Bio urn buying checklist: what to confirm before you order
Before you order a bio urn, confirm four things: it holds your pet's full volume of ashes, it's made for where you'll use it (soil, water or a pot), you have a spot you're allowed to use for years, and you have a plan to dilute the ash so it doesn't harm the plant. The rest is timing, keepsakes and the returns policy.
By the Bio Urns & Eco Memorials editorial team · Updated September 24, 2026 · 5 min read · Sources
- Size the urn from your pet's weight
- Match the urn to soil, water or a container
- Plan the site, the soil and the date first
The short answer
What should you check before buying a bio urn?
Capacity, setting, site and soil. If the urn is too small, it can't hold all of your pet's remains. If it's made for water and you plant it, or the reverse, it won't behave as you hoped. And if you don't have a place and a plan for the alkaline ash, even a lovely kit can end with a struggling plant.
Most people buy a bio urn within a couple of weeks of their pet's death, often while waiting for the ashes to come back; many families receive private cremation remains within about 5-10 days[1]. That's a short window for a lasting decision, so this list is designed to be worked through quickly. Tick what applies and skip what doesn't.
Check 1
Is the urn big enough for your pet's ashes?
The common rule of thumb in the urn trade is one cubic inch of space per pound of body weight. That works out to about 12 cubic inches for a 12 lb cat and 70 for a 70 lb dog[2]. Remains typically weigh about 3-5% of body weight[3], so by our estimate a 12 lb cat returns roughly 6.7 oz[4] and a rabbit only about 74 g[5].
- ☐ Find your pet's healthy adult weight, not a weight after illness.
- ☐ Read the urn's capacity in cubic inches, not just 'small', 'medium' or 'large'.
- ☐ Leave a little headroom if the kit asks you to mix in an amendment.
- ☐ For giant breeds, expect around 3.8 lb[6] of remains and confirm the design comes that large.
The urn size calculator does the arithmetic from your pet's weight. If the numbers don't fit, you can split the ashes between two urns or keep a portion aside, which we cover in check 7.
Free tool
Urn size calculator
Find the urn volume you need from your pet's weight, plus keepsake and sharing options.
Checks 2 and 3
Where will the urn go, and does it include a plant?
Check 2: the setting. Bio urns are built for a particular job, and the material follows from it. Pick yours from this short list before you browse:
- ☐ In the ground with a tree or shrub: a planting urn with a growing pocket.
- ☐ In the ground with no plant: a simple burial urn in paper, fiber or unfired clay.
- ☐ In water: a water-soluble urn in paper, salt, sand or gelatin.
- ☐ On a shelf now, in the ground later: a sturdy fiber or paper urn that stays dry indoors, or a display urn plus a separate bio urn for later.
Our explainer on biodegradable urn materials shows which ones suit soil, water or both, and the soil vs water comparison helps if you're torn between them.
Check 3: plant or no plant. Kits vary. The Bios Urn for pets includes a seed capsule for $99[7], while The Living Urn's pet system is $119[8] without a tree. If a sapling is sold separately, ask when it ships, because many sellers only send trees in spring or fall. Our piece on how a tree urn works explains the seed-versus-sapling trade-off.
If you rent or might move, how would you handle a memorial planting?
Tap an answer to vote and see how others answered. Anonymous.
Checks 4 and 5
Do you have a spot, permission and a soil plan?
Check 4: the site. A tree memorial is a commitment of decades, so think about who controls the ground.
- ☐ Do you own the land, or will a landlord, HOA or relative need to agree?
- ☐ Are you likely to move in the next five years? If so, a large container might suit better.
- ☐ Is there room for the mature spread, away from foundations, pipes and wires?
- ☐ Have you called your local utility-marking service (811 in the US) before digging?
- ☐ For water, do you know who manages the lake, river or shoreline, and have you asked?
Our article on legal questions before scattering goes through yards, rentals, parks and beaches in more detail.
Check 5: the soil plan. Pet ashes test at a pH of about 11.7[9], far above what most plants like. A biodegradable shell doesn't change that. Before you order, decide how you'll dilute the ash: mixed through plenty of compost and soil, perhaps with an acidic amendment, then checked with an inexpensive pH kit. Some gardeners let the mix rest for 90–120 days[10]. Our soil-mix guide gives starting amounts by pet size. If you plan to add a sapling, Iowa State University's tree planting basics are worth reading before you order, since the size of the hole decides how much blend you'll need.
Checks 6 and 7
When will it arrive, and will you keep a portion back?
Check 6: delivery and timing. Work backward from the day you have in mind.
- ☐ When will the ashes be back from the crematory?
- ☐ How long does the urn take to ship, and does a sapling ship separately?
- ☐ Is the ground workable then, or frozen, baked hard or waterlogged?
- ☐ Will the people you want there be free? The farewell planner helps set a date and a simple order for the day.
Free tool
Farewell & memorial service planner
Build a simple goodbye: who, where, readings, rituals and a checklist.
Check 7: a keepsake portion. Once ashes go into soil or water, you can't get them back. Many families set aside a spoonful first for a small urn, a pendant or a second planting. One retailer lists keepsake or mini pet urns at about $15–$60[11]. Splitting also helps with a large dog whose full remains exceed the bio urn's capacity.
Checks 8 and 9
What should you confirm with the seller?
Check 8: materials and claims. Ask what the urn is made of, including glues, dyes, liners and coatings, and how it behaves in your setting. A vague answer is a reason to look elsewhere.
Check 9: returns and damage. Grief and shipping don't mix well, so read the policy before you buy.
- ☐ Can you return an unused urn if plans change?
- ☐ What happens if it arrives cracked or damp?
- ☐ If a sapling dies soon after arrival, is there a replacement policy?
