Everyday Calculators

These everyday calculators answer the quick questions that come up at home, at work and at school: how old someone is to the day, how many days are left until a date, how many hours a shift lasted, what a sale price really is, and where a GPA stands after this term.

They’re grouped into three areas:

• Dates & Time: the age calculator gives exact age in years, months and days, with total days lived and a countdown to the next birthday. The date difference calculator counts the days between any two dates, in weeks, months and weekdays. The time duration calculator finds the hours and minutes between two clock times, including overnight shifts, and the time card calculator adds up a week of shifts with breaks and works out pay, with overtime at time and a half after 40 hours.
• Shopping: the discount calculator turns a percent off into a sale price, handles an extra coupon on top of a sale, and adds sales tax for the total at the register.
• School: the GPA calculator converts letter grades and credits into a GPA on the common 4.0 scale and combines it with a previous GPA to give a cumulative figure.

Each page explains the method behind the answer with a worked example, so you can check the numbers yourself. Date calculations use the Gregorian calendar and count every leap day. Time calculations use the 24-hour clock behind the scenes, so an end time earlier than the start time is read as the next day. Overtime follows the federal rule from the U.S. Department of Labor by default, and you can change the threshold and rate to match state or employer rules.

Everything runs in your browser. Nothing you enter, such as a date of birth or an hourly rate, is sent to a server or stored.