Free calculators that show their work

Mathmatives answers everyday number questions with fast calculators that show the formula, an example, and never ask you to sign up.

Popular calculators

Salary & Employment

Salary to Hourly Calculator: Turn an annual salary into an hourly wage.
Hourly to Salary Calculator: Turn an hourly wage into annual, monthly and weekly pay.
Overtime Pay Calculator: Calculate time-and-a-half or double-time pay.
Pay Raise Calculator: See what a raise means per paycheck and per year.

Personal Finance

Savings Goal Calculator: How long until you reach a savings target.
Emergency Fund Calculator: Set a 3–12 month emergency fund target.
Debt Payoff Calculator: Payoff time, interest and debt-free date.
Retirement Savings Calculator: Project your nest egg and monthly retirement income.

Home & Real Estate

Mortgage Extra Payment Calculator: Interest and years saved by paying extra.
Rent vs Buy Calculator: Compare true costs of renting vs owning.
Rental Yield Calculator: Gross and net yield on a rental property.

Health & Wellness

TDEE Calculator: Maintenance calories and cut/bulk targets.
Macro Calculator: Calories into grams of protein, carbs and fat.
Water Intake Calculator: Daily water needs from weight and activity.
Sleep Calculator: Bedtimes and wake times by 90-minute cycles.
Pregnancy Due Date Calculator: Due date, weeks pregnant and trimester dates.

Auto & Travel

Fuel Cost Calculator: Trip fuel cost, total and per person.
Car Affordability Calculator: Turn a monthly budget into a car price.

Business & Freelancing

Freelance Rate Calculator: The minimum hourly rate you should charge.
Break-Even Calculator: Units and revenue needed to break even.

Why use Mathmatives?

Every calculator shows its formula. Each page shows how the answer is computed, gives a full example, and lists assumptions and limits.

Nothing stands between you and the answer. Calculators run instantly in your browser, work on any phone, and your inputs never leave your device.

Built for real decisions. Every page adds the context the number needs: what counts as a good rental yield, why minimum payments barely move a credit card balance, and how accurate a due date estimate is.