Àwọn
Wá àwọn àwọn ìṣàmúlò-ètò ISO tí a bá fi pamọ́ fún àwọn ààyè-iṣẹ́ àwọn ìṣàmúlò-ètò.
Àwọn Àtòjọ-ẹ̀yàn àwọn ìṣàmúlò-ètò
Àkóónú ìṣàmúlò-ètò yìí
A week number calculator returns the ISO 8601 week number for a date — the standard used across business, logistics and Europe, where weeks run Monday to Sunday and week 1 is the week containing the first Thursday of the year. It also gives the ISO week-numbering year, the calendar quarter, the day-of-year number and how many weeks are left in the year.
Under the ISO rule a year has 52 or 53 weeks, each running Monday to Sunday, and week 1 is defined as the week that holds the year’s first Thursday (equivalently, the week containing 4 January). This is why a date in the first days of January can still belong to the last week of the previous year, and a late-December date can already sit in week 1 of the next year — the tool reports the ISO week-numbering year separately so that mismatch is clear.
For example, 1 January 2026 falls in ISO week 1 of 2026, but 1 January 2023 (a Sunday) sits in ISO week 52 of 2022. Manufacturing, shipping, publishing and European payroll systems schedule by these "CW" or "KW" week numbers, so this is the tool for answering "what week number is it", planning a delivery for "week 34", or checking which quarter a date belongs to.
Àwọn Àtòjọ-ẹ̀yàn
Bawo ní a ṣè ṣàfihàn àwọn àwọn ìṣàmúlò-ètò ISO?
Under ISO 8601 weeks start on Monday and week 1 is the week that contains the first Thursday of the year — equivalently, the week containing 4 January. This is why early-January and late-December dates can belong to a neighbouring year.
Kini idi ti o fi lè yatọ̀ nígbà kan láti inú ọdun ISO sí ọdun kalẹnda?
Dates in the first days of January can fall in the last ISO week of the previous year, and late-December dates can fall in week 1 of the next year. The ISO week-numbering year reflects which year the week belongs to.
Ìgbà wò nínú àwọn ààtò àwọn ààtò àwọn ààtò àwọn ààtò àwọn ààtò àwọn ààtò àwọn ààtò àwọn ààtò àwọn ààtò àwọn ààtò
Oṣu mẹfa ni oṣu kalẹnda ti ọjọ ti o wọpọ: Q1 jẹ Oṣu kejila-Oṣù Kẹrin, Q2 jẹ Oṣu Kẹrin-Oṣù Kẹrin, Q3 jẹ Oṣu Kẹrin-Oṣù Kẹrin ati Q4 jẹ Oṣu Kẹrin-Oṣù Kẹrin.
Ìgbà wò nínú odun nínú àwọn àkókò?
Under ISO 8601 a year has 52 weeks in most years and 53 in a handful (when 1 January or the leap-year 31 December falls on a Thursday). The tool tells you how many ISO weeks remain in the current year.
Àwọn ìyatọ̀ wò nínú àwọn à
ISO weeks start on Monday with week 1 holding the first Thursday. The common US convention starts weeks on Sunday and calls the week of 1 January week 1. This calculator uses the ISO standard, so numbers can differ by one from a US calendar.
Kini o tumọ si CW tabi KW nínú kalẹ́nìtó?
CW (calendar week) and the German KW (Kalenderwoche) are just labels for the ISO week number — CW 34 is ISO week 34. Enter any date in that week to confirm which CW/KW it belongs to.
API — ló àwọn ìṣàmúlò-ètò yìí láti inú ìṣàmúlò-ètò
Fi àwọn ìṣàmúlò-ètò yìí kọ̀ǹpútà yìí láti jẹ́ ààyè-iṣẹ́ JSON tí a tí fi pamọ́ - kò ní bọ́tìnì kan tí a fẹ́. Fi àwọn fálù ààyè-iṣẹ́ sílẹ̀ sí bí àwọn àwọn ìṣàmúlò-ètò àti JSON. Anything you omit uses the same default this page is pre-filled with; an unknown parameter is a 400, never a silent zero. Ka àwọn àkọlé API kíkún →
Àwọn Ààyè Ìjánu-ìṣàmúlò-ètò
GET https://calculator.free/api/v1/week-number/curl
curl "https://calculator.free/api/v1/week-number/?date=2026-09-08"JavaScript fetch()
const r = await fetch(
"https://calculator.free/api/v1/week-number/?" + new URLSearchParams({
"date": "2026-09-08"
}));
const data = await r.json();
console.log(data.results);Results are estimates for general guidance only, not financial, medical or tax advice.