All Free Online Calculators

Simplest aspect ratio and the matching height for a new width.

Estimate password entropy from its length and character set.

Total trip cost from lodging, food, transport, activities, and flights.

Convert money with your own exchange rate and fee.

Convert a nominal APR into the effective annual yield.

Discount future cash flows to see if an investment is worth it.

Find how much cash cushion you need and how long it takes to build.

Add up assets and debts to see your net worth.

See how much interest and time extra monthly payments save.

Estimate how much rent fits your income.

Find your CAC and compare it with customer lifetime value.

Measure customer churn, retention, and expected lifetime.

See how many times you sell through stock each year.

Find the order size that minimizes ordering and holding costs.

Estimate BSA with the Mosteller, DuBois, and Haycock formulas.

Check central body fat with a simple waist-to-height ratio.

Estimate how long it takes to reach your goal weight.

Calculate MAP and pulse pressure from blood pressure readings.

Calculate n! with digit count and trailing zeros.

Count arrangements and selections of r items from n.

Distance, slope, midpoint, and line equation from two points.

Reduce a ratio of two whole numbers to its simplest form.

Log of any number in any base, plus ln, log10, and log2.

Convert between square meters, acres, hectares, square feet, and more.

Convert liters, gallons, cups, ounces, cubic feet, and more.

Convert km/h, mph, m/s, knots, feet per second, and Mach.

Convert watts, kilowatts, horsepower, and BTU per hour.

Check if a year is a leap year and find the next one.

Find the weekday, day of year, and week number for any date.

Convert dog years to human years by size.