Geohashing Day

From Geohashing

Template:Geohashing Day

This user earned the {{{year}}} Geohashing Day achievement
by celebrating in the ({{{latitude}}}, {{{longitude}}}) graticule on [[{{{coorddate}}} {{{latitude}}} {{{longitude}}}| May 21st {{{year}}}]].

If you celebrate this occasion on either Geohashing Day or the following Saturday you may display this ribbon on your user page. Yes, you may display both versions of the ribbon if you celebrate on both Geohashing Day and Mouse Over Day.

The Algorithm


The Algorithm as shown in xkcd comic #426, published on 21 May 2008.

The Algorithm that defines the sport of geohashing was first published on 21 May 2008. The anniversary of that date is therefore a special date for geohashers and deserving of special observances.

Date of Celebration

The official Geohashing Day is May 21st of each year, but for those who cannot geohash on weekdays, the following Saturday is designated Geohashing Day (observed), also known as Mouse Over Day. Both are appropriate days for celebrating.

Year Geohashing Day Mouse Over Day
2019 Tuesday May 25
2020 Thursday May 23
2021 Friday May 22
2022 Saturday -
2023 Sunday May 27
2024 Tuesday May 25
2025 Wednesday May 24
2026 Thursday May 23
2027 Friday May 22
2028 Sunday May 27
2029 Monday May 26
Danatar and his hashcot celebrating Mouseover Day 2010

Celebrating Geohashing Day

The best way to celebrate Geohashing Day is to geohash. On this date, make a special effort to have a unique adventure and to invite new people to join geohashing. Get out there and do something you wouldn't normally do. It doesn't matter if you make the coordinates, as long as you have an adventure!

Sample celebrations

After the first Geohashing Day has passed, you will be able to browse the Category:Geohashing Day achievement to see a list of expeditions claiming this achievement. Perhaps some of the more noteworthy will be linked here.


It is strongly preferred that you attempt to visit the coordinates generated for the actual date of your expedition. The current day's coordinates are always the first choice. There may be a geohasher in your graticule who does not use the wiki or peeron so has no way of knowing that you are going to an alternate location.

But, acknowledging that many graticules do not have even marginally accessible coordinates every day, and in order to expand the possibilities for adventure, Geohashing Day and Geohashing Day (observed) celebrations can include a retro hash to the coordinates for May 21st of any year since the announcement of the algorithm. Another possibility is to do both the actual geohash and one or more retrohashes. Perhaps you can find one near enough the days' coordinates to make that feasible.

Remember that for most awards other than the Geohashing Day ribbon you must reach the coordinates for that day. For example, you cannot claim Virgin Graticule, Consecutive geohash, Golf Geohash, Admit One Geohash or any other lucky location achievement if you are retrohashing.

Warning to those east of the Americas: - May 21st 2008 and earlier was before the 30W changeover.


Rhonda made this cake for Geohashing Day 2009

Cake is also highly recommended, especially if you succeed in transporting it to the geohash intact. Sharing cake with strangers at the geohash is a good way to tell people about geohashing. People willing to accept cake from strangers in party hats are probably the sort of people who would consider geohashing.

Annual Celebrations

Accounts of Geohashing Day events can be found in the appropriate daily categories.


Mouse Over Day will occasionally fall on Towel Day (May 25th). This happens every seven years, on average, and the next occurrence will be in 2024.

Note: The anti-node of 21 May (141st day of the year) is 20 November (324th day of the year, being 141+183.5 rounded up or 184 in a Leap Year).