Everyday calculators
Calculate calendar age, date differences, clock durations and discounted prices with explicit counting and rounding conventions.
Updated
Dates, times and sale prices
Use the age calculator to count completed calendar years, months and days. Use the date calculator for elapsed calendar days or to add and subtract days. A clock-duration calculation is a different task: it compares hours and minutes and requires an explicit next-day choice for an overnight interval.
The discount calculator separates savings from the final price and applies sequential percentage reductions to the remaining amount. An optional entered tax rate applies after discounts; delivery and fixed coupons are outside that calculation.
Name the convention
A date range can mean elapsed days or a count including both endpoints. A sale can round each stage differently from an unrounded mathematical result. Check the explanation and state the convention when sharing an answer. These tools do not decide legal deadlines, verify identity or guarantee a retailer's checkout amount.
Turn an everyday question into clear inputs
For an event from Monday through Friday, ask whether you need four elapsed date-to-date steps or five included calendar dates. For a shift ending after midnight, select next day explicitly rather than relying on the clock reading to imply it. Calendar days and clock hours are different units, so a dated daylight-saving interval needs more information than these simple forms collect.
For a sale, identify the original price, the order of percentage reductions and any separately supplied tax rate. Twenty percent off followed by ten percent off leaves 72% of the original price, rather than 70%. Shipping and fixed coupons need separate treatment. The worked examples on each tool page show how to check these assumptions before trusting the final number.
Use the results for planning and arithmetic checks, then verify the applicable booking, merchant or organizational rules before acting. Dates and amounts can be invented when you are exploring a feature. There is no need to share an actual birthday or personal schedule to learn the method.