Carpentry Measurements
Precision measurement is the foundation of quality woodworking. Even a 1mm error can ruin a joint.
Essential Tools
- Tape measure — for general measurements (look for 1/32” or 1mm resolution)
- Combination square — for marking 90° and 45° angles
- Marking gauge — for consistent parallel lines
- Calipers — for measuring thickness and inside dimensions
Key Principles
- Measure twice, cut once — the oldest rule in carpentry
- Use the same tape — different tapes can vary slightly
- Mark with a knife — pencil lines are too thick for fine work
- Account for kerf — the saw blade removes material
Common Lumber Dimensions
| Nominal | Actual (inches) | Actual (cm) |
|---|---|---|
| 2×4 | 1.5 × 3.5 | 3.8 × 8.9 |
| 2×6 | 1.5 × 5.5 | 3.8 × 14.0 |
| 1×6 | 0.75 × 5.5 | 1.9 × 14.0 |
| 4×4 | 3.5 × 3.5 | 8.9 × 8.9 |