# What size dowels to use for joints?

I'm comfortable with the process of creating and joining wood with dowels, but I'm not sure what size dowels to use in which cases? Specifically, I'm working with 1" thick stock (3/4" actual), what size should I use?

What are the other sizes and lengths of dowels used for?

Are there any recommended grouping or spacing for wood dowels?

When dealing with joinery I typically always deal with thirds. So I'd get whatever is closest to 1/3" that I can get. 3/8" is probably good for this, 5/16" even better. Thirds is a pretty good rule of thumb especially for furniture sized joinery.

This can be applied to all types of joinery such as mortise and tenon, splined miters, bridle joints, etc.

• +1 also. 1/3 is easier to remember, though with full-size lumber 3/8 is sometimes easier to compute and measure. :) Sep 26, 2011 at 17:34
• Sat in on a class of Roy Underhill's this weekend. His opinion is to use something at least 1/3rd of the thickness of the piece but less than half. Oct 3, 2011 at 19:09
• I don't see how this is the correct answer. If the actual thickness of the wood is 3/4" and the dowels should be 1/3 of this, shouldn't the dowels be 1/4"? A 5/16" dowel would be 1/16" too large, a 3/8" dowel would be 1/8" too large. Jun 1, 2020 at 20:02

The best work I know of on the topic was written by Tage Frid (see http://amazon.com).

The approximate rule-of-thumb, iirc, is to use a dowel no more than 3/8 the thickness of the wood to be joined (and not less than 1/4 the thickness).

### Expansion

For example, if you are joining 5/4 boards (finished thickness 1"), the dowels should be between 1/4" and 3/8" in diameter.

Likewise, if joining finished thickness 3/4" boards, use between 3/16" and 9/32" diameter dowels.

This presumes, of course, you're joining the boards on the narrow dimension (e.g. making a door frame).