What do 4/4, 5/4, 6/4, etc., mean?

The thickness of hardwood lumber is measured in quarters of an inch. So a 4/4 (four- quarters) would be 1″. This is the thickness before surfacing and the number you use to calculate board feet. This is also the thickness you pay for, even though, after planing, the thickness may be only 3/4″. The chart shows the typical thickness for hardwood lumber before and after planing. (What is softwood?)

Rough

Thickness

4/4 = 1″ 13/16″ 3/4″

5/4 = 1-1/4″ 1-1/16″ 1-13/32″

6/4 = 1-1/2″ 1-1/4″ 1-13/32″

8/4 = 2″ 1 3/4″ 1-1/2″

4/4 (four-quarter) lumber is 1″ thick when rough sawn. When 4/4 lumber is planed, it is typically finished at 13/16″ thick.

5/4 (five-quarter) lumberis 1.25″ thick when rough sawn. When 5/4 lumber is planed, typically it is finished at 1.063″ thick.

6/4 (six-quarter) lumber is 1.5″ thick when rough sawn. When 6/4 lumber is planed, typically it is finished at 1.25″ thick.

8/4 (eight-quarter) lumber is 2″ thick when rough sawn. When 8/4 lumber is planed, typically it is finished at 1.75″ thick.

12/4 (twelve-quarter) lumber is 3″ thick when rough sawn. When 12/4 lumber is planed, typically it is finished at 2.75″ thick.

16/4 (sixteen-quarter) lumber is 4″ thick when rough sawn. When 16/4 lumber is planed, typically it is finished at 3.75″ thick.

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Tools & Supplies

We’ve worked with everything we sell, and we only sell what works.

 

If you need it, KenCraft carries it.

We’re talking about well over 50 products for your projects, including some of the best- known names in woodworking supplies. And we maintain reliable inventory of the “small stuff” woodworkers depend on:

  • Biscuits
  • Butcher Block Oil
  • Buttons/Plugs/Flatheads
  • Carving Stock
  • CMT Saw Blades
  • Coat Hooks
  • Dowels
  • Drawer Slides
  • Euro Hinges
  • Kreg Tools
  • Mini Hinges for Jewelry Boxes
  • Pica Woodworkers Pencils
  • Picture Frame Hooks and Buttons
  • Push Sticks, Push Pads
  • Quick Joint Fastening System
  • Router Master Router Pad
  • Screws
  • Slip-it Tool Lubricant
  • Soft-close Euro Hinges
  • Spaceballs
  • T-slot Tracks
  • T-Track Router Table Accessories
  • Titebond Wood Glue
  • Toggle Clamps
  • Whiteside Router Bits
  • Wood Filler
  • Wood Tape

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