# Why do circles have 400 gradians?
**URL:** https://boards.straightdope.com/t/why-do-circles-have-400-gradians/469
**Category:** Cecil's Columns/Staff Reports
**Created:** [January 21, 2000, 5:23pm UTC](https://boards.straightdope.com/t/why-do-circles-have-400-gradians/469 "2000-01-21T17:23:00Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)
#### Post date: [January 21, 2000, 5:23pm UTC](https://boards.straightdope.com/t/why-do-circles-have-400-gradians/469/1 "2000-01-21T17:23:00Z")
Why do so many calculators support gradians? For something I’ve never known anyone to use, it seems to be everywhere. Who uses these? Do they still use them, or have they caught up with the ancient Babylonians, and switched to degrees?
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_It is too clear, and so it is hard to see._
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### Author:  [@ZenBeam](https://boards.straightdope.com/u/ZenBeam)
#### Post date: [January 21, 2000, 5:25pm UTC](https://boards.straightdope.com/t/why-do-circles-have-400-gradians/469/2 "2000-01-21T17:25:00Z")
And the column is [http://www.straightdope.com/classics/a4\_194a.html](http://www.straightdope.com/classics/a4_194a.html)
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### Author:  [@woodja](https://boards.straightdope.com/u/woodja)
#### Post date: [January 21, 2000, 8:55pm UTC](https://boards.straightdope.com/t/why-do-circles-have-400-gradians/469/3 "2000-01-21T20:55:00Z")
Gradians are like degrees, but there are 400 in a circle, instead of 360. I imagine this is meant to make things easier in some situations, but radians seem better for most trig functions (to me).
Radians move from 0 to 2 \* PI, so there are about 6.283185307179586476925286766559 in a circle
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### Author:  [@woodja](https://boards.straightdope.com/u/woodja)
#### Post date: [January 21, 2000, 9:00pm UTC](https://boards.straightdope.com/t/why-do-circles-have-400-gradians/469/4 "2000-01-21T21:00:00Z")
oops
I guess I didn’t really read the subject line very well, or I wouldn’t have posted that. Sorry for the thoroughly useless response.
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### Author:  [@JonF](https://boards.straightdope.com/u/JonF)
#### Post date: [January 21, 2000, 9:44pm UTC](https://boards.straightdope.com/t/why-do-circles-have-400-gradians/469/5 "2000-01-21T21:44:00Z")
Surveyors use 'em. For some of their calculations it’s easier to have 100 grads in a right angle.
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jrf
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### Author:  [@Boris\_B](https://boards.straightdope.com/u/Boris_B)
#### Post date: [January 22, 2000, 12:10am UTC](https://boards.straightdope.com/t/why-do-circles-have-400-gradians/469/6 "2000-01-22T00:10:00Z")
It’s because the ancient Freedonians thought there were 400 days in a year.
Seriously, thought, I think it was an attempt at a metric measurement for angles. The right angle was taken as the “complete” unit, with 100 grads. There have also been attempts at metric time, if I remember correctly. Ten metric-hours in the day, 100 metri-minutes per hour, etc. It would sure make timesheets a lot easier, but it never really took off.
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Any similarity in the above text to an English word or phrase is purely coincidental.
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### Author:  [@Tom\_Dark](https://boards.straightdope.com/u/Tom_Dark)
#### Post date: [January 23, 2000, 7:06am UTC](https://boards.straightdope.com/t/why-do-circles-have-400-gradians/469/7 "2000-01-23T07:06:00Z")
Circles have 400 gradians because there were once 400 days in the year, as noted in the ancient corals living in the head of the contributor Nebuli. Or wait – no. Immanuel Velikovsky invented the 400 gradian circle after he realized the 360 degrees were merely a reflection of how many days there were in a year.
No. Wait. In ancient Blooplainia, the circle once had 365.2456978471 degrees, reflecting exactly the number of days in a year. But Blooplainian construction foremen found the damned thing impossibly complicated to work with, so they said “fuggit. It’s 400. The high priests will never notice. What’s the date, by the way?”
Milk and cookies for everybody, and lay this cheap imitation thread to rest. It hasn’t a prayer against “Up the Butt, Bob.”
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### Author:  [@Billdo](https://boards.straightdope.com/u/Billdo)
#### Post date: [January 25, 2000, 1:44am UTC](https://boards.straightdope.com/t/why-do-circles-have-400-gradians/469/8 "2000-01-25T01:44:00Z")
Gradians are an obscure method of measuring angles used in fields such as civil engineering and surveying. With gradians you have the advantage of having a right angle of 100 degrees, and angles can be therefore measured as a percentage of a right angle. Accordingly a 45 degree angle (pi/4 radians for the trig minded) is 50% of a right angle or 50 gradians.
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### Author:  [@CatInHat](https://boards.straightdope.com/u/CatInHat)
#### Post date: [January 25, 2000, 9:03pm UTC](https://boards.straightdope.com/t/why-do-circles-have-400-gradians/469/9 "2000-01-25T21:03:00Z")
IIRC, they were invented (or at least popularized) by the French, when they were trying to decimalize everything. This was sometime after the Revolution.
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Never attribute to malice anything that can be attributed to stupidity.
– Unknown