Tip, Sales Tax & Group Bill Split Calculator

The arithmetic, written out

On this page's defaults: a 120 subtotal with 8.5% tax adds 10.20, the 18% tip on the pre-tax subtotal is 21.60, and the total is 151.80 — 37.95 each across four people, which happens to divide exactly.

• Sales tax = subtotal × (tax rate ÷ 100)
• Tip base = subtotal (pre-tax) or subtotal + tax (post-tax)
• Tip = tip base × (tip rate ÷ 100)
• Total = subtotal + tax + tip
• Per person = total ÷ number of people, with remainder cents distributed

Tip on the pre-tax or post-tax amount?

Conventional guidance is to tip on the pre-tax subtotal: you are rewarding the service, not paying gratuity on a government levy. The difference is small on a single meal — around 1.7 percentage points of bill on a 10% tax — but it is the reason the toggle exists, and both conventions are used in practice.

Either way, be deliberate. The tool defaults to pre-tax and shows the tax separately so you can see exactly which base produced the number.

What a tip percentage means in practice

Tipping norms are regional, not universal, and the tool does not assume them. Widely used US ranges run from around 15% for acceptable service to 20–22% for excellent service, with counter service and takeaway usually treated differently from table service. In many countries tipping is discretionary or already included, and the correct rate may be zero.

Treat any percentage here as a convention rather than a rule, and check the bill before adding anything.

Check for an auto-gratuity first

Larger parties frequently have a service charge or auto-gratuity already added — commonly 18% or 20%. Look for 'service charge', 'auto-gratuity' or 'large party fee' on the itemised bill before working out a tip on top of it, or you will pay twice for the same service.

If it is already there, enter the subtotal as normal and set the tip rate to zero to see the true total, or set a tip rate that reflects what you want to add on top.

Why splitting a bill is harder than dividing

Dividing money by a party size rarely produces an exact figure. A 100 bill across three people gives 33.333… each, and rounding each share to 33.33 leaves a cent unaccounted for — the shares no longer add up to the total, which is exactly the sort of thing that starts an argument at the table.

This calculator distributes the remainder cents rather than rounding each share independently, so the individual amounts sum precisely to the grand total and it tells you how many people pay the slightly larger share. That means you can show the summary and every payment will reconcile.

Uneven splits

An even split assumes everyone consumed roughly the same value. Where that is obviously untrue — one person had the steak and two shared a starter — the fair approach is to split the shared items and add each person's own items, then divide the tax and tip in proportion to what each person ordered.

This page splits evenly, which is the common case. For mixed orders, use it to get the tax and tip proportion right, then adjust the individual subtotals before entering them.

Currency

The arithmetic is currency-neutral: the same numbers work in USD, GBP, EUR, ZAR, AUD or anything else, and the selector changes the symbol so the summary reads correctly when you pass a phone around the table. No exchange rates are involved, because none are needed.