Buy a 1 g scale before the litter arrives, weigh every kitten once a day at the same time, and treat a 5 g difference as information rather than noise. A newborn weighs 90 to 115 g, so 5 g is 4 to 5 percent of its whole body, which is why a kitchen scale that reads in 5 g steps hides the exact loss that matters. Three record sheets, a daily log, a 7-day average, and an event log, carry the whole system, and 2 bad days on the daily log are enough to call a vet.
Why 1 g and Not 5 g
The signal you are hunting is small in absolute terms. A healthy kitten gains 7 to 14 g a day in the first 3 weeks, and a kitten going wrong loses 5 to 10 g a day for 2 days before it stops nursing. A 5 g resolution scale reports both events as the same number, or as nothing at all. A 1 g kitchen scale costs less than 1 bag of premium kitten food and is accurate to about 1 g up to 5 kg, which covers a kitten from birth to 16 weeks. For a litter under 150 g at birth, a 0.1 g jeweler's scale is better, because at that size 1 g is already 1 percent.
Two practical details decide accuracy more than the price. Put the scale on a hard floor or a stone counter, never on carpet, and zero it with the same towel or basket each time. A towel that weighs 40 g and gets swapped for one weighing 55 g silently adds 15 g to every reading, which is 3 days of growth.
The Daily Routine in 90 Seconds
Weigh at the same hour every day, before the first feed, after the kitten has been stimulated to urinate. Warm your hands first, because a cold hand makes a 100 g kitten squirm and the reading jumps 10 g. Set the kitten down, wait 2 seconds for the display to settle, and read it twice. Then put the kitten back with the litter, total handling under 90 seconds. At week 1 to 3 the whole litter of 5 takes under 8 minutes.
Same time matters more than same scale at this age, because a kitten that has just nursed can weigh 8 to 12 g more than it did 40 minutes earlier. Weigh at 7 am every day and the curve is comparable; weigh whenever you remember and daily change becomes unreadable.
The 5 g Line
The 5 g line cuts both ways. A single-day drop of 5 g or more in a kitten over 3 days old is a flag the same day. Two consecutive days with a gain under 5 g is a flag as well, because that is under half the expected minimum of 10 g. Neither flag is a diagnosis; both mean weigh again in 12 hours, check temperature, and look at the last 2 stools.
| Age | Target weight, 100 g birth | Minimum gain per day | Gain as percent of body weight |
|---|---|---|---|
| Day 1 to 2 | 90 to 100 g | 0 g, loss up to 10 percent allowed | 0 to 10 percent |
| Day 3 to 7 | 100 to 190 g | 10 g | 10 to 12 percent |
| Day 8 to 14 | 190 to 260 g | 10 g | 4 to 6 percent |
| Day 15 to 21 | 260 to 330 g | 8 g | 3 percent |
| Day 22 to 35 | 330 to 500 g | 10 g | 2 to 3 percent |
| Day 36 to 56 | 500 to 800 g | 12 g | 2 percent |
Read the third column as the real rule and the second as the arithmetic. A 300 g kitten gaining 8 g a day is adding 2.7 percent, which is normal. A 120 g kitten gaining 8 g a day is adding 6.7 percent, which is normal too. A 300 g kitten gaining 5 g a day is adding 1.6 percent, which is not, and the 5 g line catches exactly that.
Three Record Sheets
Sheet 1 is the daily log: one row per kitten per day, 4 columns, date, weight in grams, gain since yesterday, and who weighed it. Five kittens over 8 weeks is 280 rows, which is why it lives on a clipboard by the nest, not in a phone.
Sheet 2 is the 7-day average: one row per kitten per week, and 2 columns that matter, weekly gain in grams and weekly gain as a percent of the week's starting weight. This sheet is what you show a vet, because it removes the daily noise of a full bladder.
Sheet 3 is the event log: feeding changes, stool changes, temperature, any treatment, any vet visit, with a date and an hour. When a kitten flags on sheet 1, sheet 3 is what tells you whether the cause was a food switch 3 days ago or a dose 2 days ago.
Reading a Curve, Not a Number
A kitten should double its birth weight by day 7 to 10 and triple it by day 21. If a kitten is at 1.6 times birth weight on day 10, the curve is behind, even if today's number looks fine next to yesterday's.
Percent gain also has an upper end. Sustained gain above 20 g a day in the first 2 weeks, or a kitten that is 25 percent heavier than its littermates by day 14, is worth a vet look, because a single kitten nursing the front teats can overeat while the runts lose ground.
Warmth and Handling Before You Weigh
Never weigh a cold kitten to get a number, warm it first. A kitten under 35 C cannot digest food and should be warmed at 1 C per 20 to 30 minutes toward 37 C before anything else happens. Keep the room at 24 to 27 C in week 1, and handle each kitten for under 90 seconds at a time, the same short-block logic that works for early handling from day 3 to 16, described in the kitten handling window. Weighing is also the cheapest way to tell males from females early, since the distance check at 3 weeks is 1 cm against 2.5 cm, covered in kitten sex identification.
When a Number Becomes a Vet Call
Call the same day for a drop of 10 percent or more of birth weight inside 24 hours, 3 consecutive days under the 5 g line, no gain across 48 hours in week 1, a temperature under 37.5 C or over 39.5 C, or a kitten that has stopped latching. Bring sheet 1 and sheet 2, not a verbal summary, because a vet reads 7 numbers in 20 seconds and a story in 2 minutes. What the whole setup costs, scale included, is in the cost tools.
Five Steps for Tonight
- Buy a 1 g scale with a 5 kg capacity and a tare button before the due date, not after.
- Print 3 sheets and clip them by the nest, daily log, 7-day average, event log.
- Fix the weighing hour, before the first feed, and write it at the top of the daily log.
- Mark the 5 g line on the daily log so a flag is visible without arithmetic.
- Photograph sheet 1 every Sunday, so 8 weeks of data survive a spilled bottle.
Frequently asked
Is a kitchen scale accurate enough for a newborn kitten?
A 1 g kitchen scale with a 5 kg capacity is accurate to about 1 g and works from day 1, which is 4 to 5 percent of a 100 g newborn. It is not enough for a kitten under 150 g where 1 g is already 1 percent, so use a 0.1 g jeweler's scale for the smallest newborns, and always put the scale on a hard surface with the same towel for tare.
Do I have to weigh at the same time every day?
Yes, within about 30 minutes. A kitten that has just nursed can be 8 to 12 g heavier than 40 minutes earlier, and that swing is the same size as a real warning at week 1. Pick an hour before the first feed, write it at the top of the daily log, and weigh every kitten in the same order so handling time stays under 90 seconds each.
What counts as a real problem on the daily log?
Three patterns: a single day with a drop of 5 g or more after day 3, 2 consecutive days gaining under 5 g, or a loss of 10 percent or more of birth weight within 24 hours. Any of the three means reweigh in 12 hours, check temperature and the last 2 stools, and call the vet if the second reading confirms it.