Free Online Calculator Tools

18 purpose-built calculators for money, health, home and everyday math

A general-purpose calculator makes you remember the formula; a purpose-built one just asks for the inputs you already know. That's the idea behind this category: each calculator handles one real-life computation — a restaurant tip, a mortgage payment, a body-mass index, a semester GPA — with the formula, units and edge cases built in.

Every calculator computes instantly in your browser as you type. None of your numbers — not your salary, weight, due date or loan amount — are sent anywhere, which makes these tools appropriate for genuinely personal math. They're free, unlimited and work identically on desktop and mobile.

All Calculator Tools at a Glance

What Each Tool Does

Every tool below opens instantly, needs no account, and processes your data locally in your browser. Here is what each one is for:

BMI

Body Mass Index from height and weight, in metric or imperial, with the standard WHO category ranges for context. Open the BMI →

Tip

Work out the tip and per-person total for any bill and service level — solves the end-of-dinner math instantly. Open the Tip →

Percentage

Percentages in every direction: X% of Y, what percent X is of Y, and percentage increase or decrease between two numbers. Open the Percentage →

Discount

See the final price and actual savings for any discount — including stacked percent-off deals. Open the Discount →

Sales Tax

Add or back out sales tax and VAT from any amount, at any rate — useful for quotes, invoices and receipts. Open the Sales Tax →

Mortgage

Monthly payment, total interest and amortization for a home loan from principal, rate and term. Open the Mortgage →

Compound Interest

Watch savings or investments grow with compounding — with adjustable contribution, rate and frequency. Open the Compound Interest →

Calorie

Estimate daily calorie needs from age, size and activity level using the standard Mifflin-St Jeor equation. Open the Calorie →

Fuel Cost

Estimate what a trip will cost from distance, fuel efficiency and fuel price — before you commit to the drive. Open the Fuel Cost →

Split Bill

Divide a bill fairly among any number of people, tip included — the group-dinner peacekeeper. Open the Split Bill →

Scientific

A full scientific calculator in the browser: trigonometry, logarithms, powers, roots and parentheses. Open the Scientific →

GPA

Calculate a weighted GPA from your courses, credits and grades — check your standing before the transcript arrives. Open the GPA →

Body Fat

Estimate body fat percentage from tape measurements using the US Navy method. Open the Body Fat →

Pregnancy

Estimated due date and week-by-week milestones from your last period or conception date. Open the Pregnancy →

Ovulation

Predict fertile days and the next ovulation window from your cycle length and last period. Open the Ovulation →

Hours

Add up hours and minutes between times — timesheets, shift lengths and overtime without spreadsheet fuss. Open the Hours →

Carpet

Convert room dimensions into the carpet area you need to buy, with allowance for waste. Open the Carpet →

Paint

Estimate how many liters or gallons of paint a room needs from wall dimensions and coats. Open the Paint →

How to Choose the Right Tool

For money questions, reach for the Percentage, Discount, Sales Tax, Tip or Split Bill calculators for quick arithmetic, and Mortgage or Compound Interest for longer horizons. Health and body calculators — BMI, Body Fat, Calorie, Pregnancy and Ovulation — estimate widely used medical formulas (always as guidance, not diagnosis). The Hours Calculator and GPA Calculator handle work and school bookkeeping, while Carpet and Paint calculators translate room dimensions into shopping quantities. The Scientific Calculator covers everything with trigonometry, logs and powers, and Fuel Cost estimates what a trip will really cost.

Frequently Asked Questions

Are the health calculators medically reliable?

They use standard published formulas (like BMI and the Mifflin-St Jeor equation) that are useful for orientation, but they're not a substitute for professional medical advice.

Are my numbers stored or transmitted?

No. Every calculation runs locally in your browser — nothing you enter is uploaded or logged.

Do the financial calculators account for taxes and fees?

They compute the standard formulas (amortization, compound interest, percentages). Local taxes or bank fees vary, so treat results as close estimates.

Can I use these calculators on mobile?

Yes — all calculators are responsive and designed for quick one-handed use on phones.

Explore More WiserWork Categories

WiserWork offers 295 free browser-based tools across 22 categories — all private, all free, no sign-up required.