About CalcLoft

CalcLoft is a small set of fast, focused calculators for the math people actually look up: class grades and GPA, hours worked and weekly time cards, the gap between two times, tips, dates, running pace, and age. Each tool does one job well and puts the answer first.

How the math is checked

Every calculator is backed by a plain function with a unit test. Before anything ships, those tests run the formulas against hand-checked examples — a weighted grade, a 40-plus-hour week with overtime, a tip split three ways — and the build fails if a single number is off. The formula behind each tool is printed right on its page so you can verify it yourself.

Fast and private

The whole site is static and every calculation runs in your browser. Nothing you type is uploaded, stored, or shared, there is no signup, and the calculator sits at the top of the page instead of behind ads. Spotted a wrong result? Tell us on the contact page and it gets fixed.

Scope

These are everyday, non-medical, non-financial tools. We deliberately don't publish health or money-advice calculators; for grading, cutoffs follow the common US scale, which your school may adjust.