# Dog Age Calculator: Dog and Cat Years in Human Years

Convert your dog's age to human years using the AVMA size-based chart, or your cat's using the AAHA/AAFP chart, with life stages and the full table.

Interactive tool: https://lookup.sg/tools/dog-age-calculator

## How this works
Dogs age fastest at the start: the first year of a medium-sized dog's life is about 15 human years, the second adds about 9, and each year after that adds about 4 to 5. From around age 5, bigger dogs age faster, so this calculator uses the size-based dog years chart published by the American Veterinary Medical Association, with sizes of up to 9 kg (small), 9 to 23 kg (medium), 23 to 45 kg (large) and over 45 kg (giant). Ages between whole years are interpolated.

Cats follow the AAFP/AAHA feline life stage chart: 6 months is about 10 human years, 1 year is 15, 2 years is 24, and every year after that adds 4. The 2021 AAHA/AAFP guidelines group cats into kitten (up to 1 year), young adult (1 to 6), mature adult (7 to 10) and senior (over 10).

These are rough equivalents for comparing life stages, not a medical age. Breed, weight and health all change how a pet ages, so check-up and diet plans should come from your vet.

## FAQs
### How old is a 5-year-old dog in human years?
A 5-year-old small, medium or large dog is about 36 in human years, and a giant breed is about 45, on the AVMA chart.

### Is one dog year really seven human years?
No. A dog's first year is about 15 human years and the second about 9 more. After that each year is roughly 4 for small dogs, 4 to 5 for medium dogs, 5 to 6 for large dogs and about 7 for giant breeds, so a 10-year-old large dog is about 66, not 70.

### How old is a 10-year-old cat in human years?
A 10-year-old cat is about 56 in human years, at the end of the mature adult stage. Cats over 10 are classed as seniors, and a 15-year-old cat is about 76.

### What size dog can I keep in an HDB flat?
HDB allows one dog per flat, from the AVS list of approved small breeds (or a cross of two approved breeds), and most of those fall in the small band of this chart. AVS's Project ADORE also lets some larger mixed-breed dogs be adopted into HDB flats.

## Sources
- [AVMA: Senior pets (dog years chart)](https://www.avma.org/resources-tools/pet-owners/petcare/senior-pets)
- [AAHA/AAFP: Feline life stage guidelines](https://catvets.com/life-stage)
- [HDB: Keeping pets in HDB flats](https://www.hdb.gov.sg/cs/infoweb/community/caring-for-your-neighbours/being-a-good-neighbour/tips-on-neighbourliness/keeping-pets)

---
Source: Lookup (https://lookup.sg) · Data as of October 2026 · Listings compiled from Singapore government open data (data.gov.sg), OneMap and Overture Maps places. Free listings never show contact details; contact details appear only on Lookup Verified listings.