420 is a number you meet on social media, in dating profiles and every 20 April, and in cannabis culture it has one precise job: it stands for cannabis. The 420 meaning comes in two forms, a time (4:20 pm) and a date (20 April, which Americans write as 4/20), and the code is said “four twenty”. Unlike most of the stories told about it, its origin is well documented: five students in California, in 1971. We explain where 420 comes from, why 20 April became cannabis day, which explanations do not hold up and what is legal in Switzerland.
What does 420 mean?
420 is a code from cannabis culture that stands for cannabis and for sharing it with others. It is used in three ways: as a time (4:20 pm), as a date (20 April, written 4/20) and as a badge of the scene, as in “420-friendly”. The code word began in 1971 with five students in California.
So what does 420 mean when you see it today? The short 420 definition: one group’s password that became a symbol, not a police code and not a number with hidden significance. In everyday use the meaning of 420 shows in a few set phrases:
- “Is your house 420-friendly?” translates to “Can I smoke pot in here?”
- “It’s 420 somewhere!” refers to the clock: somewhere in the world it is 4:20 pm right now.
Both phrases show how a time of day turned into a word for the thing itself.
Four twenty: how 420 is pronounced
420 is pronounced four twenty, not “four hundred and twenty”. The way it is said gives away its American origin: the code was born in the US, where people read it as a time on the clock. Two spellings carry its two meanings: 4:20 is the time, and 4/20 is the date, because the US date format puts the month before the day. So if you wonder what is four twenty in a given sentence, the four twenty meaning depends on context, 4:20 pm or 20 April, and both lead back to the same story.
Where does 420 come from?
420 comes from five students at San Rafael High School in California who met at 4:20 pm in 1971. Of all the explanations in circulation, this origin of 420 is the only one backed by witnesses, as Olivia B. Waxman reconstructed it for TIME magazine, in “Here’s the Real Reason We Associate 420 With Weed”. The legends are sorted out in the myths section further down; here is the documented path, from a school wall to a worldwide date.
The Waldos and San Rafael High School
In 1971, five students at San Rafael High School in Marin County, California, arranged to meet after class at 4:20 pm by the statue of Louis Pasteur on the school grounds. They were Steve Capper, Dave Reddix, Jeffrey Noel, Larry Schwartz and Mark Gravich, and they called themselves the Waldos, after the wall they used to sit on. The meeting had a purpose: they had heard about an abandoned cannabis crop that a member of the US Coast Guard could no longer tend, and a treasure map was supposed to lead them to it.
Week after week the Waldos went looking, and week after week they came back empty-handed. They never found the crop, but the meeting time stuck: “420” became their code word, a way to talk about cannabis in front of parents and teachers without anyone catching on. This is also the truth behind the “secret island” legend: there was never an island full of cannabis, only five students and a crop they never found.
Grateful Dead and High Times: how 420 went global
Nobody set out to make 420 famous: it spread by chance, and then through one magazine. Dave Reddix’s brother got him work as a roadie for Phil Lesh, the bassist of the Grateful Dead, and the code word travelled into the band’s fan scene. The Deadheads followed the band from concert to concert and carried its counterculture slang with them.
On 28 December 1990, Deadheads in Oakland handed out flyers inviting people to meet on 20 April at 4:20 pm. One of them reached Steve Bloom, a reporter at the cannabis magazine High Times, which printed the flyer in 1991. From then on 420 was a global code rather than a local one, and in 1998 High Times credited the Waldos with coining it [1].
4/20 meaning: why 20 April is cannabis day
The 4/20 meaning is a date: in the US format, which writes the month before the day, 4/20 is 20 April. A fourth day of a twentieth month does not exist, so the Waldos’ meeting time was read as a day in the calendar instead. That is how a time on the clock became 420 day, the date the scene still calls weed day.
Since the 1990s, 20 April has been a day for the cannabis community worldwide, with meet-ups, concerts and rallies for legalisation. What people celebrate is the hemp plant and the culture around it, not a historical event. For many the day is also political, because cannabis laws differ widely from one country to the next. That Adolf Hitler was born on the same date is a coincidence; more on that in the myths section below.
It’s 420 somewhere: what does it mean?
“It’s 420 somewhere” is a saying from cannabis culture: because of time zones, it is always 4:20 pm somewhere in the world. People use it as a wink rather than a schedule, a way of saying the clock does not matter. The time itself comes from the Waldos, who met at 4:20 pm after school, and not from any idea that the hour is special. That is the whole meaning behind the phrase.
Why does 420 mean weed?
420 means weed because it began as a code word for THC cannabis, weed in the sense of marijuana. The Waldos used it for their meet-ups, and the scene still reads the number that way; why it is 420 and not another number comes down to nothing more than their meeting time. So the 420 weed connection is historical, a link between 420 and cannabis that travelled from the Deadheads to social media.
