Koi age in human years

Enter your Koi's age in the calculator above. We use a science-based formula for aquatics — not the old "multiply by seven" rule — and show life stage and lifespan context with your result.

Kois are often cited as living around 40 years on average. Individual animals vary with diet, genetics, and care.

Pick Koi (already selected here), enter age in years or use date of birth when available, then calculate. You'll see human-year equivalent, life stage, and how far through a typical lifespan your pet may be.