What day of the week was January 9, 2007?

January 9, 2007 was a Tuesday. You can work it out in your head with the Doomsday algorithm — this page shows the full step-by-step calculation.

January 9, 2007 was a
Tuesday

January 9, 2007 was a Tuesday — that’s 7,143 days ago. Below you can see exactly how to work the weekday out in your head with the Doomsday algorithm, along with a few other facts about the date.

Weekday

Tuesday

Day of year

9 of 365

ISO week

Week 2

Leap year?

Zodiac sign

Capricorn

Days ago

7,143

How to solve: January 9, 2007

1
Century anchor2000s→ Tuesday (2)
Practice →
2
Divide by 127 ÷ 12→ 0
Practice →
3
Remainder of 127 % 12→ 7
Practice →
4
Divide remainder by 47 ÷ 4→ 1
Practice →
5
Year's doomsday(2 + 0 + 7 + 1) % 7→ 3 → Wednesday
Practice →
6
Month doomsdayJanuary→ 3rd
Practice →
7
Distance9 − 3→ 6
Practice →
8
Final answer(3 + 6) % 7→ 2 → Tuesday

Now you try

Same month, one different day. You already know January 3 is a doomsday — count from there.

January 20, 2007

Do this for any date, without looking it up

The Doomsday algorithm is six short steps. Most people get to a reliable answer in under 30 seconds after an afternoon of practice.

Learn the algorithm Play today’s challenge

Did you know? Did you know that in Greek mythology, Tuesday is associated with the god Ares, the god of war?

January 9, 2007 was aTuesday

How to solve: January 9, 2007

Now you try

Do this for any date, without looking it up

January 9, 2007 was aTuesday

How to solve: January 9, 2007

Now you try

Do this for any date, without looking it up

January 9, 2007 was a
Tuesday

January 9, 2007 was a
Tuesday