Foaling date and horse age calculator
Work out when a mare is due from the last cover date, and how old a horse is officially. In Australia and New Zealand every horse turns a year older on 1 August, whatever its actual foaling date. Enter the dates and see the due date with a likely range, plus official and actual age side by side.
Due date
Defaults 340 days (320–360). Your vet can confirm with a scan.Enter the last cover date.
Age
Enter a foaling date.
In Australia and New Zealand every horse turns a year older on 1 August.
Privacy: Runs in your browser. Nothing you type is stored or sent to horse.work.
This tool gives an estimate only. It is general information, not veterinary, nutrition, legal or tax advice. Every horse and every situation is different. Check with your vet, equine dentist, farrier or a registered tax agent before you act on the result.
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How to use it
- Enter the last cover date for a due date.
- Enter a foaling date for age.
- Read the due date range and the official (1 August) age.
How it's worked out
Due date ≈ 340 days after the last cover, with a range of 320–360 days (you can change these). Official age counts 1 August birthdays in the southern hemisphere.
Questions
- How long is a mare pregnant?
- Around 11 months. The tool uses 340 days with a 320–360 day range; your vet can confirm with a scan.
- Why do all horses have a 1 August birthday?
- Racing and breeding in the southern hemisphere use 1 August as the official birthday so horses born in the same season are the same age.
- Is the due date exact?
- No. Many mares foal outside the average. Watch for signs and talk to your vet.