Kitten Weight Calculator
Is your kitten on track? Enter age in weeks and current weight — we plot you on a vertical target-weight ladder spanning birth → 1 year, with per-breed CFA rungs and a fading-kitten flag if you fall more than 20% below at week < 4.
Target-weight ladder
Expected 1150 g (range 978–1323 g). Weight gain slows after weaning, ~70–100 g per week for kittens 8–16 weeks. Switch from kitten formula to kitten food gradually starting week 4.
Reality-Check: What this ladder tells you
What "on track" means
Within ±15% of the breed-specific weekly target. Wider variance does NOT mean unhealthy — it means call the vet to investigate parasites, dental issues, or feeding-management causes.
The fading-kitten line
Below 80% at week < 4 = fading flag. This is not a "wait and see" — fading-kitten progresses in hours. Warm, hydrate with kitten milk replacer, vet visit today.
Feeding stage by rung
Birth–wk 4: queen's milk or KMR every 2–4 h. Wk 4–8: weaning to kitten food (mash). Wk 8+: kitten growth formula, 4 meals/day until 6 mo, then 3.
Kitten weight reference (g / oz / lb)
| Grams | Ounces | Pounds | Typical age |
|---|---|---|---|
| 75 | 2.65 | 0.165 | Birth (small breed: Devon Rex) |
| 100 | 3.53 | 0.220 | Birth (DSH median) |
| 110 | 3.88 | 0.243 | Birth (Maine Coon) |
| 200 | 7.05 | 0.441 | Week 1 (most breeds) |
| 320 | 11.29 | 0.705 | Week 2 (most breeds) |
| 540 | 19.05 | 1.190 | Week 4 — weaning |
| 1150 | 40.57 | 2.535 | Week 8 — homecoming |
| 1800 | 63.49 | 3.968 | Week 12 — 3 months |
| 2400 | 84.66 | 5.291 | Week 16 — 4 months |
| 3500 | 123.46 | 7.716 | Week 26 — 6 months |
| 4500 | 158.73 | 9.921 | Week 52 — 1 year (DSH adult) |
Continuous growth curves instead of rung checkpoints? Use the kitten growth chart.
Ladder math
% of expected
pct = current_g / expected_g × 100On-track 85–110%; above-average 110–120%; overweight >120%; underweight 80–85%; fading flag <80% at week <4.
Inter-rung interpolation
expected = a + (week − w_a) / (w_b − w_a) × (b − a)Linear between rungs (more accurate than a flat polynomial for short kitten windows).
Daily-gain target
daily_gain ≈ (w_next_rung − w_current_rung) / weeks × 7DSH week 0 → 4: (540 − 100) g / 4 wk / 7 d ≈ 15.7 g/day.
Predicted adult weight
adult_kg ≈ ladder.rung[52].targetG / 1000For slow-mature breeds, expect 5–15% further gain past week 52 until 36–48 months.
How to weigh and read the ladder
- 1Use a digital kitchen scale (1 g precision)Vet beam scales round to ±25 g — too coarse for kittens under 500 g. Tare a small towel on the scale, set kitten on towel, hold steady briefly.
- 2Weigh same time each dayPre-feeding gives consistent baseline. Daily through week 4, twice weekly week 4–8, weekly week 8–16.
- 3Plot age in weeks (decimals OK)5.5 weeks works — the calculator interpolates between rungs. Birthday math: (today − birth_date_ISO) / 7.
- 4Read the verdict + next rungOn-track = within ±15%. If underweight, schedule vet (parasites, dental, food). If fading-flag at < 4 wk, vet today.
- 5Save the reading and check weeklyHistory panel below stores 8 most recent readings — useful for trending across vet visits.
Saved readings
No saved readings yet.
Why a ladder, not a curve
In 2026, a kitten foster mom checking weights at 3 am on a 4-day-old runt does not need a continuous regression curve — she needs to know whether tonight's weigh-in is on the right rung. The ladder format here makes that judgment instantaneous: rung labels, ±15% bands, verdict chip in three colors.
The reference weights at each rung come from Loveridge's 1986 Waltham kitten study (the foundational dataset for feline growth), refined by CFA breed-standard weights, ICatCare nursery protocols, and AAFP-AAHA Feline Life Stage Guidelines 2021. The Loveridge data established the 10–15 g/day pre-weaning and 15–20 g/day post-weaning targets that this calculator's daily-gain insight cites directly.
Fading-kitten syndrome — the < 80% at week < 4 trigger — is the leading cause of neonatal kitten mortality. Cornell Feline Health Center estimates 15–27% of pedigreed kittens fade in the first 8 weeks of life, with mortality concentrated in week 1. The ladder's < 80% threshold is the same trigger used by feline neonatology specialists: anything below that band requires immediate warming, hydration with kitten milk replacer, and a vet visit within hours, not days.
Why ±15% rather than a tighter band? Because the published feline kitten weight data has natural variance — even within one CFA-registered litter, individual kittens can vary ±10% from the litter mean. The ±15% band gives families a credible "you're fine" answer without false alarms, while still catching the kittens who actually need intervention. Tightening the band would multiply unnecessary vet visits without improving outcomes.
The 9-rung structure (birth, weeks 1, 2, 4, 8, 12, 16, 26, 52) mirrors the standard veterinary kitten-checkup cadence — wellness visits typically happen at week 8 (first vaccines), week 12 (boosters + early spay assessment), week 16 (final FVRCP), and month 6 (spay/neuter window). Tracking on those rungs aligns owners with the exam dates their vet has already planned.
Pair this with the kitten growth chart (continuous curve view), the cat calorie calculator (matches kitten DER ≈ 2.5–3× RER), and the vaccination schedule for the 6–16 week core series.
Reviewed by feline veterinary professionals
“The ±15% rung bands make on-track easy to confirm without me on the phone. Foster moms are checking weights at the right cadence because the ladder makes it obvious which rung is next.”
“Late-rung (26 and 52 week) targets matter for slow-mature breeds. Most kitten calculators stop at 12 weeks. This one keeps going to 1 year — exactly where my breed lives.”
“Fading-kitten flag at 20% under saved a runt this March. The ladder forced me to look at the actual numbers instead of guessing.”
“The daily-gain insight in the result panel cites the exact ranges I teach — 10–15 g/day pre-weaning, 15–20 g/day post. Owners follow ranges they can verify on a kitchen scale.”
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