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Oct23 Fun Holiday – Mole Day

Mole Day is an unofficial holiday celebrated by chemists and chemistry students on October 23 in honor of the mole, a measuring unit in Chemistry.

A mole digging dirt.

A mole is a measuring unit in Chemistry and also a small animal found in North America, Europe, and Asia.


The mole measures chemical entities such as atoms or molecules and is formally defined as the amount of any substance that contains as many entities as there are atoms in 12 grams of carbon-12.

Associated with Avogadro’s number, a dimensionless measuring unit in Chemistry, the mole approximates to 6.02×1023. The number is named after Italian scientist Amedeo Avogadro.

6:02 a.m. to 6:02 p.m

Mole Day is celebrated annually between 6:02 a.m. to 6:02 p.m (18:02) on October 23 because when written in the month-date format, the date and time 6.02, 10/23 include the digits in Avogadro’s number.

The National Mole Day Foundation founded in 1991 celebrates the day every year with a theme. Some of the recent themes include Molar Eclipse in 2012, Mole of the Caribbean in 2010, and Molar Express in 2009.

How to Celebrate?

  • Get your geek on for this day. Wear a mole t-shirt and when someone asks you about it, explain the concept of mole to them.
  • Have a mole-themed party and serve guaca“mole” and wear mole (the animal) costumes.

Did You Know…

…that a group of moles is called a labor?

Mole Day Observances

Fun Holiday: Mole Day Observances
2024WedOct 23Mole Day
2025ThuOct 23Mole Day
2026FriOct 23Mole Day
2027SatOct 23Mole Day
2028MonOct 23Mole Day
2029TueOct 23Mole Day
2030WedOct 23Mole Day
2031ThuOct 23Mole Day
2032SatOct 23Mole Day
2033SunOct 23Mole Day

See all Fun Holidays

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