A puppy grows so fast that a crate bought for its size today can be too small in weeks. Buying a new crate every few months is expensive and wasteful, and buying one large crate and leaving it open leads to house-training problems. The answer used by many owners is the middle path: one adult-size crate and a divider. This guide explains how to choose the crate, how to set the divider, how to measure as your puppy grows and when the divider can come out.
The two sizes you need to know
Two measurements matter, and they change at different speeds:
- The crate size. This is chosen once, from the expected adult length and height plus the allowance.
- The usable space. This is set from the puppy’s current length and height plus the allowance, and moves as the puppy grows.
Your puppy’s length (nose to base of tail) and height (floor to the top of the head or ears, standing) are the two numbers. Our guide to what size crate a dog needs explains how to measure, and the Dog Crate Size Calculator turns them into a minimum inside size.
Step 1: estimate adult size
The adult size is an estimate, and it may be the hardest part. A breeder or rescue can often tell you how big the parents are. For a mixed-breed puppy, your vet can give a range based on the puppy’s age, paws and growth. Choose the crate for the top of the range, because a crate with a divider can be used at a smaller setting, but a crate that is too small cannot be stretched.
Once the puppy is a few months old, re-estimate with your vet. If the puppy is growing larger than expected, you can check with the calculator whether the crate still fits.
Step 2: buy the adult-size crate
Take the expected adult length and height, add 5 to 10 cm (2 to 4 in) to each, and compare with the crate’s inside measurements, as set out in our dog crate size chart. Choose a crate that includes a divider or one that can accept an aftermarket divider. Check that:
- The inside height is enough for the standing adult.
- The door is large enough for an adult dog to walk through.
- The divider is sturdy and cannot be chewed, pushed or knocked over.
- The tray is easy to clean, since puppies have accidents.
Step 3: set the divider for today
The usable space is the puppy’s current length and height plus the allowance. Because most crates are tall enough from the start for a puppy, the divider mainly changes the length.
| Puppy length now | Usable length (+5 cm) | Usable length (+10 cm) | In inches (+10 cm) |
|---|---|---|---|
| 25 cm (10 in) | 30 cm | 35 cm | 14 in |
| 30 cm (12 in) | 35 cm | 40 cm | 16 in |
| 40 cm (16 in) | 45 cm | 50 cm | 20 in |
| 50 cm (20 in) | 55 cm | 60 cm | 24 in |
| 60 cm (24 in) | 65 cm | 70 cm | 28 in |
| 70 cm (28 in) | 75 cm | 80 cm | 31 in |
Place the divider so that the space from the back wall to the divider equals the usable length. Make sure the puppy can stand without touching the roof, turn round and lie down stretched out.
Step 4: measure every two weeks
Growth is not steady, so a regular measuring day helps. In the fast-growing months, measure every two weeks and keep a note.
| Date | Age in weeks | Length | Height | Usable length now | Divider set to |
|---|---|---|---|---|---|
The Puppy & Kitten Age Calculator tells you the age in weeks from the birth date, which helps you match measurements to age. If the puppy’s nose touches the divider when it stretches out, or it cannot turn without bumping the sides, move the divider back.
A worked example
A puppy’s expected adult size is 70 cm long and 52 cm tall.
- Adult crate: 70 + 10 = 80 cm long and 52 + 10 = 62 cm high inside at the minimum.
- The puppy is now 30 cm long and 25 cm tall.
- Usable length: 30 + 10 = 40 cm. The divider is set 40 cm from the back wall.
- Two weeks later the puppy is 36 cm long. Usable length: 46 cm. Move the divider to 46 cm.
- Continue until the puppy reaches 70 cm. At 70 cm the usable space is 80 cm, which is the full crate, so the divider comes out.
One crate does the job of four.
Why not a big crate from the start?
An open large crate looks generous, but a young puppy has little control of its bladder and bowels and may use one end as a toilet and sleep in the other. The space also loses its den-like feeling, which helps many dogs settle. A divider keeps the puppy in a space that is sized for sleeping, with toilet breaks outside at regular times. Your vet or a qualified trainer can advise on a house-training routine for your puppy’s age.
How a crate fits into a puppy’s day
A crate is a resting place, not a place to leave a puppy for long stretches. Young puppies need frequent toilet breaks, meals, play and company. Introduce the crate gradually, with a comfortable bed, a treat or a chew and the door open at first. Never use it for punishment. Ask your vet or a trainer for a schedule suited to your puppy’s age and temperament, because the right amount of crate time differs by puppy.
If you are feeding a puppy several meals a day, plan toilet breaks after meals; our guide on how much to feed a puppy shows meal frequency by age.
When to remove the divider
Remove the divider when the puppy’s usable space matches the full crate, in other words, when the puppy’s current length plus the allowance reaches the crate’s inside length. At that point the dog can stand, turn and stretch out in the whole crate. If your puppy stops growing before it fills the crate, the crate may be larger than needed; you can keep a partial divider in place to keep the den feel.
Special cases
- Chewers. A puppy that chews the divider needs a stronger one or a different setup; ask the maker or a trainer.
- Long-bodied, short-legged puppies. Length changes more than height, so the divider matters more.
