About this tool
For the lump on the ground with no paperwork on it. Material, shape, dimensions — an honest estimate in kilograms and pounds.
The densities used
These are the standard handbook figures for construction materials. The calculator works in kg/m³ and converts; the lb/ft³ column is the same number in the other system.
| Material | kg/m³ | lb/ft³ |
|---|---|---|
| Concrete — reinforced | 2,400 | 150 |
| Concrete — plain | 2,300 | 144 |
| Steel | 7,850 | 490 |
| Aluminium | 2,700 | 169 |
| Lumber — dry softwood | 500 | 31 |
| Lumber — green softwood | 640 | 40 |
| Water | 1,000 | 62 |
| Soil / earth — loose | 1,300 | 81 |
| Soil / earth — compacted | 1,750 | 109 |
| Gravel / crushed rock — dry | 1,600 | 100 |
| Gravel / crushed rock — wet | 1,900 | 119 |
| Sand — dry | 1,600 | 100 |
Read these as typical, not exact. Concrete varies with mix and reinforcement. Wood varies enormously with species and moisture — the same beam can put on a third of its weight again after a wet week, which is why green and dry are listed separately. Soil and gravel change with compaction and water. If the number matters, weigh it or find the paperwork.
What this does not include
- Anything stuck to it. Ice, mud, standing water, snow on a stack — all real weight, none of it in the dimensions.
- The rigging. Slings, spreader bars, shackles and the block itself all hang off the hook too. The rigging planner adds those back in.
- Voids and openings. A slab with a stair opening in it is lighter than the rectangle you measured; a hollow-core plank is much lighter than solid.
- Where the weight sits. An estimate of total weight says nothing about balance. That is the centre of gravity tool.
Rounded up. This is an estimate off a handbook density, not a weighing — always check it against the shipping papers, the shop drawing or the mill certificate before you rig it.