Tip Calculator — Bill Splitter with Country Presets

Tipping is a single multiplication, but it gets messy when a tax line and a group split are involved. This calculator wraps the three pieces of math you actually need — tax, tip, and per-person split — into one deterministic formula and shows each component separately so you can verify it by eye.

1. Tax amount = bill × tax% ÷ 100. Zero if you switch the tax line off.
2. Tip base = bill (pre-tax) or bill + tax (post-tax), depending on your selection.
3. Tip amount = tip base × tip% ÷ 100.
4. Total = bill + tax amount + tip amount.
5. Per person = total ÷ number of people. If round-up is on, each share is rounded up to the next whole unit and the overage is shown beside it.

Internally the calculator cross-checks against the closed-form identity total = bill × (1 + tax/100 + tip/100 × basis), where basis is 1 for pre-tax tipping and (1 + tax/100)for post-tax. Both routes return the same number to the cent — that's the "cross-check verified" badge in the card header.

Country presets pull from Wise's tipping guide and Condé Nast Traveler's country reference (both linked in Sources). Sri Lanka's 18 % VAT comes from the Value Added Tax (Amendment) Act No. 32 of 2023 via the Inland Revenue Department. Customary tipping rates change slowly; the constants here are reviewed annually and marked with a LAST_VERIFIED date in the source file.

• Wise — Tipping around the world: who, when, and how much
• Condé Nast Traveler — Tipping guide for travellers
• IRD — Sri Lanka VAT (18% standard rate)
• U.S. Bureau of Labor Statistics — Tipped occupations reference

Country tipping conventions and tax rates were last cross-checked against the above sources on 2026-05-11. The page is reviewed annually and whenever a VAT/GST headline rate changes.