What is chronological age?

Chronological age is the exact amount of time that has passed since someone's date of birth, expressed in years, months, and days.

What does the Y;M;D format mean?

It's a semicolon-separated way of writing age — years;months;days — commonly used on standardized assessment score sheets and in clinical documentation.

Why isn't a dog's age simply human age divided by seven?

Dogs age much faster than humans in their first two years, then more gradually afterward, and the rate varies by adult size, so a flat seven-times multiplier doesn't reflect that curve.

Until what age should I use corrected age for a premature baby?

Most pediatric guidance recommends using corrected age for developmental comparisons up to around 24 months.

Does the calculator account for leap years?

Yes. All five tools calculate from real calendar dates, so leap years and differing month lengths are handled automatically.

Can I switch languages without losing my entered dates?

Yes. Switching the language only changes the interface labels and month names — any dates you've already entered stay exactly as they are.

Does this work on mobile?

Yes. All five calculators, the language switcher, and the copy-to-clipboard button are fully usable on phones and tablets.

Free Age Calculator – Chronological Age, Age Difference, Dog Age & Corrected Age

Calculate exact age, to the day

Four precise calculators — chronological age, age difference, birthday countdown, and dog age — with a clinical Y;M;D format built in.

Date of birth

Assessment date

Defaults to today

Person A — date of birth

Person B — date of birth

Date of birth

Adult dog size

Small≤9 kg

Medium10–22 kg

Large23–40 kg

Giant40+ kg

Dog’s age (years)

Date of birth

Gestational age at birth (weeks)

Assessment date

Defaults to today

Calculate exact age, to the day

Recent calculations