# Octagon Help



## asrubin (Jan 1, 2008)

I would like to make an octagon picture frame that is 24" across from each midpoint. I know that the angles must be cut at 22.5% on each side. What is the formula for the length of each board? Thanks for any and all help


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## Mikemorgan (Dec 7, 2009)

*Re: Octagon*

The formula is: x = 0.4142w, where w is the width of the octagon and x is the length of each side. 

I can't post the web page because of my newby status so Google "perimeter of an octagon" and look for: "mathcentral.uregina.ca/QQ/database" for the derivation and an illustration.
Hope this helps.


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## Gene Howe (Jul 10, 2007)

I'm a real math dummy so, what I do is draw a circle that will encompass the octagon, set my points around the circle, draw the lines from point to point and measure the lines. 
This gets me close enough for woodwork.


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## bobj3 (Jan 17, 2006)

Area and Perimeter of a Regular Octagon
The perimeter of an octagon
Octagon Perimeter and Surface Area Formulas
Ocatgon

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## asrubin (Jan 1, 2008)

Thanks to all.......I guess I will just make a square....that's easy......


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## BigJimAK (Mar 13, 2009)

You can if you wish, Alan... or you can give the (accurate) equation Mike gave you. Make each section 0.4142 times the overall width and you'll get what you've asked for.


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## waynoe (Sep 29, 2004)

Alan
I'm with Gene on this. All you need is a compass, a protractor and a sharp pencil. If possible make a full size drawing and use it as a template. (the kiss method)
Don't give up, it's not that difficult which ever method you use is right.
Wayne


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## BigJimAK (Mar 13, 2009)

Drawing out a template is probably best if you need the hex size "Dead-nuts", but I've created a table of mighty close sizes. The "width" column is the distance between the flat opposite sides of the hexagon and the "leg" is the length of each piece.

I hope this helps someone.

Width Leg
==========
8" 3-5/16"
8-1/2"	3-1/2"
9" 3-3/4"
9-1/2"	3-15/16"
10" 4-1/2"
10-1/2"	4-3/8"
11" 4-9/16"
11-1/2"	4-3/4"
12" 4-31/32"
12-1/2"	5-3/16"
13" 5-3/8"
13-1/2"	5-19/32"
14" 5-13/16"
14-1/2"	6"
15" 6-3/16"
15-1/2"	6-7/16"
16" 6-5/8"
16-1/2"	6-13/16"
17" 7-1/16"
17-1/2"	7-1/4"
18" 7-7/16"
18-1/2"	7-11/16"
19" 7-7/8"
19-1/2"	8-1/16"
20' 8-1/4"
20-1/2"	8-1/2"
21" 8-11/16"
21-1/2"	8-7/8"
22" 9-1/8"
22-1/2"	9-5/16"
23" 9-1/2"
23-1/2"	9-3/4"
24" 9-15/16"


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## AxlMyk (Jun 13, 2006)

Octagon Layout Calculator


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## Knothead47 (Feb 10, 2010)

I just ask my son and daughter-in-law: engineer and math teacher, respectively.


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## Montanamike60 (Apr 5, 2015)

Great link thanks!


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