WhatWeek

2026 Calendar with Week Numbers

View ISO week numbers, US-style comparison, week date ranges, and month calendars for 2026.

ISO weeks in 2026

53

2026 has 53 ISO weeks.

ISO Week 53 runs from Monday, December 28, 2026 to Sunday, January 3, 2027. It is the only Week 53 detail page included in the MVP, so use these links when planning or explaining the extra week.

Open Week 53 Why 53 weeks happen ISO week rules Compare US-style weeks

12-month calendar view

Scan the year by quarter, month, and ISO week before opening the full data table below.

Current ISO week in Asia/Singapore: 2026-W19, from 2026-05-04 to 2026-05-10.

Year atlas

2026 mapped across 53 ISO weeks

Scan the year by week, quarter, and month. The ribbon marks the current ISO week and makes the 53-week ISO year visible before you dive into each month.

ISO year length

53

Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9 Week 10 Week 11 Week 12 Week 13 Week 14 Week 15 Week 16 Week 17 Week 18 Week 19 Week 20 Week 21 Week 22 Week 23 Week 24 Week 25 Week 26 Week 27 Week 28 Week 29 Week 30 Week 31 Week 32 Week 33 Week 34 Week 35 Week 36 Week 37 Week 38 Week 39 Week 40 Week 41 Week 42 Week 43 Week 44 Week 45 Week 46 Week 47 Week 48 Week 49 Week 50 Week 51 Week 52 Week 53
W1 Quarter start W19 Current W53 Extra ISO week
W1 quarter start Current week W53 extra ISO week

Q1

W1-W14

Jan · Feb · Mar

Q2

W14-W27

Apr · May · Jun

Current week lives here

Q3

W27-W40

Jul · Aug · Sep

Q4

W40-W53

Oct · Nov · Dec

Includes Week 53

Quarter 1

Q1 planning view

W1-W14

Q1

January

Wk
Mon
Tue
Wed
Thu
Fri
Sat
Sun
1
2
3
4
5
6

Q1

February

Wk
Mon
Tue
Wed
Thu
Fri
Sat
Sun
5
6
7
8
9
10

Q1

March

Wk
Mon
Tue
Wed
Thu
Fri
Sat
Sun
9
10
11
12
13
14

Quarter 2

Q2 planning view

W14-W27

Q2

April

Wk
Mon
Tue
Wed
Thu
Fri
Sat
Sun
14
15
16
17
18
19

Q2

May

Current
Wk
Mon
Tue
Wed
Thu
Fri
Sat
Sun
18
19
20
21
22
23

Q2

June

Wk
Mon
Tue
Wed
Thu
Fri
Sat
Sun
23
24
25
26
27
28

Quarter 3

Q3 planning view

W27-W40

Q3

July

Wk
Mon
Tue
Wed
Thu
Fri
Sat
Sun
27
28
29
30
31
32

Q3

August

Wk
Mon
Tue
Wed
Thu
Fri
Sat
Sun
31
32
33
34
35
36

Q3

September

Wk
Mon
Tue
Wed
Thu
Fri
Sat
Sun
36
37
38
39
40
41

Quarter 4

Q4 planning view

W40-W53

Q4

October

Wk
Mon
Tue
Wed
Thu
Fri
Sat
Sun
40
41
42
43
44
45

Q4

November

Wk
Mon
Tue
Wed
Thu
Fri
Sat
Sun
44
45
46
47
48
49

Q4

December

Week 53
Wk
Mon
Tue
Wed
Thu
Fri
Sat
Sun
49
50
51
52
53
1

ISO vs US-style week comparison

ISO weeks start on Monday and Week 1 contains January 4. The simplified US-style week shown here starts on Sunday and Week 1 contains January 1, so the week number and date range can differ.

Date ISO week ISO range US-style week US-style range
2026-01-01 2026-W01 2025-12-29 to 2026-01-04 Week 1 2025-12-28 to 2026-01-03
2026-05-03 2026-W18 2026-04-27 to 2026-05-03 Week 19 2026-05-03 to 2026-05-09
2026-12-31 2026-W53 2026-12-28 to 2027-01-03 Week 53 2026-12-27 to 2027-01-02

ISO week table

Download CSV Previous year Next year

CSV columns: year, week, system, weekStarts, weekEnds, plus legacy weekday/weekend count fields. Open the CSV in Excel or Google Sheets to sort by week number, filter planning periods, or combine WhatWeek date ranges with your own spreadsheet data.

Week ISO notation Starts Ends Weekdays
Week 1 W01 2025-12-29 2026-01-04 5
Week 2 W02 2026-01-05 2026-01-11 5
Week 3 W03 2026-01-12 2026-01-18 5
Week 4 W04 2026-01-19 2026-01-25 5
Week 5 W05 2026-01-26 2026-02-01 5
Week 6 W06 2026-02-02 2026-02-08 5
Week 7 W07 2026-02-09 2026-02-15 5
Week 8 W08 2026-02-16 2026-02-22 5
Week 9 W09 2026-02-23 2026-03-01 5
Week 10 W10 2026-03-02 2026-03-08 5
Week 11 W11 2026-03-09 2026-03-15 5
Week 12 W12 2026-03-16 2026-03-22 5
Week 13 W13 2026-03-23 2026-03-29 5
Week 14 W14 2026-03-30 2026-04-05 5
Week 15 W15 2026-04-06 2026-04-12 5
Week 16 W16 2026-04-13 2026-04-19 5
Week 17 W17 2026-04-20 2026-04-26 5
Week 18 W18 2026-04-27 2026-05-03 5
Week 19 Current W19 2026-05-04 2026-05-10 5
Week 20 W20 2026-05-11 2026-05-17 5
Week 21 W21 2026-05-18 2026-05-24 5
Week 22 W22 2026-05-25 2026-05-31 5
Week 23 W23 2026-06-01 2026-06-07 5
Week 24 W24 2026-06-08 2026-06-14 5
Week 25 W25 2026-06-15 2026-06-21 5
Week 26 W26 2026-06-22 2026-06-28 5
Week 27 W27 2026-06-29 2026-07-05 5
Week 28 W28 2026-07-06 2026-07-12 5
Week 29 W29 2026-07-13 2026-07-19 5
Week 30 W30 2026-07-20 2026-07-26 5
Week 31 W31 2026-07-27 2026-08-02 5
Week 32 W32 2026-08-03 2026-08-09 5
Week 33 W33 2026-08-10 2026-08-16 5
Week 34 W34 2026-08-17 2026-08-23 5
Week 35 W35 2026-08-24 2026-08-30 5
Week 36 W36 2026-08-31 2026-09-06 5
Week 37 W37 2026-09-07 2026-09-13 5
Week 38 W38 2026-09-14 2026-09-20 5
Week 39 W39 2026-09-21 2026-09-27 5
Week 40 W40 2026-09-28 2026-10-04 5
Week 41 W41 2026-10-05 2026-10-11 5
Week 42 W42 2026-10-12 2026-10-18 5
Week 43 W43 2026-10-19 2026-10-25 5
Week 44 W44 2026-10-26 2026-11-01 5
Week 45 W45 2026-11-02 2026-11-08 5
Week 46 W46 2026-11-09 2026-11-15 5
Week 47 W47 2026-11-16 2026-11-22 5
Week 48 W48 2026-11-23 2026-11-29 5
Week 49 W49 2026-11-30 2026-12-06 5
Week 50 W50 2026-12-07 2026-12-13 5
Week 51 W51 2026-12-14 2026-12-20 5
Week 52 W52 2026-12-21 2026-12-27 5
Week 53 W53 2026-12-28 2027-01-03 5