Urn Capacity Guide: Choosing the Right Size, in Cubic Inches
North America sizes urns by internal capacity, in cubic inches — not by how tall a box looks on a shelf. This guide gives the working rules the trade uses, for adult urns, pet urns and keepsakes.
The one rule that does most of the work
Cremated remains take up about 1 cubic inch per pound of body weight before cremation. A person of 180 lb needs an urn of at least 180 cubic inches; a 40 lb dog needs about 40. When the result falls between two sizes, choose the larger — a slightly roomy urn is invisible; one that is too small is a problem discovered at the worst possible moment.
Capacity by weight
Adult urns
| Person’s weight | Minimum capacity (cubic inches) |
|---|---|
| 120 lb | 120 |
| 160 lb | 160 |
| 200 lb | 200 |
| 240 lb | 240 |
| Two people (companion) | 350–440 |
Pet urns
| Pet’s weight | Recommended capacity (cubic inches) |
|---|---|
| Up to 15 lb | 15–20 |
| 16–35 lb | 35–45 |
| 36–55 lb | 55–70 |
| 56–85 lb | 85–100 |
| 86–120 lb | 120–140 |
Keepsakes hold a portion
Keepsake urns (typically 3–25 cu in) and cremation jewelry (under 1 cu in) hold part of the remains so several family members can each keep a portion. They are sized by intent, not by body weight.
Three sizing mistakes to avoid
1. Judging by outside dimensions
Wall thickness and bases eat volume; only tested internal capacity counts.
2. Trusting a catalogue number
Factory catalogue capacities are often nominal. Erdengobi spec sheets state tested capacity, verified at inspection.
3. Forgetting the temporary container
Remains usually arrive in a temporary container; allow transfer room rather than matching its volume exactly.