A first litter leaves you with no records to go on, while for an animal that has whelped before those records are the most useful information you have. This calculator starts from the size band average for the projected adult weight, and if you add past litters it reports how far your own average sits from that figure.
| Size band | Projected adult weight | Average litter |
|---|---|---|
| Toy | under 5 kg (about 11 lb) | 3.5 |
| Small | 5 to under 10 kg (11 to 22 lb) | 4.2 |
| Medium | 10 to under 25 kg (22 to 55 lb) | 5.7 |
| Large | 25 to 45 kg (55 to 99 lb) | 6.9 |
| Giant | over 45 kg (about 99 lb) | 7.1 |
The averages above are the size band figures reported by a retrospective study of 10,810 litters across 224 breeds, where the average across all breeds was 5.4. The same study reported that litter size is affected by mating method and the age of the dam as well as by body size. Cats have no table as firm as the canine one, so they are given as one range of usually 4 to 6 with an average of about 5.2. Counting fetuses during pregnancy is work your veterinarian does with ultrasound or radiographs, following AAHA and American Association of Feline Practitioners (AAFP) guidance. Guidance current as of October 2026.
A band figure is an average, so it misses the count for an individual easily. This tool uses no table of numbers by breed, and it does not calculate a due date or the risk of a difficult birth. This tool is for reference only and does not replace veterinary care. Contact your veterinarian right away if you notice symptoms or suspect a problem.
Frequently Asked Questions
Enter only the projected adult weight and the size band average comes back as a reference. It is an average though, so it misses the count for an individual easily, and during pregnancy counting fetuses on ultrasound or radiographs is more accurate.
By itself it tells you nothing. The same study reported that litter size is affected by mating method and the age of the dam as well as by body size. If it worries you, review the records with your veterinarian.
No material organizing average litter size by body size for cats, the way it exists for dogs, could be confirmed. Cats are therefore given as one range, usually 4 to 6 newborns with an average of about 5.2.