Health and Fitness
Body weight, calories, and related measures. Results are estimates for information only, not medical advice.
Simple calculators, explained in plain words
Simple online calculators with clear explanations. Pick a tool below or search by name. Each page pairs a fast calculator with the formula, a worked example, and short answers.
Browse by group
14 groups keep the library easy to scan as it grows.
Finance and Money
Loans, interest, tips, and discounts. Each page shows the exact formula so you can check the math.
Math and Percent
Short everyday math: percent change, parts of a whole, and ratios.
Everyday Life
Age, dates, fuel use, and other day to day numbers.
Unit Converters
Length and temperature conversions with the exact factors used.
Sports and Pace
Running pace, speed, and race time estimates.
School and Grades
GPA, final exams, and class grades, with each step shown.
Home and DIY
Concrete, paint, and other project quantities for houses and gardens.
Biology and Life
Genetics, growth, and animals. Simple models with the formula shown.
Chemistry and Lab
Molarity, pH, dilutions, and water chemistry with worked steps.
Food and Cooking
Recipes, ratios, roast times, and kitchen numbers that scale.
Physics and Energy
Motion, force, energy, and circuits from first principles.
Technology and Net
Downloads, data sizes, networks, and security numbers.
Other Tools
Dice odds, lottery math, dates of note, and everything else.
Start with these
The most used tools right now.
3D Distance Calculator
Straight and grid distance between 3D points.
401(k) Early Withdrawal Calculator
401(k) early payout cost with penalty, tax, withholding, and exceptions.
401(k) Match Calculator
Free employer match and yearly total from salary and percents.
52 Week Savings Challenge Calculator
Turn a weekly base and week count into challenge total and deposit schedule.
529 Tax Deduction Calculator
529 state tax saving from contribution and cap.
A1C to Blood Sugar Calculator
Average glucose in mg/dL and mmol/L from A1C percent.
Acceleration Calculator
Acceleration from velocity change and time, with force check.
Active Minutes Calculator
Weekly activity versus the 150 minute goal with strength check.
Added Sugar Calculator
Teaspoons, daily limit share, and calories from added sugar grams.
Why trust a result here?
Every page names its formula, shows each step of one full example, and links to outside sources. Read how we verify before you rely on a number for money or health.