Question 1

What week is it right now?

Accepted Answer

Open /week-number — the date input is pre-filled to today, so the headline shows 'Week N of YYYY' for the current ISO week. The same panel also shows the weekday, the day-of-year, the quarter, and how many weeks remain in the ISO year.

Question 2

What is the difference between ISO year and calendar year?

Accepted Answer

ISO week 1 of a year is the week containing that year's first Thursday. So the last few days of December may sit in ISO week 1 of the next year (e.g. 2025-12-29 is ISO 2026-W01-1), and the first few days of January may sit in the last ISO week of the previous year. The tool always prints both.

Question 3

How many weeks are in 2026?

Accepted Answer

53 — because January 1 2026 falls on a Thursday. Most ISO years have 52 weeks; the 53-week years are those whose January 1 is Thursday, or leap years whose January 1 is Wednesday.

Consulta de número da semana ISO

O que são números de semana ISO

Ano ISO vs ano calendário

Dia do ano, trimestre, semanas restantes