Week numbers 171

171 has 52 ISO weeks. Week 1: Dec 31, 170 – Jan 6, 171 · Week 52: Dec 23 – 29

171 at a glance

Weeks in 17152
Week 1December 31, 170 – January 6, 171
Week 52December 23, 171 – December 29, 171
Days in 171365
Leap yearNo

All Weeks in 171

Week From To Month
Week 1 in 171 December 31, 170 January 6, 171 December / January
Week 2 in 171 January 7, 171 January 13, 171 January
Week 3 in 171 January 14, 171 January 20, 171 January
Week 4 in 171 January 21, 171 January 27, 171 January
Week 5 in 171 January 28, 171 February 3, 171 January / February
Week 6 in 171 February 4, 171 February 10, 171 February
Week 7 in 171 February 11, 171 February 17, 171 February
Week 8 in 171 February 18, 171 February 24, 171 February
Week 9 in 171 February 25, 171 March 3, 171 February / March
Week 10 in 171 March 4, 171 March 10, 171 March
Week 11 in 171 March 11, 171 March 17, 171 March
Week 12 in 171 March 18, 171 March 24, 171 March
Week 13 in 171 March 25, 171 March 31, 171 March
Week 14 in 171 April 1, 171 April 7, 171 April
Week 15 in 171 April 8, 171 April 14, 171 April
Week 16 in 171 April 15, 171 April 21, 171 April
Week 17 in 171 April 22, 171 April 28, 171 April
Week 18 in 171 April 29, 171 May 5, 171 April / May
Week 19 in 171 May 6, 171 May 12, 171 May
Week 20 in 171 May 13, 171 May 19, 171 May
Week 21 in 171 May 20, 171 May 26, 171 May
Week 22 in 171 May 27, 171 June 2, 171 May / June
Week 23 in 171 June 3, 171 June 9, 171 June
Week 24 in 171 June 10, 171 June 16, 171 June
Week 25 in 171 June 17, 171 June 23, 171 June
Week 26 in 171 June 24, 171 June 30, 171 June
Week 27 in 171 July 1, 171 July 7, 171 July
Week 28 in 171 July 8, 171 July 14, 171 July
Week 29 in 171 July 15, 171 July 21, 171 July
Week 30 in 171 July 22, 171 July 28, 171 July
Week 31 in 171 July 29, 171 August 4, 171 July / August
Week 32 in 171 August 5, 171 August 11, 171 August
Week 33 in 171 August 12, 171 August 18, 171 August
Week 34 in 171 August 19, 171 August 25, 171 August
Week 35 in 171 August 26, 171 September 1, 171 August / September
Week 36 in 171 September 2, 171 September 8, 171 September
Week 37 in 171 September 9, 171 September 15, 171 September
Week 38 in 171 September 16, 171 September 22, 171 September
Week 39 in 171 September 23, 171 September 29, 171 September
Week 40 in 171 September 30, 171 October 6, 171 September / October
Week 41 in 171 October 7, 171 October 13, 171 October
Week 42 in 171 October 14, 171 October 20, 171 October
Week 43 in 171 October 21, 171 October 27, 171 October
Week 44 in 171 October 28, 171 November 3, 171 October / November
Week 45 in 171 November 4, 171 November 10, 171 November
Week 46 in 171 November 11, 171 November 17, 171 November
Week 47 in 171 November 18, 171 November 24, 171 November
Week 48 in 171 November 25, 171 December 1, 171 November / December
Week 49 in 171 December 2, 171 December 8, 171 December
Week 50 in 171 December 9, 171 December 15, 171 December
Week 51 in 171 December 16, 171 December 22, 171 December
Week 52 in 171 December 23, 171 December 29, 171 December

Calendars 171

January 171
MoTuWeThFrSaSu
Week 1123456
Week 278910111213
Week 314151617181920
Week 421222324252627
Week 528293031
February 171
MoTuWeThFrSaSu
Week 5123
Week 645678910
Week 711121314151617
Week 818192021222324
Week 925262728
March 171
MoTuWeThFrSaSu
Week 9123
Week 1045678910
Week 1111121314151617
Week 1218192021222324
Week 1325262728293031
April 171
MoTuWeThFrSaSu
Week 141234567
Week 15891011121314
Week 1615161718192021
Week 1722232425262728
Week 182930
May 171
MoTuWeThFrSaSu
Week 1812345
Week 196789101112
Week 2013141516171819
Week 2120212223242526
Week 222728293031
June 171
MoTuWeThFrSaSu
Week 2212
Week 233456789
Week 2410111213141516
Week 2517181920212223
Week 2624252627282930
July 171
MoTuWeThFrSaSu
Week 271234567
Week 28891011121314
Week 2915161718192021
Week 3022232425262728
Week 31293031
August 171
MoTuWeThFrSaSu
Week 311234
Week 32567891011
Week 3312131415161718
Week 3419202122232425
Week 35262728293031
September 171
MoTuWeThFrSaSu
Week 351
Week 362345678
Week 379101112131415
Week 3816171819202122
Week 3923242526272829
Week 4030
October 171
MoTuWeThFrSaSu
Week 40123456
Week 4178910111213
Week 4214151617181920
Week 4321222324252627
Week 4428293031
November 171
MoTuWeThFrSaSu
Week 44123
Week 4545678910
Week 4611121314151617
Week 4718192021222324
Week 48252627282930
December 171
MoTuWeThFrSaSu
Week 21
Week 492345678
Week 509101112131415
Week 5116171819202122
Week 5223242526272829
Week 13031

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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 171 starts on December 31, 170 and ends on January 6, 171 (ISO 8601, Monday to Sunday). 171 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 171 have?

171 has 52 ISO weeks.

When does week 1 of 171 start?

Week 1 of 171 starts on December 31, 170 and ends on January 6, 171 (ISO 8601, Monday to Sunday).

When does the last week of 171 end?

Week 52 of 171 starts on December 23, 171 and ends on December 29, 171 (ISO 8601, Monday to Sunday).

Which years have 53 weeks?

The next years with 53 ISO weeks are 172, 178, 184, 189, 195.

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.