Week numbers 166

166 has 52 ISO weeks. Week 1: Dec 30, 165 – Jan 5, 166 · Week 52: Dec 22 – 28

166 at a glance

Weeks in 16652
Week 1December 30, 165 – January 5, 166
Week 52December 22, 166 – December 28, 166
Days in 166365
Leap yearNo

All Weeks in 166

Week From To Month
Week 1 in 166 December 30, 165 January 5, 166 December / January
Week 2 in 166 January 6, 166 January 12, 166 January
Week 3 in 166 January 13, 166 January 19, 166 January
Week 4 in 166 January 20, 166 January 26, 166 January
Week 5 in 166 January 27, 166 February 2, 166 January / February
Week 6 in 166 February 3, 166 February 9, 166 February
Week 7 in 166 February 10, 166 February 16, 166 February
Week 8 in 166 February 17, 166 February 23, 166 February
Week 9 in 166 February 24, 166 March 2, 166 February / March
Week 10 in 166 March 3, 166 March 9, 166 March
Week 11 in 166 March 10, 166 March 16, 166 March
Week 12 in 166 March 17, 166 March 23, 166 March
Week 13 in 166 March 24, 166 March 30, 166 March
Week 14 in 166 March 31, 166 April 6, 166 March / April
Week 15 in 166 April 7, 166 April 13, 166 April
Week 16 in 166 April 14, 166 April 20, 166 April
Week 17 in 166 April 21, 166 April 27, 166 April
Week 18 in 166 April 28, 166 May 4, 166 April / May
Week 19 in 166 May 5, 166 May 11, 166 May
Week 20 in 166 May 12, 166 May 18, 166 May
Week 21 in 166 May 19, 166 May 25, 166 May
Week 22 in 166 May 26, 166 June 1, 166 May / June
Week 23 in 166 June 2, 166 June 8, 166 June
Week 24 in 166 June 9, 166 June 15, 166 June
Week 25 in 166 June 16, 166 June 22, 166 June
Week 26 in 166 June 23, 166 June 29, 166 June
Week 27 in 166 June 30, 166 July 6, 166 June / July
Week 28 in 166 July 7, 166 July 13, 166 July
Week 29 in 166 July 14, 166 July 20, 166 July
Week 30 in 166 July 21, 166 July 27, 166 July
Week 31 in 166 July 28, 166 August 3, 166 July / August
Week 32 in 166 August 4, 166 August 10, 166 August
Week 33 in 166 August 11, 166 August 17, 166 August
Week 34 in 166 August 18, 166 August 24, 166 August
Week 35 in 166 August 25, 166 August 31, 166 August
Week 36 in 166 September 1, 166 September 7, 166 September
Week 37 in 166 September 8, 166 September 14, 166 September
Week 38 in 166 September 15, 166 September 21, 166 September
Week 39 in 166 September 22, 166 September 28, 166 September
Week 40 in 166 September 29, 166 October 5, 166 September / October
Week 41 in 166 October 6, 166 October 12, 166 October
Week 42 in 166 October 13, 166 October 19, 166 October
Week 43 in 166 October 20, 166 October 26, 166 October
Week 44 in 166 October 27, 166 November 2, 166 October / November
Week 45 in 166 November 3, 166 November 9, 166 November
Week 46 in 166 November 10, 166 November 16, 166 November
Week 47 in 166 November 17, 166 November 23, 166 November
Week 48 in 166 November 24, 166 November 30, 166 November
Week 49 in 166 December 1, 166 December 7, 166 December
Week 50 in 166 December 8, 166 December 14, 166 December
Week 51 in 166 December 15, 166 December 21, 166 December
Week 52 in 166 December 22, 166 December 28, 166 December

Calendars 166

January 166
MoTuWeThFrSaSu
Week 112345
Week 26789101112
Week 313141516171819
Week 420212223242526
Week 52728293031
February 166
MoTuWeThFrSaSu
Week 512
Week 63456789
Week 710111213141516
Week 817181920212223
Week 92425262728
March 166
MoTuWeThFrSaSu
Week 912
Week 103456789
Week 1110111213141516
Week 1217181920212223
Week 1324252627282930
Week 1431
April 166
MoTuWeThFrSaSu
Week 14123456
Week 1578910111213
Week 1614151617181920
Week 1721222324252627
Week 18282930
May 166
MoTuWeThFrSaSu
Week 181234
Week 19567891011
Week 2012131415161718
Week 2119202122232425
Week 22262728293031
June 166
MoTuWeThFrSaSu
Week 221
Week 232345678
Week 249101112131415
Week 2516171819202122
Week 2623242526272829
Week 2730
July 166
MoTuWeThFrSaSu
Week 27123456
Week 2878910111213
Week 2914151617181920
Week 3021222324252627
Week 3128293031
August 166
MoTuWeThFrSaSu
Week 31123
Week 3245678910
Week 3311121314151617
Week 3418192021222324
Week 3525262728293031
September 166
MoTuWeThFrSaSu
Week 361234567
Week 37891011121314
Week 3815161718192021
Week 3922232425262728
Week 402930
October 166
MoTuWeThFrSaSu
Week 4012345
Week 416789101112
Week 4213141516171819
Week 4320212223242526
Week 442728293031
November 166
MoTuWeThFrSaSu
Week 4412
Week 453456789
Week 4610111213141516
Week 4717181920212223
Week 4824252627282930
December 166
MoTuWeThFrSaSu
Week 491234567
Week 50891011121314
Week 5115161718192021
Week 5222232425262728
Week 1293031

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Find the week number of a date

How week numbers are counted

Most of the world numbers weeks according to the ISO 8601 standard. A week starts on Monday, and week 1 is the week that contains the first Thursday of the year, which is always the week that contains 4 January.

Week 1 of 166 starts on December 30, 165 and ends on January 5, 166 (ISO 8601, Monday to Sunday). 166 has 52 ISO weeks.

Because of this rule, the first days of January can belong to the last week of the previous year, and the last days of December can belong to week 1 of the next year.

In the United States, weeks usually start on Sunday and week 1 is the week that contains 1 January, so the US week number can differ from the ISO week number.

Frequently Asked Questions (FAQ)

How many weeks does 166 have?

166 has 52 ISO weeks.

When does week 1 of 166 start?

Week 1 of 166 starts on December 30, 165 and ends on January 5, 166 (ISO 8601, Monday to Sunday).

When does the last week of 166 end?

Week 52 of 166 starts on December 22, 166 and ends on December 28, 166 (ISO 8601, Monday to Sunday).

Which years have 53 weeks?

The next years with 53 ISO weeks are 167, 172, 178, 184, 189.

Why do the US and Europe show different week numbers?

Europe follows ISO 8601: weeks start on Monday and week 1 is the week with the first Thursday of the year. In the US, weeks usually start on Sunday and week 1 is the week that contains 1 January, so the two numbers can differ by one.