and a 20% tip is 13.68. With four people splitting the 20% total, each person pays 20.52 because (68.40 + 13.68) / 4 = 20.52.
You should be able to choose whether the tip is based on the pre-tax amount, post-tax amount or a subtotal after discounts. It should also handle service charges separately, since a fixed service charge may or may not replace an optional tip depending on local practice and the bill wording.
Useful calculators
FAQ
How do I calculate 20% quickly?
Move the decimal one place left to get 10%, then double it.
Should I tip before or after tax?
That is a choice and may depend on local custom. The important part is to know which bill amount you used.
How do I split a bill with different orders?
Calculate each person's subtotal, apply the tip percentage to each subtotal, then add shared charges separately if needed.
Last reviewed: 2026-05-16.