National Mole Day 2026
National Mole Day is an unofficial chemistry observance marked on October 23, traditionally from 6:02 a.m. to 6:02 p.m. so the stamp reads 6:02 10/23 — a pun on Avogadro’s number (about 6.02×10²³). In 2026 it falls on Friday, October 23. It is not Mexican mole sauce, not guacamole, and not a federal holiday. Maurice Oehler and the National Mole Day Foundation launched it in 1991.
About National Mole Day
National Mole Day is an unofficial chemistry observance marked on October 23, traditionally from 6:02 a.m. to 6:02 p.m. so the date-time stamp reads 6:02 10/23 — a pun on Avogadro’s number (about 6.02×10²³ particles per mole). In 2026 it falls on Friday, October 23. It is not a food day, not Mexican mole sauce, and not National Guacamole Day. It is not a federal holiday. Classroom and chemistry-club custom — do not cook mole poblano for this page.
Chemistry mole vs Mexican mole (and same-date neighbors)
| Name | Typical date | What it is |
|---|---|---|
| National Mole Day | October 23 (6:02 a.m.–6:02 p.m.) | This page — SI mole / Avogadro pun |
| Mexican mole sauce / mole poblano | Food (any date) | Different “mole” — never treat this page as a recipe |
| National Guacamole Day | September 16 on this site | Food — not this mole |
| National Boston Cream Pie Day | Also October 23 | Same date; dessert |
| National Horror Movie Day | Also October 23 | Same date; film |
This mole is chemistry. National Guacamole Day appears here only as “not this mole” disambiguation — a different word and a different date. Same-date neighbors National Boston Cream Pie Day and National Horror Movie Day share October 23 only as a calendar stack. National Chemistry Week (ACS, mid-to-late October) is a related program, not the same day. For everything sharing October 23, see the October 23 hub. Month hub: October national days.
A short, defendable timeline
The chemistry joke. A mole (mol) is the SI unit for amount of substance. Classroom day language still uses the rounded 6.02×10²³ figure so the clock-and-date stamp 6:02 10/23 works. Since the 20 May 2019 SI revision, the Avogadro constant is exact at 6.02214076×10²³ mol⁻¹ — useful for advanced classes; the day’s pun still leans on the rounded form. Amedeo Avogadro himself did not set the modern constant.
U.S. calendar day. The idea seed is often credited to Margaret Christoph’s article in The Science Teacher. Maurice Oehler and the National Mole Day Foundation launched the observance on 15 May 1991 in Prairie du Chien, Wisconsin (nonprofit framing follows in 1992). Yearly themes appear in classroom kits and club events. This page does not speak as the official foundation, claim federal-holiday status, or treat Mexican mole sauce or National Guacamole Day as the same observance.
How to celebrate National Mole Day
- Mark 6:02 with a short demo or non-alcoholic toast so the stamp reads 6:02 10/23.
- Explain what a mole weighs for a simple substance (water, table salt, or sugar) using lab or kitchen scales.
- Check the year’s NMDF theme if you are running a club event, then build one activity around it.
- Wear the animal-mole hat pun if you like — then do the math so the joke earns its keep.
- Do not cook mole poblano for this page — food “mole” is a different word and a different topic.
Answer-ready summary
National Mole Day is an unofficial chemistry observance marked on October 23, traditionally from 6:02 a.m. to 6:02 p.m. so the stamp reads 6:02 10/23 — a pun on Avogadro’s number (about 6.02×10²³). In 2026 it falls on Friday, October 23. It is not Mexican mole sauce, not guacamole, and not a federal holiday. Maurice Oehler and the National Mole Day Foundation launched it in 1991.
Facts
- Observed 6:02 a.m. to 6:02 p.m. on October 23 (6:02 10/23)
- Maurice Oehler founded the National Mole Day Foundation on 15 May 1991 in Prairie du Chien, Wisconsin
- The Avogadro constant has been defined as exactly 6.02214076×10²³ mol⁻¹ since 20 May 2019
- It is not Mexican mole sauce, not the animal (except as a classroom pun), and not guacamole
- The day is unofficial; it is not a U.S. federal holiday
Upcoming dates
- Friday, October 23, 2026
- Saturday, October 23, 2027
- Monday, October 23, 2028
- Tuesday, October 23, 2029
- Wednesday, October 23, 2030
Frequently asked questions
When is National Mole Day in 2026?
Friday, October 23, 2026, traditionally 6:02 a.m. to 6:02 p.m.
Is today National Mole Day?
No. National Mole Day in 2026 falls on Friday, October 23, 2026, not today.
Is this about Mexican mole sauce?
No. This page is the chemistry mole (Avogadro’s number / SI unit). Mexican mole sauce and guacamole are different topics — keep them on their own pages.
Who started National Mole Day?
Maurice Oehler and the National Mole Day Foundation (1991), with earlier classroom inspiration often linked to Margaret Christoph’s Science Teacher article.
What is a mole in chemistry?
The SI unit for amount of substance. Classroom day language uses about 6.02×10²³ particles per mole; the exact Avogadro constant since 2019 is 6.02214076×10²³ mol⁻¹.
How do you celebrate?
Run a 6:02 classroom demo, weigh a simple mole of a substance, follow the year’s theme, and keep the day on chemistry — not sauce.
Is it a federal holiday?
No.
Share
Help others discover this day by sharing it.