Choosing an urn is one of the last practical decisions you make for a pet, and it is usually made quickly, in the middle of everything else. Only one number really matters, and it is easy to get before you order — the rest is detail worth checking once you know the size.
Written by the COAZEN team
The short answer
Ashes take up roughly one cubic inch of volume for every pound of body weight. A 40 lb dog therefore needs somewhere in the region of 40 cubic inches. Treat that as a starting point rather than a guarantee — and if your cremation provider has given you a volume, use their number instead of the estimate.
The rule of thumb, in numbers
| Body weight | Approximate volume needed | Note |
|---|---|---|
| 10 lb | ≈ 10 cubic inches | Small urn or a keepsake-size container |
| 20 lb | ≈ 20 cubic inches | Between two sizes — take the larger |
| 40 lb | ≈ 40 cubic inches | The middle of the range for most dogs |
| 70 lb | ≈ 70 cubic inches | Check the interior depth, not just the footprint |
| 100 lb | ≈ 100 cubic inches | Measure the shelf before you commit |
These figures come from the one-cubic-inch-per-pound rule, not from any individual product. The actual figure varies with bone density, the cremation process and how finely the remains are processed, and different providers give slightly different numbers.
Step by step: working out what you need
- Find the weight. Use their most recent healthy weight rather than a guess from a photograph. If you are between two figures, use the higher one.
- Ask your provider for the volume. If you are arranging the cremation yourself, ask before you shop. If it has already happened, the container the ashes were returned in usually states the weight or volume.
- Convert, then add headroom. Multiply pounds by one for a rough cubic-inch figure, then add a margin — it is easier to live with a container that is a touch generous than one that is tight.
- Check the piece’s stated range. Each product page states the weight range a size is designed for. Match your figure to that range, not to a photograph.
- Measure where it will sit. Shelf, mantel or cabinet — measure first. An urn that does not fit the space is a decision you only want to make once.
What else is worth checking
| Check | Why it matters | Where to find it |
|---|---|---|
| Lid type | A removable lid versus a threaded or sealed closure matters if it will be moved | The product page, or ask us |
| Lined interior | Protects the finish from the inside and keeps contents contained | The product page |
| Footprint and height | A large urn on a narrow shelf is a problem you cannot undo | Measure your space, then compare |
| What can be personalized | Name, dates and a short inscription are the usual options | Each product page lists exactly what that piece allows |
| Whether a portion is being split | If some ashes go into jewellery, the urn needs to hold slightly less | Decide before ordering, not after |
Sizes on this site
Our memorial urns are offered in size ranges rather than exact volumes, and each product page states the weight range that size is designed for. If your pet falls near a boundary, or you have a volume figure from your provider you would like checked against a piece, send us the numbers before you order and we will confirm which size fits. Our size guide covers the measuring side in more detail.
If you are also keeping some ashes elsewhere
Splitting the ashes is common — most in an urn at home, a small portion in a piece of jewellery that travels. If you plan to do this, work out the split before you buy the urn, because the volume needed drops accordingly. It is easier to decide this once than to discover the urn is fuller than expected.
Our guide to what to do with your pet’s ashes covers the wider decision if you have not settled on keeping them at home.
One thing people regret
The most common regret is not the size but the timing: buying in the first week, before the ashes have come back, and guessing. If you can wait until the container is in your hands, the number is on it.
Questions people ask
Is one cubic inch per pound accurate?
It is a widely used rule of thumb, not a precise measurement. It is close enough to choose a size band, but if you have a volume figure from your provider, that figure is always the better number to use.
What if the ashes have already been returned in a container?
The container usually states the weight or volume. If it does not, ask the provider — most will confirm it, and it saves guessing from the pet’s weight.
Should I buy slightly larger than I need?
Usually yes, especially if you may add a clipping of fur, a collar tag or a note. A container that is a little generous is easier to live with than one that is tight, and the difference in footprint is often small.
Can the urn be personalised after it is made?
No — engraving is done during making. Settle the name, dates and wording before you order, and reply to the confirmation email within 48 hours if anything needs changing.
Next step
You can see the full range in memorial keepsakes, or start with the walnut memorial urn. If you are working towards a date, tell us the product and the date you need before ordering rather than afterwards.
