Tongue and Groove Siding Calculator
Estimate siding boards, courses, linear feet, opening deductions, gable area, trim allowance, and waste from exposed face coverage instead of nominal board width.
▦Siding presets
Load a common wall package, then fine-tune the exposure, openings, trim, and waste for your layout.
📏Wall and board inputs
Use the average run for repeated walls.
Horizontal mode reports course count from height.
Gable allowance
Enter 0 to calculate courses from exposure.
Board coverage
Visible face after the tongue seats in the groove.
Used only for the fastener estimate.
Openings
Corners, trim, and waste
Starter, frieze, window return, and cutoff allowance.
Siding estimate
Net siding area
-
sq ft
Boards to order
-
pieces
Total linear length
-
linear ft
Main wall courses
-
courses
Opening deduction
-
sq ft
Fastener estimate
-
nails/screws
▣Siding spec grid
📋Reference tables
| Board profile | Typical exposure | Coverage per 16 ft board | Common use |
|---|---|---|---|
| 1x4 tongue and groove | 3.25 to 3.5 in | 4.3 to 4.7 sq ft | Ceilings, small accents |
| 1x6 tongue and groove | 4.75 to 5.25 in | 6.3 to 7.0 sq ft | Exterior walls, cabins |
| 1x8 tongue and groove | 6.5 to 7.25 in | 8.7 to 9.7 sq ft | Gables, broad walls |
| 19 x 140 mm cladding | 130 to 135 mm | 2.1 to 2.2 sq m per 5 m | Metric wall cladding |
| Waste condition | Suggested waste | Why it changes | Calculator setting |
|---|---|---|---|
| Long rectangular wall | 5 to 8% | Few end cuts and simple courses | 5% or 8% |
| Mixed windows and doors | 10 to 12% | More cutouts and short returns | 10% or 12% |
| Steep gables | 12 to 15% | Angled offcuts are harder to reuse | 12% or 15% |
| Short random lengths | 20 to 30% | More joints and grading loss | 20% to 30% |
| Takeoff item | Formula used | Unit basis | Planning note |
|---|---|---|---|
| Rectangle walls | width x height x count | square area | Measure each wall face separately when widths differ. |
| Gable triangles | base x height x 0.5 x count | square area | Use the triangle above the eave line. |
| Openings | quantity x width x height | deducted area | Leave small openings in if trim consumes offcuts. |
| Trim allowance | linear trim / board length | extra boards | Adds pieces before final waste rounding. |
| Course check | What to compare | Best adjustment | Field to change |
|---|---|---|---|
| Top course too thin | height divided by exposure | Reduce exposure slightly across courses | Board exposure |
| Vertical layout has many joints | board length versus wall height | Use longer stock or plan a trim break | Board length |
| Many window cutouts | opening deduction versus gross area | Raise waste one step for sorting | Waste factor |
| Corner boards consume stock | corner height times count | Keep corner boards in the order | Corner count |
✦Practical notes
Exposure matters: Tongue and groove siding coverage is based on the exposed face after engagement, not the full manufactured width. Check one actual board before ordering.
Course planning: If the top course becomes very narrow, adjust exposure slightly or add a trim band so the wall finishes with a stronger reveal.
Always follow the siding maker's fastening, clearance, finish, and ventilation instructions. Support ladders and staging correctly, wear appropriate safety equipment, and confirm local exterior wall requirements before installation.
