Cutting & joints
Identical cuts from stock
- where
- usable length (mm)
- stock length (mm)
- total end trim loss (mm)
- pieces per stock
- finished piece length (mm)
- saw kerf (mm)
- stock lengths
- pieces required
Explain this equation
Works out how many identical pieces you can cut from each stock length, allowing for saw kerf and end trims, and how many stock lengths to buy.
Ls is the stock length and T the total lost to trimming both ends. Lu is what is left. l is the finished piece length, and k the width of material the blade removes. n is pieces per stock, q the pieces required and N the stock lengths needed. All lengths are in millimetres.
Each piece is treated as using l + k, one cut each. The ⌊ ⌋ brackets round down, because a part-piece is no use. Stock count rounds up with ⌈ ⌉, because you cannot buy part of a length. The calculator also shows the offcut left on each full length.
A 4800 mm length with 20 mm trimmed gives 4 × 1000 mm pieces with a 3 mm kerf, leaving 768 mm. 12 pieces need 3 lengths.
Watch out: it allows one kerf for every piece, so it is slightly cautious when the last piece would fit exactly.
Plan equal-length pieces with an explicit saw-cut count convention.
Enter your values to see the result.
Good to know
This calculator reserves one cut per piece, including the final separating cut. End trims are total length lost including their kerfs. It is conservative when an exact-fit end piece needs no separating cut.
Limits
The equal-piece stock tool reserves one separating kerf per piece and includes end-trim losses explicitly. It is not a mixed-length optimiser.
Sources
- Geometry / arithmetic
This is a calculation aid, not a structural design or compliance certificate. Every default is an example, not a specification for your project.