Kitten Growth Spurt: 100-150 g a Week at 4-6 Months

Between 4 and 6 months a kitten adds 100 to 150 g (3.5 to 5.3 oz) a week and needs about 2.5 times its resting energy requirement. That 8 week stretch decides adult frame size, coat density, and how much muscle the cat carries at 2 years. Weigh weekly on the same scale, write the grams down, and judge by the 3 week average instead of a single reading. Growth plates close near 8 months in most domestic cats, so the ration should drop at that line, not at 12 months.

Where the 2.5 times figure comes from

Resting energy requirement is 70 times body weight in kilograms to the power 0.75. A 2 kg kitten at 18 weeks has an RER near 118 kcal a day, and 2.5 times that is 295 kcal. Feed maintenance instead, roughly 1.2 times RER or 140 kcal, and the kitten eats to that ceiling and coasts. Kittens regulate intake less tightly than adults do, which is why a measured ration beats a topped-up bowl. Weigh the day's food once at 07:00, split it into 3 or 4 portions, and put the scoop away between meals.

The weekly gain, month by month

Age	Typical weight (kg)	Gain per week (g)	kcal per day	Meals per day
8 weeks	0.8	100 to 120	200	4
12 weeks	1.3	100 to 150	250	4
16 weeks	1.8	110 to 150	280	3
20 weeks	2.2	100 to 140	320	3
24 weeks	2.6	90 to 130	350	3
32 weeks	3.2	40 to 70	320	2

The table is a reference band, not a target to force. Read direction first: a kitten 200 g under the band that still gains 120 g a week is fine, and one sitting on the band that gains 20 g a week is not. The numbers here assume a domestic shorthair; for breed-specific ranges see the kitten growth chart, and for the calorie math by age see kitten calorie targets.

A weighing routine that gives usable numbers

Nothing in this window is measured by eye. Same scale, same time, before the first meal. A 25 dollar kitchen scale that reads to 5 g beats a bathroom scale that reads to 100 g, and a notebook beats an app you open once a week. Set the kitten in a 2 liter bowl, tare it, and log 3 fields: date, grams, and whether the cat ate in the previous 2 hours. One reading means nothing, 2 in the same direction are a hint, and 3 are a trend. A kitten that gains 100 g, then 60 g, then 140 g is normal. One that gains 120 g, 40 g, then 10 g across 19 days needs a vet visit and a fecal test, not a new food.

From kcal to grams in the bowl

Use the label's kcal per kg, never the cup scoop. Dry kitten food runs 3,800 to 4,300 kcal per kg, so 280 kcal is 65 to 74 g. Wet food at 85 kcal per 100 g needs 330 g, which is 3 to 4 pouches a day. Split into 4 meals at 07:00, 12:30, 17:30 and 21:30 below 5 months, then 3 meals from 5 to 8 months. Leave food down for 20 to 30 minutes, lift it, and write down what was left. At 4 months expect 70 g of dry or 330 g of wet; at 6 months, 85 g of dry or 410 g of wet.

The 8 month bone line

Growth plates in the radius and femur close between 7 and 9 months in most cats, and later in the big breeds: Maine Coons and Ragdolls can run to 12 or 15 months. Closing is the point where extra calories stop building bone and start building fat. Most vets move from kitten formula to adult formula between 10 and 12 months, but the ration should taper at 8 months if the cat already weighs 3.2 to 3.5 kg with no visible waist. Body condition should read 5 out of 9 for the whole spurt; 6 out of 9 at 7 months is early, not cute.

When weight gain stops before 6 months

A kitten under 6 months that gains less than 50 g a week for 2 straight weeks, or loses any weight, is a medical case. The usual causes are roundworm, coccidia, giardia, a dental or palate defect, and feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV). Book a visit the same day for a belly that looks bloated while the ribs show, pale gums, diarrhea past 48 hours, 3 or more vomits in 24 hours, or a temperature over 39.5 C. Bring the weight log; 6 numbers explain more than 6 sentences.

What changes at 6, 8 and 12 months

At 6 months cut from 4 meals to 3 and hold total kcal flat for 14 days before changing anything else. At 8 months drop to about 2 times RER, which for a 3.2 kg cat is 330 kcal. At 12 months move to adult maintenance at 1.2 to 1.4 times RER and re-check weight every 4 weeks. Dry food usually falls 20 to 30 percent between 6 and 12 months even though the cat looks the same size, and that drop is expected, not a sign of illness. Re-measure the kibble on the same scale you use for the cat, because a heaped cup drifts by 15 to 20 percent from one bag to the next. If the cat is a large breed, add 4 to 6 months to every line above; the breed quiz gives the adult size band you are aiming at.

Five steps for this week

1. Weigh the kitten tonight, before dinner, and start a log with date and grams.
2. Compute 70 times weight in kg to the power 0.75, multiply by 2.5, and compare with the table row for its age.
3. Measure the day's ration at 07:00 into 3 or 4 portions instead of refilling the bowl.
4. Re-weigh on day 7 and day 14; act on the 3 week average, not on one number.
5. Book a vet visit if the 2 week gain is under 100 g total, or if any weight is lost.

Terms mentioned in this article

FIV

Frequently asked

How much should a 4 to 6 month kitten gain each week?

Between 100 and 150 g a week, which is 3.5 to 5.3 oz, and the higher end belongs to males and to large breeds. Judge it on a 3 week average, because a vaccine, a worm treatment or a hot night can flatten one week. Two straight weeks under 50 g, or any loss, means a vet visit rather than a bigger bowl.

Do I have to stop kitten food at 8 months?

No. Eight months is when growth plates close in most cats, so it is the point to stop increasing the ration and to watch body condition, not necessarily to switch formula. Most vets change to adult food between 10 and 12 months. Large breeds such as Maine Coons can keep growing to 15 months, so they stay on kitten food longer.

Is 2.5 times RER too much food for an indoor kitten?

It is a starting figure, not a fixed dose. Compute 70 times weight in kg to the power 0.75, multiply by 2.5, then adjust every 14 days against the weight trend and a body condition score of 5 out of 9. An indoor kitten that gains 150 g a week on 2.5 times RER is eating correctly; one gaining 250 g a week is being overfed.