Reading a Kitten Weight Chart: 90-120 g to 2.5 kg

A healthy kitten weighs 90 to 120 g at birth, adds about 100 g a week, and reaches 2.0 to 2.5 kg by 5 months. Plot those 3 points on a 5 g scale and a curve appears; the curve, not any single weighing, is what tells you whether the kitten is thriving. Two consecutive weeks without gain is the line where a chart stops being reassurance and becomes a reason to book a vet visit.

Birth weight: 90 to 120 g, and why 80 g is a different animal

Birth weight is the first predictor you get, and it costs one weighing. A normal kitten is 90 to 120 g, with males 5 to 10 g heavier than females in the same litter and the largest kitten up to 30 percent heavier than the smallest. Under 90 g the kitten is small for dates and needs a warmer box and feeds every 2 to 3 hours rather than every 3 to 4. Under 80 g, survival depends on incubation-level heat at 30 to 32 C and veterinary support within 24 hours. Weigh all littermates on day 0 and write the numbers in one column; you will use them for the next 20 weeks.

100 g a week, checked by arithmetic

The working rule is 10 to 15 g of gain per day in the first 4 weeks, which is 70 to 105 g per week, and 100 g per week is the number to plan around. Run it forward: 100 g at birth plus 20 weeks at 100 g is 2.1 kg at 5 months, which sits inside the 2.0 to 2.5 kg target. If your kitten is at 700 g at 6 weeks, the arithmetic says it should reach 1.1 kg at 10 weeks, 1.6 kg at 14 weeks, and 2.1 kg at 20 weeks. Any deviation of more than 15 percent from that line, in either direction, is worth a second weighing before it is worth worry.

The reference curve, week by week

The table below is the same arithmetic laid out, with the 5 g scale band that counts as on track. Male kittens and singleton litters usually run at the top of each band; females and litters of 5 or more run 10 to 20 percent below it.

Age	Expected weight	Gain that week	Gain since birth	5 g scale band
Birth (day 0)	90-120 g	-	0 g	85-125 g
Week 2	230-300 g	70-105 g	130-210 g	225-305 g
Week 4	380-480 g	70-105 g	280-390 g	375-490 g
Week 8	750-900 g	90-120 g	650-800 g	740-915 g
Week 12	1.15-1.45 kg	95-140 g	1.05-1.35 kg	1.10-1.50 kg
Week 20 (5 months)	2.0-2.5 kg	100-150 g	1.9-2.4 kg	1.95-2.55 kg

Plateau or stall: the 14 day rule

A 1 day plateau is normal and happens around vaccination, a food switch, or a hot afternoon. A 7 day plateau at 3 to 5 percent below the line is a note in the log. Two consecutive weeks with no net gain is the alert threshold, and it has a short list of causes worth checking in this order: worms (a 4 week old with a pot belly and 2 weeks of flat weight), feeding volume (a 12 week old eating 60 percent of what the chart implies), dental pain at 4 to 6 months when the premolars erupt, and chronic diarrhea at 2 or more loose stools a day. Weight loss of 5 percent in a kitten under 12 weeks is an emergency, not a plateau.

The 5 g scale protocol, same time every day

A 5 g resolution is the practical minimum; a 1 g jeweler's scale is better under 200 g. Weigh at the same hour, before the first meal, with an empty bladder, on the same folded towel, and tare the towel each time. Three readings a week is enough after 12 weeks, daily is better before. Log weight, date, and food intake in grams per day, because a kitten that gains 10 g a day while eating 40 g a day is a different case from one gaining 0 g while eating 55 g a day and having 3 loose stools.

A weighing is only comparable to the last one if the conditions match. A kitten weighed after a 12 mL feed reads 12 g heavier, and one weighed 2 hours after a vaccine reads 3 to 8 g heavy from the fluid bolus under the skin. Take 2 readings 24 hours apart before you reinterpret the curve, and use a 7 day average as the working number once the kitten passes 600 g.

Sex, litter size, and breed shift the line 10 to 20 percent

Do not read a chart as a target. Males finish 20 to 25 percent heavier than females. A litter of 6 pushes every kitten 10 to 15 percent below a litter of 2. Breed matters at the extremes: a Maine Coon can be 1.0 kg at 8 weeks and still be normal, while a Singapura at 750 g at 8 weeks is also normal. Use the curve for direction, and the kitten's own first 4 weeks as its personal baseline.

When the curve is a symptom

Call a vet the same day for any of: weight loss of 5 percent or more at any age, 3 consecutive days of loss, gain under 50 g in a week after 4 weeks of age, a body temperature below 37.5 C, 2 or more days of diarrhea, or a kitten that stops gaining while its abdomen enlarges. Bring the log, not the memory of it: 3 weeks of numbers lets a vet see a 48 hour event that a single weighing hides.

Do this for the next 7 days

1. Buy a 5 g scale and a notebook; write the birth weight and the date if you have them.
2. Weigh daily at the same hour before the first feed, towel tared.
3. Record grams eaten as well as grams gained, so the 2 can be compared.
4. Mark the week 20 target of 2.0 to 2.5 kg on the page and draw the line backward.
5. If 2 weeks pass with no net gain, call a vet and bring the log.

When the line flattens, the checks are in kitten weight stall; if appetite changes at the same time, look at the teeth eruption chart before assuming illness.

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