Week Calculator

Add or subtract weeks from a date, find the week number, calculate the start and end of a week, and convert weeks into days with this free week calculator.

Calculate Weeks

Week result = selected date plus or minus weeks and extra days. Week info shows week number, week start, week end, and day of year.
Your result will appear here.

How the week calculator works

Add weeks:
Choose add weeks to find a future date from your starting date.

Subtract weeks:
Choose subtract weeks to find a date before your starting date.

Get week info:
Choose week info to find the weekday, week number, start of week, and end of week.

Convert weeks:
Choose convert weeks to days to see the equivalent day count.

Why use a week calculator?

A week calculator is useful for deadlines, pregnancy tracking, school schedules, project timelines, fitness plans, billing cycles, events, appointments, work schedules, and planning dates a certain number of weeks away.

It helps quickly convert weeks into dates or days without manually counting through the calendar.

What your result means

Your result shows either the calculated date, total days, or week information depending on the calculation type selected. Results may include weekday, week number, week start date, week end date, and day of year.

Week calculator tips

Frequently asked questions

What is a week calculator?

A week calculator adds or subtracts weeks from a date, converts weeks to days, and shows week-related date details.

How many days are in a week?

There are 7 days in one week.

Can this calculator find the week number?

Yes. Choose get week info to see the ISO week number for the selected date.

Can I choose whether the week starts on Sunday or Monday?

Yes. Use the week starts on field to calculate the week start and week end dates based on your preferred calendar style.