One handy place for the numbers you reach for all day.
Measurements, money, projects, HVAC, electrical, plumbing, paint, and everyday conversions — all free, no sign-up required.
Free calculators that show their work
Calculator Caddy is a growing library of 88 free online calculators covering finance, health, construction, measurement, and everyday math. Every tool is designed to do three things: give you a fast, accurate answer, explain the method behind it, and work on any device — with no pop-ups and no sign-up.
We built Calculator Caddy because we were tired of calculator sites that hide the math and bury the tool under ads and logins. Here, the calculator is the first thing you see, and a plain-English explanation shows how the result was reached — so you can trust it and understand it. Learn more about us.
Calculator Caddy tool shelf
Quick Amazon searches for supplies, calculators, and jobsite tools that pair naturally with the calculators in this app.
As an Amazon Associate, Calculator Caddy earns from qualifying purchases. Other product links may also earn a commission.
Browse by Category
Find the right calculator for any task — from mortgage payments to paint estimates.
Finance Calculators
Mortgage, car payment, amortization, lease, debt ratios, paycheck, and tax calculators.
Everyday Calculators
Percentage, shopping discounts, tip splitting, and date/business day calculators.
Life & Health Calculators
Age, pregnancy due date, target heart rate, and calorie recommendation calculators.
Measurement & Converter Tools
Smart measurement, fraction/decimal converters, area, volume, and liquid converters.
Construction & Trade Calculators
Paint, HVAC airflow, electrical, plumbing, and other trade-specific calculators.
Math & Science Calculators
Statistics, algebra, number conversions, GPA, grade, and science calculators.
Why Use Calculator Caddy?
Calculator Caddy provides free, accurate, and easy-to-use calculators for professionals and everyday users alike. All calculations run instantly in your browser — no data is sent to any server.
Instant Results
Calculations update as you type — no button to press, no waiting.
Private & Secure
All calculations happen in your browser. No data is collected or stored.
Works Everywhere
Optimized for desktop, tablet, and mobile. Use it anywhere, anytime.