Siding coverage-per-square reference
Convert an area into squares, boxes or bundles: pick a material, enter your area and waste, and the tool returns whole units by the material’s coverage. 1 square is always 100 sq ft.
1,470 sq ft of Vinyl lap (double-4") is about 8 boxs. Convert your area into squares, boxes or bundles with the material’s coverage; 1 square is always 100 sq ft, but the box/bundle coverage and exposure are the manufacturer’s numbers — confirm them.
1 Enter your numbers
Siding is sold in different units depending on the material — vinyl by the box, cedar by the bundle, fiber cement and wood lap often by the square — but the arithmetic is one identity. Take your area, add a waste factor, divide by the coverage of one unit, and round up to whole units. The only constant that never changes is the square: 1 square = 100 sq ft, always. The box and bundle coverage are the manufacturer’s numbers and vary with exposure, which is why this tool reads them from the same signature coverage dataset that drives the quantity calculators.
This reference is the bridge between an area and an order. Feed it the net area from the how-to-measure tool and a waste factor from the waste-factor calculator, and it returns the whole squares, boxes or bundles to buy. For the same math specialized to material boxes, use the boxes-by-material calculator; to see the exposure behind each coverage number, see the exposure reference.
Formula
Whole units to buy:
units = ceil( area × (1 + waste) ÷ coverage_per_unit )
where coverage_per_unit is the material’s labeled coverage — e.g. ~200 sq ft per box of double-4″ vinyl, ~25 sq ft per bundle of cedar shingle, or 100 sq ft per square for lap sold by the square. The ceil() is deliberate: you cannot buy a partial box, and rounding up leaves the small cushion you want for cuts and mistakes. The + waste is on top of that, sized to the layout.
Worked example
Take 1,336 sq ft of net area at a 10% waste factor. With waste that is 1,336 × 1.10 = 1,469.6 sq ft. In double-4″ vinyl at 200 sq ft per box, that is ceil(1,469.6 ÷ 200) = ceil(7.35) = 8 boxes (16 squares of coverage). In cedar shingle at 25 sq ft per bundle, the same 575 sq ft of a smaller job would be ceil(575 ÷ 25) = 23 bundles. One identity, two materials, whole units either way.
From area to a whole-unit order
Order in whole units and keep a little in reserve. Points to remember: the square is fixed at 100 sq ft, but box and bundle coverage are the manufacturer’s numbers and change with exposure — a tighter cedar coursing needs more bundles than a looser one; always round up, and consider buying one extra unit from the same dye/production lot so a later repair matches; and keep the waste factor separate from the round-up so you can see each cushion. Common mistakes: dividing by the square (100) when the material actually ships in 200 sq ft boxes and doubling the count; forgetting waste entirely; and trusting a rule of thumb over the coverage printed on the manufacturer’s installation instructions. These are labeled planning typicals — confirm the stated coverage for your exact product; this tool plans quantity, not moisture, flashing or structural condition.
Reference table
| Material | Typical exposure | Coverage per unit |
|---|---|---|
| Vinyl lap (double-4") | 8" per panel | 200 sq ft / box |
| Vinyl lap (double-5") | 10" per panel | 200 sq ft / box |
| Insulated vinyl | 6–7" | 200 sq ft / box |
| Cedar shingle / shake | ~5–8" | 25 sq ft / bundle |
| Fiber cement lap plank | 4–8" (plank) | 100 sq ft / square |
| Engineered wood lap | 4–8" | 100 sq ft / square |
| Wood / cedar bevel lap | 4–8" | 100 sq ft / square |
| Steel / aluminum lap | 8" | 100 sq ft / square |
| Board & batten | board width | 100 sq ft / square |
Labeled published planning snapshot — 1 square = 100 sq ft. Fiber cement, engineered wood, wood and metal lap are commonly sold and quoted by the square (100 sq ft) rather than a fixed box; confirm the exact pieces-per-square and stated coverage on the manufacturer’s installation instructions.