Week Number Calculator: What Week Is It?
Pick a date, or leave it empty to see today.
Choose a date, or leave it empty for today.
Week numbers explained
The calculator uses ISO week numbers, which are the standard in the UK and Europe. Weeks start on Monday, and week 1 is the week with the first Thursday of the year. This means the first days of January can belong to the last week of the previous year, and a year has 52 or 53 weeks.
UK tax weeks and months
The tax year starts on 6 April, so tax week 1 begins on 6 April and tax month 1 runs from 6 April to 5 May. These are the numbers on payslips and in PAYE. See the tax dates and deadlines for the year.
Frequently asked questions
What week number is it today?
Leave the date empty and the calculator shows the ISO week number for today, using your device date.
How many weeks are in a year?
A year has 52 or 53 ISO weeks. 53-week years happen about every five or six years.
What is a tax week?
A numbered week of the tax year that starts on 6 April. It is used on payslips for weekly paid workers.
More from UK Answers
Figures are for the 2026/27 tax year from official sources and are estimates for guidance only, not financial or legal advice. Printed from ukanswers.co.uk.