The one rule that holds almost everywhere tipping exists at all: the tip is calculated on the pre-tax subtotal, not on the total after tax is added. Sales tax is money the restaurant collects on behalf of the government, not revenue the server had any part in earning — tipping on top of it quietly inflates the tip by whatever the local tax rate happens to be, which several sources specifically flag as a common visitor mistake in Canada and the US. This tool always computes the tip from the subtotal you enter, then adds tax separately, so the two never get tangled together by accident.
A $80.00 bill with 8% tax and a 20% tip: the tip is $16.00 (20% of $80, not 20% of $86.40), tax is $6.40, and the grand total is $102.40 — split evenly three ways, that's $34.13 each.
Split unevenly instead — say one person ordered $22.50, another $35.00, another $12.50 (the same $70 subtotal split differently) — and each person's tax and tip scale with what they actually ordered: the $35 order carries $2.80 of tax and $7.00 of tip, the $12.50 order carries $1.00 and $2.50, summing back to the exact same grand total either way.
Multiple 2026 tipping guides note that 15% — long the textbook "standard" — now reads as a sign something went wrong; 18–20% has become the baseline for ordinary good service, with 22–25% reserved for genuinely excellent service. This tool's US/Canada presets reflect that shift rather than the older, lower figures still repeated in a lot of older advice.
No — it's the actual, well-documented difference. Service staff in the UK and most of Western Europe are paid at least a legal minimum wage regardless of tips, and in many cases a 10–12.5% "service charge" is already added to the bill before you'd add anything else. Always check the bill first; if a service charge is already there, an additional tip is a bonus, not an expectation.
Genuinely different, not just a lower number — tipping isn't customary and can come across as odd or even mildly insulting, since excellent service is considered the cultural standard rather than something that warrants extra payment. The regional note for this preset says so directly rather than suggesting a percentage that doesn't apply.
Because "evenly" quietly overcharges whoever ordered less and undercharges whoever ordered more — fine among close friends who don't mind, but not actually fair when a table has very different orders. Proportional splitting means everyone's share of tax and tip matches their share of what was actually ordered, verified to sum back to the exact same grand total as splitting evenly would.