- ☐ Is engraving or personalization non-returnable? One retailer says name-only engraving usually adds $15–$25[12] on a standard pet urn, so ask before adding it to a biodegradable one.
| Check | Question | Done? |
|---|---|---|
| 1. Capacity | Does it hold my pet's full remains? | ☐ |
| 2. Setting | Soil, water, container or display first? | ☐ |
| 3. Plant | Seed, sapling, or nothing included? | ☐ |
| 4. Site | Can I use this spot for years? | ☐ |
| 5. Soil plan | How will I dilute and test the ash? | ☐ |
| 6. Timing | Will ashes, urn and tree line up? | ☐ |
| 7. Keepsake | Am I keeping a portion back? | ☐ |
| 8. Materials | Do I know what it's made of? | ☐ |
| 9. Returns | What if it's damaged or plans change? | ☐ |
If you'd rather hand the checking to someone else, send us your pet's details and where you're hoping to plant or release. We'll reply by email with urns that pass these checks, plus current prices. You can also compare every urn type on our services page. For climate notes where you live, see our location pages, and the poll results show how other readers are handling renting and keepsakes.
Reader polls
What would you choose?
Vote anonymously and see how other readers answered. The results are live counts from people who visit this site, so they show real opinions, not a scientific sample.
If you rent or might move, how would you handle a memorial planting?
Tap an answer to vote and see how others answered. Anonymous.
Which memorial feels most like your pet?
Tap an answer to vote and see how others answered. Anonymous.
Do you keep more than one memorial for the same pet?
Tap an answer to vote and see how others answered. Anonymous.
Questions people ask
How do I know how much ash I'll get back?
Ask the crematory; they can usually give a close estimate. As a rough guide, remains weigh a few percent of body weight, so cats and small dogs return a few ounces while large dogs return a pound or more. Aquamation often returns a little more material than flame cremation, which is worth knowing when sizing an urn.
Can I buy a bio urn before my pet has died?
Yes, and some people find it eases the days afterward. Store it somewhere dry, since paper and fiber urns soften in damp conditions, and keep the packaging in case you need to return it. Buying ahead also lets you plan the site and soil in a calm season.
What if I'm not sure whether I'll plant or release in water?
Choose an urn made from paper or unfired clay, which works in both settings, or keep the ashes in their sealed bag until you decide. There's no deadline. Many families wait for a season, an anniversary or a family gathering before choosing.
Should I avoid engraving a biodegradable urn?
Not necessarily, but think about where the engraving will end up. On a buried or dissolving urn, nobody will see it after the day itself. Many families engrave a small stone or marker for the planting spot instead, which lasts and can be visited. Check whether personalized urns can be returned before ordering.
Do I need to tell anyone before planting ashes in my own yard?
In most cases no one needs to approve a small planting on land you own, but check any HOA rules and deed restrictions. If you rent, ask your landlord. Before digging, contact your local utility-marking service so you don't hit a buried cable or pipe.
Is it worth paying more for a kit with a tree included?
It depends on your time and your region. A kit with a sapling saves you finding a nursery and matching a tree to the urn, but the species list may be narrower. A local nursery tree suited to your climate, paired with a simple biodegradable urn and good compost, can do just as well and may cost less.
Sources and our estimates
- [1] A US aftercare guide says many families receive private cremation ashes within about one to two weeks, with 5-10 days commonly quoted. Funeral.com - Pet Cremation Timelines: How Long Until Ashes Are Returned, 2026.
- [2] Using the industry rule of thumb of 1 cubic inch of urn space per pound of body weight, a 12 lb cat needs an urn of about 12 cubic inches; a 70 lb dog needs about 70 cubic inches. Our estimate: urn cu in = body weight lb x 1 (industry rule of thumb, not a measured value). How we calculate.
- [3] Embrace notes cremated remains typically weigh about 3-5% of the pet's original body weight. Embrace Pet Insurance - Bury or Cremate Your Dog? Costs, Pros & Cons, 2025.
- [4] A 12 lb cat would be expected to return about 6.7 oz (0.42 lb) of cremated remains. Our estimate: 12 lb x 3.5% x 16 oz/lb. How we calculate.
- [5] A median-weight adult pet rabbit (2.1 kg) would be expected to return about 74 g (2.6 oz) of cremated remains. Our estimate: 2,100 g x 3.5%. How we calculate.
- [6] A median-weight giant-breed dog (48.8 kg / 108 lb) would be expected to return about 1.71 kg (3.8 lb) of cremated remains, needing an urn of about 108 cubic inches. Our estimate: 48.8 kg x 3.5% x 2.2046 lb/kg; urn = 108 lb x 1 cu in/lb. How we calculate.
- [7] The Bios Urn for pets, a biodegradable urn with a seed capsule, costs $99. Bios Urn – Pets, 2026.
- [8] The Living Urn's pet bio-urn planting system (without a tree) costs $119. The Living Urn – Pet tree urn, 2026.
- [9] Cremated remains have a very high pH of approximately 11.7, which is toxic to plants without amendment. Larkspur Conservation — Giving Cremated Remains a New Life Through Science, 2024.
- [10] Gardening Know How advises letting an ash/soil-amendment mixture sit for at least 90 to 120 days before planting. Gardening Know How — Planting With Cremains: Is There a Safe Way to Bury Ashes, 2024.
- [11] Keepsake or mini pet urns cost about $15–$60, versus $25–$100 for small and $40–$200 for medium urns (Memorials.com). Memorials.com – Pet Urn Cost Guide, 2025.
- [12] Simple name-only engraving on a pet urn typically adds $15–$25; name plus dates adds $25–$40. Memorials.com – Pet Urn Cost Guide, 2025.
Want us to check an urn for you?
Tell us what you need and where you are. We'll reply by email with clear options and prices so you can decide in your own time.