CalcKit

Guides

Formulas and rounding rules for each calculator.

• How a tip calculator splits a bill

  Tip amount, total, and per-person rounding — the same math CalcKit uses.

• How an equal bill split works

  Same share for everyone, optional tip, and how leftover cents are handled.

• Margin vs markup

  Why 25% margin is not 25% markup, and how sell price is derived from cost.

• Three percentage problems

  X% of Y, “what percent is X of Y”, and percent change — including zero and negatives.

• How a percent-off price is calculated

  Savings and final price from an original amount and a percent off.

• Hourly to annual (and back)

  Gross pay from hours per week and weeks per year. Estimate only — not take-home.