★ REFERENCE TABLE · CONSTRUCTION · PLYWOOD
The number on the label is not the thickness in the sheet. Sanded plywood actuals commonly run 1/32 in under nominal, so a sheet sold as 3/4 in is actually 23/32 in (0.719 in, 18.26 mm) and weighs about 68 lb as a 4×8 sheet. At the defaults below — 3/4 in plywood over 100 sq ft, no waste allowance — you need 4 sheets (100 ÷ 32 = 3.13, rounded up), weighing about 272 lb in total. Use the chart to check the real thickness before you cut, and the calculator to buy the right number of sheets.
Pick the nominal thickness from the chart, enter the wall or floor area, and tick the waste box if you will cut around doors, windows, or odd corners. Each 4×8 sheet covers 32 sq ft; the calculator divides, applies the 10% waste allowance when ticked, and always rounds up — you cannot buy a fraction of a sheet.
Table basis, stated plainly: every row below assumes sanded plywood, whose actual thickness commonly runs 1/32 in under the nominal label. Actual fraction = nominal − 1/32 in; decimal inches are the exact fraction value rounded to three decimals; millimetres = decimal inches × 25.4, rounded to two decimals; weights are approximate typical weights for a 4×8 softwood sheet and vary with species, glue, and moisture. Unsanded or specialty panels can differ — measure a sheet with calipers when the thickness matters to a joint, a dado, or a shelf fit.
| Nominal thickness | Actual thickness | Decimal (in) | Millimetres | Typical 4×8 weight |
|---|---|---|---|---|
| 1/4 in | 7/32 in | 0.219 | 5.56 mm | ~21 lb |
| 3/8 in | 11/32 in | 0.344 | 8.73 mm | ~33 lb |
| 1/2 in | 15/32 in | 0.469 | 11.91 mm | ~45 lb |
| 5/8 in | 19/32 in | 0.594 | 15.08 mm | ~56 lb |
| 3/4 in | 23/32 in | 0.719 | 18.26 mm | ~68 lb |
| 1-1/8 in | 1-3/32 in | 1.094 | 27.78 mm | ~104 lb |
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Setup: nominal 3/4 in, area 100 sq ft, no waste allowance.
Line 1 — the actual thickness. 3/4 in − 1/32 in = 23/32 in = 0.719 in; 0.719 × 25.4 = 18.26 mm.
Line 2 — the raw sheet count. 100 ÷ 32 = 3.13 sheets before rounding.
Line 3 — the buy count. Round 3.13 up to 4 sheets, because a part-sheet cannot be bought.
Line 4 — the weight. 4 × ~68 lb = about 272 lb to haul and handle.
A nominal 1/2 in sheet is actually 15/32 in = 0.469 in = 11.91 mm and weighs about 45 lb as a 4×8 sheet. Over the same 100 sq ft it still needs 4 sheets (the thickness does not change the coverage), but the load drops to about 180 lb — a meaningful difference on a roof or a second floor.
A nominal 1-1/8 in sheet is actually 1-3/32 in = 1.094 in = 27.78 mm and weighs about 104 lb per 4×8 sheet. Four sheets for 100 sq ft weigh about 416 lb: plan for two people and a vehicle that can carry the weight, not just the size.
At 100 sq ft the waste toggle changes nothing: 3.13 sheets without waste and 3.44 sheets with 10% waste (3.13 × 1.10) both round up to 4 sheets. The toggle only bites when the extra 10% crosses a whole sheet — at 96 sq ft, 3.00 sheets without waste becomes 3.30 with waste, so the buy count rises from 3 sheets (~204 lb at 3/4 in) to 4 sheets (~272 lb). That is exactly when waste allowance earns its keep: one short sheet means a second trip.
| Output | Formula | What it means |
|---|---|---|
| Actual thickness | nominal − 1/32 in; mm = in × 25.4 | 23/32 in (0.719 in, 18.26 mm) for the 3/4 in default — the thickness your joints must fit. |
| Raw sheet count | area ÷ 32 | 3.13 for 100 sq ft — the exact coverage before rounding. |
| Sheets to buy | ceil(raw × 1.10 if waste, else raw) | 4 sheets at the defaults — always rounded up, because part-sheets are not sold. |
| Total weight | sheets × per-sheet weight | ~272 lb at the defaults — what you actually have to carry. |
Actual thicknesses follow the stated sanded-plywood convention (nominal minus 1/32 in) and are consistent across all six rows; millimetre values are the exact decimal × 25.4 rounded to two decimals. Real sheets vary: unsanded panels run thicker, hardwood-plywood cores differ from softwood, moisture swells panels, and manufacturers work to tolerances, so a caliper measurement beats this table when a fit is tight. Weights are approximate typical values for softwood 4×8 sheets, not guarantees, and they scale with thickness rather than being weighed per brand. The sheets calculator counts full-sheet coverage only — it does not optimize cuts, account for stud spacing waste, or subtract door and window openings from the area you enter. Error policy: a non-positive area and a thickness outside the list are reported as errors rather than modeled.
Bright Side Kit. "Plywood Thickness Chart: Sizes and Sheets." https://brightoolbox.com/plywood-thickness-chart/ Accessed October 24, 2026.Data sourcesUsually 23/32 in, or 0.719 in (18.26 mm). Sanded plywood actuals commonly run 1/32 in under the nominal label, so the number on the shelf is not the number in the sheet. Measure with calipers when a joint has to fit.
Because the nominal size is a label from before sanding and finishing. Sanding removes material, and the trade convention is that sanded sheets run about 1/32 in under nominal. Unsanded panels can run closer to nominal, which is another reason to measure.
Four sheets. One 4×8 sheet covers 32 sq ft, so 100 ÷ 32 = 3.13 sheets, rounded up to 4. With a 10% waste allowance the raw count is 3.44, which still rounds to 4 — the waste allowance only changes the answer when it crosses a whole sheet.
About 68 lb for a typical 4×8 softwood sheet. Weight varies with species, glue, and moisture, and it scales with thickness: about 45 lb at 1/2 in and about 104 lb at 1-1/8 in. Plan the vehicle and the lifting around the total, not one sheet.
11.91 mm at its actual thickness of 15/32 in (0.469 in). Multiply the actual decimal inches by 25.4: 0.469 × 25.4 = 11.91 mm. Note that this is the actual size, not the nominal 1/2 in, which would be 12.70 mm.
Yes, whenever you cut around openings or irregular edges. The calculator's 10% allowance multiplies the raw count by 1.10 before rounding up. For a plain rectangle with no cuts, no allowance is fine; for walls with doors and windows, one extra sheet beats a second trip.