Calculators

Age, BMI, ROI, tips, and more.

Quick calculators for age, BMI, BMR, TDEE, ROI, tips, and more. Each tool does one job well and works on mobile and desktop. No account or installation needed.

This category is for quick, single-purpose calculations: age, BMI, BMR/TDEE, tips, ROI, unit price, fuel cost, payroll hours, and similar everyday math. Aimed at individuals checking numbers for personal or light professional use.

Common tasks include working out a tip and split, comparing unit prices at the shop, estimating trip fuel cost, converting timesheet hours to decimals, estimating daily calories (TDEE), or seeing how an investment performs as a simple ROI. Each tool does one job and runs in the browser with no account.

Choose by what you are calculating: age in years/months/days, body metrics (BMI, BMR, TDEE—informational only), money (tip, percent change, ROI, unit price), time (hours to decimal), or trip costs. For full mortgages or multi-year compound savings, see Money & Finance.

Read the assumptions on each tool page. Health and finance numbers are estimates for personal exploration; they are not medical, tax, or lending advice.

Related guides

Calculators tools

  • Age Calculator

    Calculate exact age in years, months, and days from a birth date to today or any chosen end date.

    Open Age Calculator

  • BMI Calculator

    Calculate adult Body Mass Index (BMI) from metric or imperial height and weight and view common category bands.

    Open BMI Calculator

  • BMR & TDEE Calculator

    Estimate Basal Metabolic Rate (BMR) and daily energy needs (TDEE) with the Mifflin–St Jeor equation and activity multipliers.

    Open BMR & TDEE Calculator

  • Fuel Cost Calculator

    Estimate trip fuel cost from distance, vehicle efficiency (L/100 km or MPG), and fuel price so you can budget road trips, commutes, and vehicle comparisons before you drive.

    Open Fuel Cost Calculator

  • Hours to Decimal Calculator

    Convert hours and minutes to decimal hours—and back—for payroll timesheets, freelance invoices, and billing systems that multiply time by an hourly rate.

    Open Hours to Decimal Calculator

  • Loan Payment Calculator

    Compute the fixed monthly payment, total interest, and amortization summary for an installment loan so you can see how rate and term drive cost before you commit.

    Open Loan Payment Calculator

  • Mortgage Affordability Calculator

    Estimate a rough maximum home price or loan size from your income, monthly debts, down payment, interest rate, and basic housing-cost assumptions using common debt-to-income heuristics.

    Open Mortgage Affordability Calculator

  • Percent Change Calculator

    Measure relative growth or decline between two values, or apply a percentage increase or decrease to a starting number.

    Open Percent Change Calculator

  • ROI & CAGR Calculator

    Compute simple return on investment (ROI) and a smoothed annualized rate (CAGR) over a stated time horizon.

    Open ROI & CAGR Calculator

  • Tip Calculator

    Calculate tip amount, bill total with gratuity, and even per-person splits for dining, delivery, and services.

    Open Tip Calculator
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