Mare Gestation Calculator: Horse Pregnancy Due Date

Your details

The date the mare was bred or the last successful cover date.
Breed sets the typical gestation length used in the calculation. Choose "Custom" to type your own length below.
Estimated foaling dateSecond trimester
January 29, 2027

Breeding date plus the gestation length

Earliest expected foalingJanuary 19, 2027
Latest expected foalingFebruary 8, 2027
Days pregnant so far200days
Days until due date140days
Current trimesterTrimester 2
Pregnancy complete58.8%
Gestation length used340days
58.8% %
Trimester 1<33.3%Trimester 233.3%-66.7%Trimester 366.7%+

Estimated foaling date: January 29, 2027.

  • Most mares foal anywhere from 330 to 350 days after breeding, so monitor closely from January 19, 2027.
  • The second trimester (days 114 to 227) is a period of steady growth. Maintain good body condition score (5-6 out of 9) and confirm the EHV-1 booster schedule.
  • Your horse has approximately 140 days remaining. Individual mares can vary by 20+ days, so rely on physical signs as much as calendar math.

Next stepConsult your equine vet to confirm pregnancy by ultrasound and to tailor the vaccination and nutrition schedule to your mare.

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