🌡️ Cat Heat Cycle Calculator

Your Cat's Estimated Cycle Stages

How the Cat Heat Cycle Works

Female cats (called queens) are seasonally polyestrous — meaning they cycle repeatedly throughout the breeding season rather than having a single heat per year. In the Northern Hemisphere, breeding season typically runs from February through October, driven by daylight hours. Indoor cats exposed to consistent artificial light may cycle year-round with no seasonal pause.

One key difference from dogs: cats are induced ovulators. They only release eggs if mating occurs — without mating, a cat will return to heat within 1–3 weeks rather than progressing through a post-ovulation phase. This means an unspayed cat can go into heat dozens of times per year if she never mates.

The Four Stages of the Feline Estrous Cycle

Proestrus (1–2 days): A brief lead-in phase. Estrogen begins rising. Your cat may become slightly more affectionate or vocal. Male cats may show interest, but she is not yet receptive to mating. Most owners don't notice this phase because it's subtle and short.

Estrus (3–14 days, average ~7 days): The active heat phase. This is when the dramatic behavioral changes appear — loud yowling, rolling on the floor, raising the hindquarters when touched along the back ("lordosis"), increased affection, and attempts to escape outdoors. The cat is fully receptive to mating during this window. Ovulation only occurs if mating takes place.

Interestrus (1–3 weeks): If the cat did not mate, she enters a quiet phase between heat cycles. Hormones drop, behavior returns to normal, and then the cycle restarts. This is the gap this calculator uses to estimate the next heat start date.

Anestrus: The seasonal rest phase. For outdoor cats, this typically occurs in late fall through early winter as daylight hours shorten. Indoor cats under artificial lighting may skip anestrus entirely and cycle continuously throughout the year.

Signs Your Cat Is in Heat

• Loud, persistent yowling or crying — often at night
• Rolling on the floor repeatedly
• Raising the hindquarters and treading with back feet when touched near the back or tail
• Increased affection and rubbing against people or furniture
• Restlessness, pacing, or attempts to escape outdoors
• Loss of appetite (some cats)
• Excessive grooming of the genital area

Note: cats do not typically bleed during heat. If you notice vaginal bleeding, contact your vet — it is not a normal sign of estrus in cats.

How to Manage Heat If You're Not Breeding

The only permanent solution is spaying. Cats spayed before their first heat have a significantly lower risk of mammary cancer and are not at risk for pyometra (a life-threatening uterine infection that is common in older intact females). Most vets recommend spaying at or before 6 months of age, before the first heat cycle begins.

If your cat is currently in heat and not yet spayed, keep her strictly indoors — even brief outdoor access can result in unplanned pregnancy. A single mating can be sufficient for conception. Cats can also become pregnant on their very first heat cycle, so waiting for "the right time" carries real risk.

Short-term strategies to reduce heat behavior — extra play sessions, a heating pad, calming pheromone diffusers — can help manage discomfort, but they will not stop the cycle or prevent pregnancy if she encounters a male.

At What Age Do Cats First Go Into Heat?

Most cats experience their first heat between 5 and 9 months of age, though some breeds — particularly Siamese and other Oriental breeds — can cycle as early as 4 months. The first heat is triggered by reaching a certain body weight combined with seasonal daylight cues.

Because the first heat can happen before 6 months — earlier than many owners expect — early spay appointments are important if you're not planning to breed. A cat can become pregnant on her very first heat, even as a kitten herself.