Estimate granite slab weight from dimensions, area, or per-square-foot thickness using standard or custom density in lb and kg for countertops.
Granite Weight Formula
The calculator uses one of three forms depending on which tab you select.
From dimensions:
Weight = Length × Width × Thickness × Density
From area:
Weight = Area × Thickness × Density
Per square foot (surface load):
Load = Thickness × Density
- Length, Width, Thickness — slab dimensions, converted to feet
- Area — slab face area, converted to ft²
- Density — granite density in lb/ft³ (default 168 lb/ft³)
- Weight — total weight in pounds (also shown in kg)
- Load — weight per unit area in lb/ft² (also shown in kg/m²)
Granite density varies by type and porosity. Most commercial granite falls between 160 and 185 lb/ft³, so results are estimates. The calculator does not subtract sink or cooktop cutouts, so subtract those areas from your input if you need a net weight.
Typical Granite Weights and Densities
Use these tables to sanity check your result or to pick a density when the supplier has not given one.
| Slab thickness | Weight per ft² | Weight per m² |
|---|---|---|
| 2 cm (¾ in) | ~11 lb | ~54 kg |
| 3 cm (1¼ in) | ~16.5 lb | ~81 kg |
| 2 in | ~28 lb | ~137 kg |
| 3 in | ~42 lb | ~205 kg |
| Granite type | Density (lb/ft³) | Density (kg/m³) |
|---|---|---|
| Light granite | 160 | 2,560 |
| Average granite | 168 | 2,690 |
| Dense granite | 175 | 2,800 |
| Very dense granite | 185 | 2,960 |
Example and FAQ
Example: A kitchen countertop measures 96 in × 26 in at 3 cm thick. Convert to feet: 8 ft × 2.167 ft × 0.0984 ft = 1.706 ft³. Multiply by 168 lb/ft³ to get about 287 lb.
How heavy is a standard 3 cm granite countertop? Roughly 16 to 19 lb per square foot. A 50 ft² kitchen typically runs 800 to 950 lb installed.
Should I use 2 cm or 3 cm for my calculation? Use what the fabricator quoted. If unknown, 3 cm is the most common thickness for kitchen counters in the US, while 2 cm is more typical in bathrooms and Europe.
Does the result include the sink cutout? No. Subtract the cutout area from your input if you need the net weight after fabrication.
Why does my supplier’s number differ? Densities range from 160 to 185 lb/ft³ depending on the stone. Switch the density selector or enter a custom value to match the spec sheet.
