Calculators

25 straightforward calculators that show their formulas and work instantly as you type.

Money & finance

Mortgage CalculatorMonthly mortgage payment with property tax, insurance, HOA and PMI.
Loan CalculatorMonthly payment, total interest and a full amortization schedule.
Compound Interest CalculatorSee how savings grow with compounding and monthly contributions.
Hourly to Salary CalculatorConvert hourly wage to annual, monthly and weekly pay — and back.
Sales Tax CalculatorAdd sales tax or VAT to a price, or extract it from a tax-inclusive total.
Discount CalculatorSale price and savings, including stacked discounts and sales tax.
Tip CalculatorWork out the tip and split the bill between any number of people.
Profit Margin & Markup CalculatorMargin, markup, profit and selling price from cost and price.

Math

Percentage CalculatorX% of Y, what percent, percentage change and increase/decrease.
Fraction CalculatorAdd, subtract, multiply and divide fractions and mixed numbers, simplified.
Scientific CalculatorTrig, logs, powers, roots, factorials and constants with history.
Mean, Median, Mode & Standard DeviationAverage, median, mode, range, variance and standard deviation of a data set.
Aspect Ratio CalculatorFind width or height for a ratio like 16:9, or simplify any resolution.
Roman Numeral ConverterConvert numbers to Roman numerals and back, with validation.
Random Number GeneratorRandom numbers in any range, with or without repeats, or shuffle a list.

Dates & time

Date Difference CalculatorDays, weeks, months and business days between two dates.
Add or Subtract Days from a DateFind the date N days, weeks, months or business days from any date.
Age CalculatorExact age in years, months and days, plus days to your next birthday.
Hours & Time Card CalculatorAdd up hours worked from start and end times, minus breaks, for a week.
Time Zone ConverterConvert a time between cities and time zones, with daylight saving.

Health, school & units

BMI CalculatorBody Mass Index in metric or imperial units, with the WHO category.
Calorie Calculator (BMR & TDEE)Estimate daily calorie needs from BMR and activity level.
Running Pace CalculatorPace, time or distance for runs, with race finish-time predictions.
GPA CalculatorCalculate your semester or cumulative GPA on the 4.0 scale.
Unit ConverterLength, weight, temperature, volume, area, speed, data and time.

Calculators you can check

Each calculator states the formula it uses — for example the standard amortization formula for loans and mortgages, the Mifflin–St Jeor equation for calorie needs, and the Riegel formula for race-time predictions — so you can verify results yourself. Exact arithmetic is used where rounding would mislead, such as fractions.

Results are estimates for planning, not financial, tax or medical advice. Check important decisions with a qualified professional.

Frequently asked questions

Are these calculators accurate?

They use standard published formulas and double-precision math, rounded only for display. Financial results can differ slightly from a lender’s figures because of fees and rounding rules.

Do you store what I enter?

No. Calculations run in your browser and nothing is sent or saved.

Can I use them on my phone?

Yes. Every calculator is designed for small screens and works in any modern mobile browser.