Tip Calculator

Working out a tip and splitting a bill are two operations that people do at the worst possible moment: after a meal, in bad light, in a hurry. The calculator above does both at once and keeps the arithmetic visible, so you can check it rather than trust it.

How it works

Enter the bill amount, choose a tip percentage — 10%, 15% and 20% are one tap away, or type any other figure — and set the number of people sharing. Three results update as you type:

• Tip — the bill multiplied by the percentage, divided by 100.
• Total — bill plus tip.
• Per person — the total divided by the number of people.

Each is rounded to the nearest cent. The number of people must be a whole number of at least one, so 2.5 people is refused rather than producing a result nobody can pay. A 0% tip is valid and returns the bill unchanged. Negative amounts are rejected.

Note that the per-person figure is the total divided by the headcount, not the tip alone. This is what you want when everyone is paying an equal share of the whole bill; if you are splitting only the tip on top of individually paid items, divide the Tip figure by hand instead.

Getting the split right

Rounding creates a shortfall. A total of 100.00 split three ways gives 33.33 each, which sums to 99.99. The missing cent has to come from somewhere, and the conventional fix is for one person to round up. The tool deliberately does not hide this by inflating every share: it shows the honest per-person figure, and leaves the rounding decision to the table.

Tip on the pre-tax or post-tax amount? Both conventions exist, and they differ by the tax rate times the tip rate — on a 100 bill with 20% tax and a 20% tip, that is 4. The tool applies the percentage to whatever you type, so enter the pre-tax subtotal if that is your convention.

Service charge is not a tip. If a service charge is already on the bill, it is part of the bill amount, and adding a percentage on top tips twice. Subtract it before entering the figure if you want to tip on the food alone.

Percentages of percentages. A 20% tip is a fifth, so the fast mental check is: move the decimal one place left, double it. On 47.50 that is 4.75, doubled to 9.50 — which is what the tool should show.

What happens on the card

When you add a tip on a card terminal or write one on a slip, the amount that was authorised at the point of sale is usually not the amount that gets settled. The merchant authorises the bill, then captures a higher amount, or sends an incremental authorisation — which is why a tipped transaction can show one figure as pending and a different one on the statement two days later, and why some issuers pre-authorise an extra 20% headroom. The mechanics of authorisation, capture and settlement are covered in card payments, and the wider picture of how amounts, currencies and minor units are represented across a payment flow is in payment systems fundamentals.

For the same calculation with the sign reversed — taking a percentage off rather than adding one on — use the discount calculator, and for arbitrary percentage questions the percentage calculator handles all three directions.