The NumberTrove library
Free online calculators for
real-life decisions.
Find practical tools for home projects, paychecks, shipments, energy bills, business decisions, health estimates, conversions, and everyday math.
Find a calculator by what you are trying to solve
Choose a focused calculator category below. Each page explains the relevant formula, units, assumptions, and related tools so you can get an answer and understand where it came from.
Home & build
Plan quantities for concrete, paint, flooring, landscaping, and more.
10 calculators ↗Shipping & logistics
Understand volume, dimensional weight, pallets, and containers.
8 calculators ↗Energy
Turn watts, hours, and rates into a cost you can act on.
11 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.
5 calculators ↗Business
Make margin, markup, ROI, break-even, and growth easier to see.
9 calculators ↗Everyday math
Useful answers for percentages, dates, ratios, averages, and more.
11 calculators ↗Converters
Move between common metric and imperial units without the noise.
2 calculators ↗