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Pet Birthday Calculator

Find your pet's next birthday, how many days away it is and how old it will turn.

✔ Reviewed by a licensed veterinarianContent updated 18 Oct 2026Reviewed 18 Oct 2026Sources: Pure arithmetic / unit conversion on user inputs
Pet Birthday CalculatorFree · instant
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Calculated in your browser. The numbers you type are never sent to us or stored.

Quick answer. A pet born on 15 March 2020 turns 7 on 15 March 2027, which is 148 days after 18 October 2026. Enter your pet's birth date to see its next birthday, how many days away it is and how old it will be, so you can plan a treat.

How to use the pet birthday calculator

  1. Enter your pet's birth date.
  2. Optional: pick another date to count from.
  3. Press Calculate.

Worked example

A pet born on 15 March 2020, checked on 18 October 2026.

Birth date
2020-03-15
On this date (leave empty for today)
2026-10-18
148 days to go
Next birthday
15 Mar 2027
Turning
7
Days until
148

A 29 February birthday is celebrated on 28 February in non-leap years.

Example values are illustrative; this result is produced by the same calculator above.

How we calculate it

next birthday = the birth date's month and day in this or next year (29 Feb is celebrated on 28 Feb in non-leap years); days until = next birthday − today

Sources: Pure arithmetic / unit conversion on user inputs (no external constant)

Understanding your result

Enter your pet's birth date and the calculator finds its next birthday: the same month and day in this year, or next year if it has passed. It shows the date, how many days away it is and how old your pet will be.

A pet born on 15 March 2020 turns 7 on 15 March 2027, which is 148 days after 18 October 2026. If today is the birthday, it says so.

A 29 February birthday is celebrated on 28 February in years that are not leap years. If you only know an estimated age, use an estimated birth date from your vet or rescue.

Common mistakes

  • Using the adoption date instead of the birth date.
  • Typing the month and day the wrong way round.
  • Forgetting that estimated dates are approximate.
  • Expecting leap-day birthdays to fall on 29 February every year.
  • Counting the birthday day itself as part of the days to go.

Good to know

  • Birthdays are a good reminder for a vet check-up.
  • Use the Dog or Cat Age from Birth Date Calculator for human years.
  • Keep the birth date with your pet's records.

Frequently asked questions

How do I work out my pet's next birthday?

Take the birth date's month and day in this year, or next year if it has passed, and count the days from today. The calculator does it for you.

What if my pet's birthday is 29 February?

In years that are not leap years the calculator uses 28 February.

What if I only know the estimated age?

Use an estimated birth date from your vet or rescue. Many shelters pick a birthday for pets of uncertain age.

Can I count from another date?

Yes. Pick a date in the second box. Leave it empty to use today.

What if the birthday is today?

The calculator says so and shows the age your pet turns.

Does it work for any animal?

Yes. It only uses the birth date.

Reviewed by a licensed veterinarian
Last reviewed 18 Oct 2026 · How we review

Sources

  1. Pure arithmetic / unit conversion on user inputs (no external constant)

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Estimates only. Every pet is different — confirm with your veterinarian.