Can I Give My Cat Tums?

Yes, with care
Calcium carbonate is commonly referenced for cats at published doses. Published guidance for cats: 125-250 mg per cat, every 12-24h. Rarely indicated; vomiting cats need a vet, not antacids.
Source: Veterinary Partner (VIN)
Get the exact range for your cat's weight

Skip it or ask a vet first if

xylitol-sweetened versionskidney diseasewith tetracyclines

The safe habit

Confirm any medication decision with your veterinarian, who knows your cat's health history and other medications. VetDose shows published reference data, not prescriptions.

See also

Other antacid / GI questions for cats