Quick Mental Maths Methods

  1. 1

    Find 10% first

    Move the decimal one place to the left. On a $85 bill, 10% = $8.50. This is your baseline for calculating any tip percentage quickly.

  2. 2

    Scale up from 10%

    15%: find 10% ($8.50) and add half of that ($4.25) = $12.75. 20%: double the 10% ($8.50 × 2 = $17.00). 18%: find 10% ($8.50) + 5% ($4.25) + 3% (roughly $2.55) = $15.30. For most people, rounding to the nearest dollar is perfectly acceptable.

  3. 3

    Using your phone

    Bill amount × 0.10 = 10% tip. Bill × 0.15 = 15% tip. Bill × 0.18 = 18%. Bill × 0.20 = 20%. Simply multiply. Example: $85 × 0.18 = $15.30 tip. Total: $100.30.

Splitting the Bill with a Tip

  1. 4

    Add the tip first, then split

    Add the tip to the total first, then divide by the number of people. Example: $120 bill, 20% tip, 4 people. Tip = $24. Total = $144. Per person = $36. This is fairer than splitting the food bill and each person calculating their own tip separately.

Common Tip Percentages at a Glance

  • 10%: Minimum for acceptable service
  • 15%: Standard for good service
  • 18%: Often the default on restaurant point-of-sale prompts
  • 20%: Excellent service or rounding up for convenience
  • 25%+: Exceptional service
Tipping in AustraliaTipping is not as culturally expected in Australia as in the United States. Restaurant workers in Australia are paid standard wages (unlike the US where tips make up a substantial portion of income). Tipping is appreciated but genuinely optional for table service, and not generally expected at cafes or takeaway. Rounding up or leaving a few dollars for good service is the common approach.

Frequently Asked Questions

Convention in most countries is to tip on the pre-tax subtotal, as you are tipping for the service, not the government tax. In practice, the difference is small (on a $100 bill, the tip difference between pre- and post-tax at 18% is under $2) and most people simply tip on the total shown on the bill without worrying about it.
For app-based delivery (DoorDash, Uber Eats, Deliveroo): $3–5 is a reasonable minimum for a standard delivery. For large orders, bad weather, or a long delivery distance, $5–10 is appreciated. In Australia, delivery fees already include a component for the driver, but tips are appreciated and go directly to the driver.