A healthy newborn kitten weighs 90 to 120 g, gains 10 to 15 g a day, and loses no more than 10 percent of birth weight in the first 24 hours. Those 3 numbers catch almost every problem in the first 3 weeks, and they only work if the kitten is weighed the same way every day. There are 2 ways to do it: weigh the kitten directly on a 1 g scale, or weigh a box and subtract it, which is the version that works for a litter that will not sit still.
The birth weight band, and what falls outside it
90 to 120 g is the middle of the range for a typical litter of 4. Litter size moves it: a litter of 1 or 2 kittens often runs 110 to 140 g each, and a litter of 6 or 7 runs 75 to 95 g. Both ends are normal. What is not normal is under 75 g in any litter, a kitten 30 percent lighter than its largest littermate, or a birth weight that is not recorded at all. A kitten at 70 g has 1 percent of an adult's body fat and about 4 hours of energy reserves, so it drops faster and needs its first weight logged within 2 hours of birth.
Why the daily number is 10 to 15 g
A kitten should double birth weight by day 7 to 10 and triple it by day 21. From 90 to 120 g at birth, that means roughly 200 to 240 g at 2 weeks and 300 to 360 g at 3 weeks, or about 100 g a week. Below 7 g a day for 2 days in a row, the curve is flat, and a flat curve at 5 days is a nursing problem, a warmth problem, or an infection. Above 20 g a day for a week in 1 kitten is usually a kitten hogging 3 of the 4 teats, and it is worth checking that the smallest littermate is not being pushed off.
Method 1: weigh the kitten directly
Use a kitchen scale with a 1 g step, or a 0.1 g jeweler's scale for the first 2 weeks, on a hard counter rather than a towel or a carpet. Zero the scale with a small bowl on it, put the kitten in the bowl, and read within 3 seconds. Weigh at the same hour every day, before the first feed, in a room at 24 to 26 C, and write the number in grams, not in ounces. A 1 g scale drifts about 1 to 2 g across a 20 C temperature swing, so keep the scale in the same room and let it sit 10 minutes before the first use of the day.
Method 2: weigh a box and subtract
For a litter of 5 that will not stay in a bowl, weigh the whole nest box with the bedding first, then add 1 kitten at a time and subtract. The error is the same 1 to 2 g per weighing, so the method costs nothing in accuracy and saves 10 minutes of chasing. Do the box empty weight once at the start of each session, not once a week. A third cross-check is the queen: weigh her before and after a nursing session and the difference should be 40 to 80 g for a litter of 4, which is a fast way to confirm the litter is actually eating.
The daily targets in 1 table
| Age | Weight band | Daily gain | Weighing frequency | Call the vet if |
|---|---|---|---|---|
| Day 0 to 2 | 90 to 120 g | 0 to 5 g | Twice a day | Under 75 g, or 10 percent lost in 24 hours |
| Day 3 to 7 | 110 to 160 g | 10 to 15 g | Once a day | No gain for 36 hours |
| Day 8 to 14 | 160 to 240 g | 10 to 15 g | Once a day | Under 7 g a day for 2 days |
| Day 15 to 21 | 240 to 360 g | 12 to 18 g | Every 2 days | Weight flat for 48 hours |
| Day 22 to 28 | 360 to 480 g | 15 to 20 g | Every 2 days | Weight falling in week 4 |
The 24-hour line matters more than any other row. A kitten born at 100 g that reads 89 g on day 1 has lost 11 percent, and the answer is a vet visit that day, not a bigger bottle. A 5 percent loss at 24 hours is normal and should be recovered by day 3 or 4; a 9 percent loss that has not been recovered by day 5 is the same problem 2 days later.
What the scale sees before your eyes do
Weight loss shows up 24 to 48 hours before a kitten looks thin, and 12 to 24 hours before it stops crying for food. Dehydration at 5 to 8 percent of body weight is already visible as skin that tents when pinched at the shoulder, and a kitten at that point is usually 1 feed behind, not 1 day behind. Body temperature is the other half of the picture: 35 to 37 C in the first 24 hours is normal, and under 35 C means warm first and feed second. Any kitten that loses weight and feels cool needs a vet the same day, and a kitten that is limp or unresponsive needs the resuscitation protocol your vet has given you, not a web search at 2 a.m.
Recording it so the curve means something
One sheet per litter, 1 column per kitten, 1 row per day, and the birth weight in the first row. A 4-kitten litter over 28 days is 4 columns and 28 rows, which fits on 1 page and answers the only question that matters at day 10: is this kitten gaining, flat, or falling. Weighing is the single cheapest tool in a nursery, well under the cost of 1 emergency visit, and it is the only one that works while the kitten is asleep.
The next 7 days
- Day 1: weigh every kitten within 2 hours of birth and write the gram figure, not a range.
- Day 1: zero the scale with the bowl, on a hard counter, in the room where the litter lives.
- Day 2: weigh twice, before the first and last feed, to see the daily swing.
- Day 4: compare each kitten to its own birth weight, and to the litter average, in that order.
- Day 7: expect 110 to 160 g, and book a vet visit for any kitten under 100 g.
Track the queen alongside the litter with the weight gain log: a queen who is losing weight while 4 kittens gain 12 g a day is telling you she is not eating enough for the job. If the litter was never planned, spaying the queen at 6 months is the default, and the 4-column sheet above never has to be started.
Frequently asked
What is a normal birth weight for a kitten?
90 to 120 g for a typical litter of 4. Litters of 1 or 2 run 110 to 140 g each, and litters of 6 or 7 run 75 to 95 g, so the number only means something next to the littermates. Under 75 g, or 30 percent below the largest littermate, needs a vet within 24 hours.
How much weight should a kitten gain each day?
10 to 15 g a day for the first 2 weeks, roughly 100 g a week, which doubles birth weight by day 7 to 10 and triples it by day 21. Under 7 g a day for 2 days in a row is a flat curve, and a flat curve at day 5 is a feeding, warmth, or infection problem.
When does weight loss become an emergency?
A loss of more than 10 percent of birth weight in the first 24 hours means a vet visit that day, not a bigger bottle. A 5 percent loss at 24 hours is normal and should be recovered by day 3 or 4, so a 9 percent loss still missing on day 5 is the same problem 2 days late.