- Fast-growing large breeds. Measure weekly if you find the puppy is outgrowing the setting quickly.
- Puppies that do not like the crate. Slow introduction and positive experiences matter more than size; ask a trainer.
Common mistakes
- Buying a crate sized for the puppy today.
- Leaving a large crate open with no divider.
- Forgetting to move the divider as the puppy grows.
- Measuring only once.
- Using the crate for long periods or as punishment.
- Not checking that the divider is secure.
A month-by-month example
A puppy expected to reach 70 cm in length (a medium to large dog) grows like this. Numbers are illustrations.
| Age | Puppy length | Usable length (+10 cm) | Divider position (from the back wall) | Full crate inside length (80 cm) |
|---|---|---|---|---|
| 8 weeks | 30 cm | 40 cm | 40 cm | half the crate unused |
| 12 weeks | 38 cm | 48 cm | 48 cm | 60% used |
| 16 weeks | 46 cm | 56 cm | 56 cm | 70% used |
| 6 months | 58 cm | 68 cm | 68 cm | 85% used |
| 9 months | 66 cm | 76 cm | 76 cm | 95% used |
| 12 months | 70 cm | 80 cm | removed | full |
The numbers show why a single small crate would be outgrown by week 12, and why a divider saves buying three crates. Your puppy’s growth will not match these figures exactly, so measure rather than use the table.
Choosing a divider
Dividers differ. Check:
- Material. Metal wire dividers are sturdy; plastic or fabric ones can be chewed.
- Fit. The divider should be secure, with no gaps where a paw or head could be trapped.
- Adjustability. Can it be moved in small steps?
- Compatibility. Is it made for your model of crate?
- Safety. Smooth edges and secure fastenings.
A divider that is chewed or can be pushed over is a hazard, so supervise a new puppy at first and stop using a damaged divider.
Other ways to size the space
If your crate has no divider, you can:
- Buy a crate with a divider next time.
- Use a second, smaller crate for the early weeks, and pass it on afterwards.
- Use a play pen or a gated area with a bed and a small den-like space.
- Block part of the crate with a firm panel that cannot be knocked over or chewed.
If you use a pen, think about whether the puppy is likely to toilet in it, and ask your trainer for advice on routine.
Quick pre-purchase checklist
- Expected adult length and height written down.
- Crate inside size at least adult measurements plus 5 to 10 cm.
- Divider included and secure.
- Door wide enough for the adult.
- A plan for where the crate will sit.
- Review the setting every two weeks.
Quick summary
- Buy one crate for the expected adult length and height plus 5 to 10 cm.
- Use a divider so the usable space is the puppy’s current length plus 5 to 10 cm.
- Measure every two weeks and move the divider back when the space gets tight.
- Remove the divider when the puppy fills the crate.
- A crate is a resting place; ask your vet about how long is reasonable.
- Use the Dog Crate Size Calculator with each new measurement.
Frequently asked questions
What size crate should I buy for a puppy?
Buy for the expected adult size, then use a divider while the puppy is small. Adult length and height plus 5 to 10 cm sets the crate; the divider sets the space today.
How do I know my puppy's adult size?
Ask your vet or breeder for an estimate, and for a mixed breed expect a range. A crate with a divider tolerates a wrong guess better than a fixed small crate.
How big should the space be for a young puppy?
Big enough to stand, turn and lie down, and no bigger. Add 5 to 10 cm to the puppy's length and height as measured now.
How often should I move the divider?
Measure every two weeks in the fast-growing months and move the divider whenever the usable space gets tight.
Why not give the puppy a big crate from day one?
Too much space can make house-training harder, because a puppy may use one end as a toilet and sleep at the other, and it loses the den feel.
How long can a puppy stay in a crate?
It depends on age and the individual puppy, so ask your vet or a qualified trainer. Young puppies need regular toilet breaks, company and play.
What if the crate has no divider?
Many wire crates include one. If yours does not, ask the maker for one, or block part of the crate safely with a sturdy panel that the puppy cannot chew or push over.
Sources
- AKC expert advice (owner guidance; practical rule of thumb)
- Manufacturer sizing guidance (general industry convention; brands differ)
Related calculators
- Dog Crate Size CalculatorFind the minimum crate size for your dog from two simple measurements.
- Puppy & Kitten Age CalculatorFind your puppy's or kitten's exact age in weeks, months and days from its birth date.
- Pet Measurement ConverterConvert crate, collar, harness and coat measurements between centimetres and inches.
Keep reading
- Dog Crate Size Chart: Measure, Don't GuessA dog crate size chart built from your dog's own measurements: nose-to-tail length and standing height, with 5 and 10 cm allowances in centimetres and inches.
- What Size Crate Does My Dog Need?Measure your dog's length and height, add 5 to 10 cm (2 to 4 in) and match the result to the crate maker's inside measurements. Includes examples and puppy tips.
- How Much Should I Feed My Puppy? By AgeWork out how much to feed a puppy by weight and age: the calorie factors, meals per day, a grams table, a worked example and when to switch foods.
- Wire vs Plastic vs Soft Crates: Which to BuyWire, plastic and soft-sided dog crates compared on ventilation, travel, durability, dividers and cleaning, with a decision table and a sizing check before you buy.