How to calculate shiplap
Shiplap boards overlap, so only the exposed face counts toward coverage. Measure the wall, subtract windows and doors, and divide by the face width; that gives the length of boards to buy, which you then divide into stock lengths.
| Exposed face | Linear feet | 8 ft boards | 16 ft boards |
|---|---|---|---|
| 3-1/2″ | 343 | 43 | 22 |
| 5-1/8″ | 234 | 30 | 15 |
| 5-1/2″ | 218 | 28 | 14 |
| 7-1/4″ | 166 | 21 | 11 |
Boards, joints and nails
- Stagger the end joints from row to row and land them on studs.
- The calculator counts two nails at each stud crossing at 16 in centres; follow the product's own fastening if it differs. Find studs with the stud calculator.
- For the lower wall only, the wainscoting calculator counts panels and cap rail; boards for floors or decks are on the linear feet calculator.
Common shiplap mistakes
- Using the full board width. The lap hides part of each board; use the face width.
- No waste allowance. Cuts around outlets and windows need about 10% more.
- Starting at the ceiling. Start at the floor or a level line so the last row is the one you rip.
Frequently asked questions
How much shiplap do I need for a wall?
Wall area × 12 ÷ exposed face width in inches, plus 10%. A 96 sq ft wall with a 5-1/8 in face needs about 247 linear feet.
How many shiplap boards for a 12 ft wall?
At 8 ft high with a 5-1/8 in face: 19 rows of 12 ft, or about sixteen 16 ft boards with waste.
Do you measure shiplap by the face or the full width?
By the exposed face. The lap overlaps the next board and does not add coverage.