The weed of 420 is not the same thing as CBD flowers. Marijuana is the dried flowers of female cannabis plants rich in tetrahydrocannabinol (THC), the psychoactive compound in cannabis. Cannabidiol (CBD) is a different compound from the same plant, and CBD is not THC.
CBD flowers are hemp flowers with under 1% THC, and in Switzerland they are legal to buy, while THC-rich marijuana is not. Each variety has its own aroma, from earthy to citrus, and comes with a lab report showing its THC content. If you want to mark 420 here, what you will find in Swiss shops are legal CBD flowers grown in Switzerland.
420 in Switzerland: what is legal
420 is international, the law is not: in Switzerland, THC content separates legal from illegal. Hemp and CBD products with under 1% THC are legal, while THC cannabis remains banned under the Swiss Narcotics Act. For the detail, our guide explains why CBD is legal in Switzerland and on what conditions.
The one exception is the scientific pilot trials authorised by the Federal Office of Public Health (FOPH), in which some cities test the regulated sale of THC cannabis to registered participants. Do not confuse Switzerland with the US either: many English-language 420 explainers describe cannabis as legal, but that applies to certain US states, not to Swiss law. To see why the two cannabinoids are treated so differently, read our page on the difference between CBD and THC.
420 myths: what is not true
Next to the documented origin, four explanations keep coming back, and none of them holds up. From police radio to a telephone dialling code, we take them in the order you are most likely to hear them.
The police code myth
420 is not a police radio code for cannabis use; that is a myth. It has stuck around, probably because police codes such as “187” are familiar from rap lyrics. The only documented starting point is the Waldos in San Rafael: the number was a students’ code word, not a police one.
Hitler’s birthday on 20 April
The link between 420 and 20 April has nothing to do with Adolf Hitler, who was born on 20 April 1889: the overlap is pure coincidence. The date only attached itself to the code later, and only because the US date format reads 4/20 as 20 April.
Bob Dylan’s 12 × 35
The sum 12 × 35 = 420, taken from Bob Dylan’s song “Rainy Day Women #12 & 35”, is a reading made after the fact. The song, with its refrain “everybody must get stoned”, came out in 1966, while the code word was born in 1971. The numbers in the title do multiply to 420, but they explain nothing about where the code came from.
+420: the Czech dialling code
+420 is the international dialling code of the Czech Republic and has nothing to do with cannabis culture. If you are searching for “+420”, a Czech phone number has most likely called or messaged you. The match with the Waldos’ code word is pure chance, just like the date.
420 in everyday life: dating profiles, hashtags and greetings
Today you are more likely to meet 420 in profiles, posts and messages than on 20 April itself. The number has become a way of introducing yourself: using it says you belong to cannabis culture, or that you are open to it. Two places show this best, dating apps and social media.
What does 420 mean in a dating profile?
In a dating profile, “420-friendly” or “420 lover” means the person uses cannabis or is fine with a partner who does. The same goes for the question of what a 420 girl means: a woman who signals she is part of cannabis culture, nothing more. It is a lifestyle signal, not a code for something else, on a par with “non-smoker” or “wine lover” on apps such as Tinder. Some people use it as a filter, to find out early whether their lifestyles match. In Switzerland, THC cannabis is still banned, even when both profiles say 420-friendly.
#420 and ‘Happy 420’ on social media
#420 tags posts from cannabis culture, and “Happy 420” is the greeting for 20 April or for 4:20 pm. On Instagram and TikTok the hashtag gathers photos of plants, parties and rallies, so it works as a community label more than as information. Every 20 April, the number of these posts jumps.
Swiss shops post around 420 day too, usually about hemp products with under 1% THC. In Switzerland that is the legal version of the ritual, and it often takes the form of hemp flowers that come already rolled. Pre-rolled CBD joints made with Swiss hemp flowers are the most common example.
FAQ about 420
What is 710?
710 is a newer code from cannabis culture that stands for cannabis concentrates. Turned upside down, the number 710 spells the English word “OIL”. Following the model of 20 April, 10 July (7/10) has become the day for concentrates. Like 420, 710 is a cultural sign rather than a product name, and it is far less widespread than its older counterpart.
What does 420 mean in slang?
In slang, 420 stands for cannabis, and it works in three ways: as a word for cannabis itself, as an adjective in “420-friendly” and as a time of day, 4:20 pm. Whether you ask what 420 means in stoner slang or in a text message, the answer is the same: the code word the Waldos coined in 1971. Its three everyday uses are explained in the definition at the top of this article.
Key takeaways: 420 between cult code and Swiss law
420 is a code word with a documented origin. In 1971 the Waldos met at 4:20 pm, fans of the Grateful Dead and High Times magazine turned it into a worldwide term, and the US date format made four twenty into 20 April. The police code, Hitler and Bob Dylan belong to legend. In Switzerland the line is clear: only hemp with under 1% THC is legal. If you want to mark 20 April here, discover CBD flowers grown in Switzerland at uWeed.
