How to Calculate a Restaurant Tip in Your Head (4 Easy Methods)
No app needed. These four mental math tricks work for any bill at any tip percentage.
Method 1 (the 10% anchor): Find 10% by moving the decimal point left once. 10% of $67.40 = $6.74. For 20%: double it = $13.48. For 15%: add half = $6.74 + $3.37 = $10.11. For 25%: multiply by 2.5 = $16.85. This method handles every common tip percentage from one anchor calculation.
Method 2 (double the tax): In many states, sales tax is 7-10%. Double the tax amount to get approximately 15-20%. A $5.50 tax × 2 = $11 tip (roughly 18-20% on most bills). This works without any math on the bill total — just look at the tax line.
Method 3 (the round-up): Round the bill to the nearest $10, then calculate. $67.40 becomes $70. 20% of $70 = $14. Close enough and takes 2 seconds. Method 4 (per person): For group dinners, figure $5-8 per person as a rough tip estimate (works for moderate-priced restaurants). Ten people at dinner: $50-80 tip covers 18-20% on most tabs.