The NumberTrove library
Free online calculators for
real-life decisions.
Pick a topic, open a tool, and get an answer you can check.
Home & build
Plan quantities for concrete, paint, flooring, landscaping, and more.
11 calculators ↗Shipping & logistics
Understand volume, dimensional weight, pallets, and containers.
10 calculators ↗Energy
Turn watts, hours, and rates into a cost you can act on.
33 calculators ↗Health & fitness
Estimate everyday health and fitness measures with clear assumptions.
6 calculators ↗Work & pay
Compare hourly and annual pay, overtime, days, and hours.
6 calculators ↗Business
Make margin, markup, ROI, break-even, and growth easier to see.
12 calculators ↗Everyday math
Useful answers for percentages, dates, ratios, averages, and more.
20 calculators ↗Converters
Move between common metric and imperial units without the noise.
11 calculators ↗Find a calculator by what you are trying to solve
Choose a focused calculator category above. Each page explains the relevant formula, units, assumptions, and related tools so you can get an answer and understand where it came from. Every calculator is free, runs in your browser, and needs no account.