Choosing an urn is a very personable and mostly upsetting, emotional experience. If you're shopping for an urn, you've either lost a pet, or know someone who has. Firstly, we are sending our biggest hugs. It's not an easy time, and purchasing an urn may be the last thing you want to do. At Rest By Me, we hopefully can make this experience a little easier.
Finding the right urn is about finding a piece that feels right sitting in your home: on a shelf, a mantel, or a bedside table. You want to find an urn that holds your pet's memory the way it deserves to be held. Size is important, practically speaking, and getting it right the first time means one less thing to think about.
As a general rule, cremated remains take up about 16–36 mL per kilogram of your pet's body weight before cremation (roughly one cubic inch per pound). An example may be, an 18 kg dog needing an urn around 650 mL; a 4.5 kg cat might need around 160 mL.
The General Rule for Urn Sizing
Cremated remains take up approximately one cubic inch of space per pound of your pet's body weight before cremation, or in metric terms, roughly weight in kilograms × 36 = capacity in millilitres.
This is a starting point rather than an exact science. Ash volume can vary depending on bone density, age, and the cremation process itself, so it's worth sizing up if your pet's weight sits on the edge of a bracket.
Quick conversion reference
| Pet weight | Capacity needed |
|---|---|
| 4.5 kg (10 lbs) | ~160 mL |
| 9 kg (20 lbs) | ~330 mL |
| 18 kg (40 lbs) | ~650 mL |
| 23 kg (50 lbs) | ~820 mL |
| 41 kg (90 lbs) | ~1475 mL |
What Size Urn Do I Need for My Dog?
This is one of the most common questions we hear, and it depends entirely on your dog's weight.
Small dogs (under 9 kg / 20 lbs)
Look for urns with at least 330–490 mL of capacity. Our Round Beechwood Pet Urn with Leather Collar is a good starting point to check against, confirm capacity on the listing before choosing.
Medium dogs (9–23 kg / 20–50 lbs)
Aim for 820–1150 mL. Pieces like the Beechwood Wrapped Dog Urn or 4 Legged Sand Resin Pet Urn sit in this range, just make sure to check the listed capacity on each to confirm the fit for your dog's weight.
Large dogs (23–41 kg / 50–90 lbs)
You'll want 1475–1965 mL or more. Browse our full Dog Urns collection to compare capacities at this size.
Giant breeds (41 kg+ / 90 lbs+)
Capacity above 1965 mL, or consider whether a larger memorial piece suits the space better, see our Large Breed / Larger Size Urns collection.
If your dog's weight sits right on the edge of a range, size up rather than down — an urn that's slightly larger will always hold the remains comfortably, while one that's too small won't.
What Size Urn Do I Need for My Cat?
Most cats fall between 3–6 kg, which typically needs 110–220 mL of capacity. Our Cat Urns collection lists exact capacity on every product page, so you can match it precisely to your cat's weight.
Choosing a Keepsake or Shared Urn Instead
Some people choose to divide their pet's ashes, a small keepsake urn for a shelf, with the remainder kept elsewhere or scattered somewhere that mattered to them. If that's the plan, you won't need a full-capacity urn at all. Our keepsake pieces are figurines designed for exactly this, holding a small, symbolic portion rather than the full amount, or you can choose our memorial posts.
FAQs
Do I need to know my pet's exact weight before ordering? An estimate is fine, sizing brackets allow some margin. If you're unsure, we'd always recommend rounding up.
What happens if I choose an urn that's too small? Some ash may not fit, which usually means splitting the remains and potentially scattering some in their favourite spot outside.
Is the cubic-inch-per-pound rule exact? No, it's a general industry guide, not a guarantee. Actual ash volume depends on the individual animal. Check the listed capacity on each product page for the most accurate figure.
Can I still choose an urn based on how it looks rather than strict capacity? Yes, as long as it meets the minimum capacity for your pet's weight. Beyond that, choice comes down to what feels right for your space.
