Sheet metal
Frame cut list calculator
In short
A rectangular L × H frame in a section of width p is cut according to the corner joints: with 45° mitres, rails l = L and uprights h = H, point to point; with through uprights, l = L − 2p; with through rails, h = H − 2p. The squareness diagonal is D = √(L² + H²).
Calculation
Example calculated with the tool’s default values.
Inputs
- Overall width
- 1200 mm
- Overall height
- 800 mm
- Number of frames
- 1
- Section width (in the frame plane)
- 40 mm
- Section depth (frame thickness)
- 40 mm
- Corner joints
- 45° mitre
- Saw kerf
- 2 mm
Results
- Rail (point to point)
- 1200.0 mm× 2
- Upright (point to point)
- 800.0 mm× 2
- Outside diagonal (squareness)
- 1442.2 mm
Worked example
Every value in this section belongs to the example, calculated with the tool’s default values.
Other results of the example
- Inside diagonal
- 1331.5 mm
- Total section length
- 4000 mm4008 mm with one kerf per piece
- Mitre: lengths are long point to long point (outside); cut head-to-tail to share the 45° cuts.
- Squareness: both diagonals must be equal before tacking the opposite corners.
- Allow for weld shrinkage at the corners (Shrinkage tool) on welded frames.
Step-by-step calculation
Rails
l = L
1200.0 mm × 2
Uprights
h = H
800.0 mm × 2
Diagonal
D = √(L² + H²)
√(1200² + 800²) = 1442.2 mm
Total
Σ = n × (w + h); + kerf per piece
4000 mm ; 4008 mm
Cut list
| Part | Length (mm) | Qty | Cuts |
|---|---|---|---|
| Traverse | 1200.0 | 2 | 45° / 45° |
| Montant | 800.0 | 2 | 45° / 45° |
How to use it
- Enter the overall width and height of the frame.
- Enter the section width in the frame plane and its depth.
- Pick the corner joints: 45° mitre, through uprights or through rails.
- Enter the saw kerf and the number of frames.
- Read the cut length of the rails.
Frequently asked questions
How do I work out the cut list of a steel frame?
It depends on the corner joints. With 45° mitres, the rails are l = L and the uprights h = H, long point to long point on the outside. With through uprights, the rails fit between them: l = L − 2p. With through rails: h = H − 2p. Each frame has 2 rails and 2 uprights.
How do I check that a frame is square?
Measure both diagonals: they must be equal before tacking the opposite corners. The outside diagonal is D = √(L² + H²): for a 1200 × 800 mm frame, √(1200² + 800²) = 1442.2 mm. The calculation also gives the inside diagonal, between the inner corners of the frame.
What total section length does a frame need?
Σ = n × (l + h), plus one saw kerf per piece. Example: 1200 × 800 mm mitred frame in a 40 mm section: 2 rails of 1200.0 mm and 2 uprights of 800.0 mm, so 4000 mm, and 4008 mm with a 2 mm kerf per piece. For mitres, cut head-to-tail to share the 45° cuts.
Limits
Indicative results: geometry only. For mitres, lengths are long point to long point on the outside. The section must stay narrow relative to the frame (2 × p below the shortest side). On a welded frame, allow for weld shrinkage at the corners.
Sources
- Géométrie : Cadre rectangulaire ; diagonale D = √(L² + H²)