4/20 Calculator
Calculate dates, times, and fun facts related to 4/20. Countdown to April 20th, convert 4:20 time, and explore cannabis culture.
Time Until Next 4/20
4/20 Quick Info
420 Fun Facts & History
Origins of 420
In the 1970s, a group of California high school students known as "The Waldos" used the term 4:20 as their meeting time to search for a hidden cannabis crop. The term spread and became synonymous with cannabis culture worldwide.
420 Statistics
- April 20th is celebrated globally
- 4:20 PM is the traditional time
- 420 is a code for cannabis in many contexts
- Several U.S. states have 420-friendly laws
420 Math Facts
- 420 = 2² × 3 × 5 × 7
- 420 is a Harshad number
- 420 is the sum of twin primes (419 + 421)
- 420°F is the vaporization point of THC
Frequently Asked Questions
What is 4/20?
4/20 (April 20th) is a counterculture holiday celebrating cannabis culture. The term also refers to 4:20 PM, a traditional time for cannabis consumption. It has evolved into a global phenomenon with events, music, and celebrations worldwide.
Where did 420 come from?
The term originated in 1971 with a group of students at San Rafael High School in California. They called themselves "The Waldos" and used "420" as code for meeting at 4:20 PM to search for an abandoned cannabis crop. The term spread through Grateful Dead concert flyers and became popular nationwide.
How is 4/20 celebrated?
4/20 is celebrated with gatherings, music festivals, cannabis consumption, advocacy events, and educational activities. Major celebrations occur in Denver, San Francisco, Vancouver, and Amsterdam. Many people also observe at home with friends.
Is 4/20 a legal holiday?
4/20 is not an official legal holiday, but it's widely recognized as a cultural holiday in many countries. Some cities have declared April 20th as an unofficial holiday for cannabis awareness and celebration.
Why is 420 significant mathematically?
420 has interesting mathematical properties: it's the product of prime numbers 2² × 3 × 5 × 7, it's divisible by 1, 2, 3, 4, 5, 6, 7, and it's the sum of twin primes (419 and 421).
How many days until 4/20?
Use our countdown calculator above to see exactly how many days, hours, and minutes until the next April 20th. The countdown updates in real-time based on your local time zone.