Calculators

Add or subtract a whole number of days or weeks from a Gregorian date and read the result date, the signed day count, and the weekday.

Add a tax rate you type onto a net price, or pull that same rate back out of a price that already includes tax. Results are rounded to cents.

Turn a cost and a selling price into margin and markup, or build a selling price from a cost plus one of those percents. The two percents use different denominators.

Find the future value of a principal plus an optional level contribution, using a nominal annual rate and a named compounding frequency.

Find the fixed monthly payment that pays off a principal at a nominal annual rate. The payment is rounded to cents before the total is added up.

Count exclusive days (nights between) and inclusive calendar days between two dates, plus a years/months/days span. Reversed dates stay positive.

Find the duration between two clock times. If the end is the same as or earlier than the start, the span crosses midnight (up to 24 hours).

Find the GCD and LCM of two integers. Decimals are rejected instead of silently truncated. Zero and negative inputs have stated rules.

Find X% of Y, what percent one number is of another, or the change between two values. The calculation stays in this browser.

Calculate the percentage change from an original value to a new value, with a clear increase, decrease, or unchanged label.

Enter an original price and a discount percent to see the amount taken off and the price you pay. Tax is not added.

Calculate the arithmetic mean of a list. Invalid tokens are reported instead of silently dropped. Count, sum, and average are shown.

Simplify A : B, or find the missing X in A : B = C : X. Zeros and invalid values are handled in the status line.

Add, subtract, multiply, or divide two fractions. The primary result is an exact fraction, then a simplified form and a decimal view.

Calculate age in years, months, and days from a date of birth to today or another date. Uses calendar months, not 365-day years.