Kitten Weight Calculator — Week-by-Week Growth
Newborn kittens enter the world weighing barely 100 grams — about the weight of a chicken egg — and grow into pouncing, climbing, loaf-shaped adolescents within months. The first weeks decide a huge amount about long-term health. This calculator tracks your kitten's current weight against healthy benchmarks, flags concerning gaps, and lists the developmental milestones expected at each stage.
Kitten Weight & Growth Calculator
Enter your kitten's age and current weight to see how the numbers compare against age-appropriate healthy ranges.
Use weeks for kittens under 12 weeks. Switch to months from 3 months onward.
Grams give the most accurate result for kittens under 8 weeks.
About the reference ranges
How to Use the Kitten Weight Calculator
The whole assessment takes under two minutes once you have a kitchen scale on hand.
- 1
Weigh accurately with the right scale
Newborn kittens need gram-accurate measurements — a digital kitchen scale works perfectly. For kittens over 500 g, any pet or baby scale is fine. Weigh at the same time of day, ideally before a feed, to keep readings consistent.
- 2
Enter age and current weight
Use weeks for any kitten under 12 weeks old, where day-to-day growth is most variable. Switch to months for older kittens. The weight field accepts grams, ounces, or kilograms via the unit toggle.
- 3
Review the comparison to the healthy range
Three zones display: below healthy, within healthy, and above healthy. 'Below' isn't always a crisis — premature or runt kittens can catch up — but it warrants closer monitoring and possibly a vet check.
- 4
Log results over time and watch trends
A single low weight matters less than a downward trend across several readings. Print or save the results from each check to build a growth chart. For newborn kittens, daily measurements are non-negotiable.
Kitten Weight by Age — Healthy Range Chart
Healthy weight bands across the first year. These ranges cover average-sized domestic kittens. Large breeds like Maine Coon and Ragdoll sit at the high end of the range from birth; small breeds like Singapura sit at the low end.
| Age | Healthy weight | Imperial | Daily gain |
|---|---|---|---|
| Newborn (day 0-3) | 90–110 g | 3.2–3.9 oz | — |
| 1 week | 150–250 g | 5.3–8.8 oz | 10–15 g/day |
| 2 weeks | 250–350 g | 8.8–12.3 oz | 10–15 g/day |
| 3 weeks | 350–450 g | 12.3–15.9 oz | 10–15 g/day |
| 4 weeks | 400–500 g | 14.1–17.6 oz | 10 g/day |
| 5 weeks | 500–600 g | 17.6 oz–1.3 lb | 10 g/day |
| 6 weeks | 600–750 g | 1.3–1.7 lb | 10–15 g/day |
| 7 weeks | 750–900 g | 1.7–2.0 lb | 15 g/day |
| 8 weeks | 800–1000 g | 1.8–2.2 lb | 15 g/day |
| 10 weeks | 1.0–1.4 kg | 2.2–3.0 lb | — |
| 12 weeks (3 mo) | 1.4–1.8 kg | 3.0–4.0 lb | — |
| 16 weeks (4 mo) | 1.8–2.3 kg | 4.0–5.0 lb | — |
| 5 months | 2.3–2.7 kg | 5.0–6.0 lb | — |
| 6 months | 2.7–3.6 kg | 6.0–8.0 lb | — |
| 8 months | 3.2–4.5 kg | 7.0–10.0 lb | — |
| 10 months | 3.6–5.0 kg | 8.0–11.0 lb | — |
| 12 months | 4.0–5.5 kg | 9.0–12.0 lb | — |
Need to predict adult size? Try the Cat Breed Size Calculator for breed-specific projections.
Kitten Developmental Milestones
Physical and behavioural changes happen on a predictable timeline. Catching delays early gives the best chance of intervention.
0–7 days (Neonatal)
Eyes and ear canals closed. Cannot regulate body temperature — relies on the queen for warmth (around 35-37°C). Umbilical cord falls off by day 3. Cannot urinate or defecate without stimulation. Spends 90% of time sleeping or nursing.
8–14 days (Transitional)
Eyes open between days 7-14, all initially blue. Ear canals open around day 9-12. First wobbly attempts at walking. Birth weight should double by the end of week 2.
2–4 weeks (Socialisation start)
Walking confidently by week 3. Baby teeth (deciduous incisors) begin erupting at days 14-21. Litter box training begins instinctively at 3-4 weeks. Eye colour starts shifting from neonatal blue.
4–8 weeks (Peak socialisation)
The critical socialisation window (Karsh & Turner, 1988). Positive human contact during weeks 2-7 shapes adult temperament more than any later experience. Weaning begins around week 4. First FVRCP vaccine typically at 6-8 weeks.
8–12 weeks (Juvenile)
Fully weaned. Playing intensively, hunting and pouncing reflexes sharpen. All baby teeth in place. Most adoption rescues release kittens to new homes at 8-12 weeks. Booster vaccines and rabies typically given here.
3–6 months (Pre-adolescent)
Permanent teeth replace deciduous teeth between months 3 and 7. Spay/neuter typically performed at 4-6 months in pet kittens. Growth rate slows compared to early weeks but is still rapid.
6–12 months (Adolescent)
Sexual maturity in most breeds by 6-9 months. Growth continues but at a slower pace. Most kittens reach 80-90% of adult weight by 12 months. Switch from kitten food to adult food at 12 months for short-haired breeds, 18 months for large-breed slow-maturers.
Feeding Schedule by Kitten Age
Feeding frequency drops as kittens mature, but total daily calories stay high through the first year. The American Animal Hospital Association (AAHA) recommends free-feeding mother-raised kittens through 6 months, then transitioning to measured meals.
| Age | Food type | Frequency |
|---|---|---|
| 0-4 weeks | Queen's milk or KMR | Every 2-3 hours (bottle-fed) |
| 4-5 weeks | Wet food + KMR slurry | 4-5 times daily |
| 5-8 weeks | Wet kitten food | 4 times daily |
| 8-12 weeks | Wet + dry kitten food | 3-4 times daily |
| 3-6 months | Kitten formula | 3 times daily |
| 6-12 months | Kitten formula | 2-3 times daily |
For exact calorie targets, see the Cat Calorie Calculator — kittens use a multiplier of 2.0-2.5× their Resting Energy Requirement.
When a Kitten Needs Urgent Veterinary Care
⚠️ Don't wait if you see any of these signs:
- No weight gain — or weight loss — in a newborn kitten over 24 hours
- Cold, limp, or unresponsive kitten — possible hypothermia (a feline emergency below 35°C / 95°F body temperature)
- Refusal to nurse for more than 2-3 feeds in a newborn
- Persistent crying paired with inability to settle
- Diarrhoea lasting more than 24 hours — dehydration sets in fast in kittens
- Bloated belly, especially in bottle-fed kittens (possible overfeeding or gut problem)
- Discharge from eyes, nose, or umbilical area
- Breathing difficulty — rapid, laboured, or open-mouth
- Pale or yellow gums
- Seizures, tremors, or rapid breathing — hypoglycaemia is common in kittens under 6 weeks
Kittens deteriorate fast. What looks like a minor problem in adult cats — skipping one meal, a single loose stool — can become life-threatening in a kitten within hours.