Convert animal age to human-equivalent age across mouse, rat, and zebrafish. Cross-species comparison, bidirectional conversion, strain-specific lifespan factors, and life-stage classification.
Try it out
Load example animal age converter data to see the full workflow
Equivalent biological age across all species (anchored to 28 human years)
| Species | Strain | Age (days) | Age (months) | Life Stage | Lifespan % |
|---|---|---|---|---|---|
| Mouse(input) | C57BL/6J | 126 | 4.1 | Young adult (6 wk–6 mo) | 16% |
| Rat | Sprague-Dawley | 328 | 10.8 | Mature adult (6–12 mo) | 36% |
| Zebrafish | AB | 311 | 10.2 | Young adult (3–12 mo) | 24% |
When to use
Do not use for
Each species model is calibrated against published developmental milestones. The comparison is most reliable at well-studied anchor points (puberty, sexual maturity, middle age) and less reliable at extremes.
A 12-month BALB/c mouse and a 12-month C57BL/6J mouse get the same human-equivalent age. The strain factor only adjusts where each sits on its own lifespan curve.
Zebrafish development is temperature-dependent. The hpf-to-days conversion assumes standard conditions (28.5°C). Lower temperatures slow development; higher temperatures accelerate it.
Animal → human → animal conversions return the original value because all scaling models are piecewise-linear and analytically invertible.
Each species uses a piecewise-linear function mapping animal-days to human-equivalent days. The function is defined by segments with different ratios reflecting developmental phases (rapid juvenile growth → slower adult aging). Reverse conversion analytically inverts the piecewise function. Cross-species comparison converts to human-equivalent years as a common denominator, then back-calculates to each species.
Last validated 2026-04-09. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.
ConductScience Lab Animal Age Converter (v0.87.0). ConductScience, Inc. 2026. Available at: https://conductscience.com/tools/animal-age-converter
Dutta S, Sengupta P. Men and mice: Relating their ages. Life Sciences. 2016;152:244-248.
Sengupta P. The Laboratory Rat: Relating Its Age With Human's. Int J Prev Med. 2013;4(6):624-630.
Kishi S et al. The zebrafish as a vertebrate model of functional aging. Exp Gerontol. 2003;38(7):777-786.
Multi-model aging studies are increasingly common, but comparing cohorts across species requires standardized age equivalence. A "middle-aged" mouse (12 months) is not the same biological age as a "middle-aged" rat (12 months) or zebrafish (18 months).
This calculator provides a common denominator — human-equivalent age — so you can design comparable cohorts across species. Enter your age in any species and see the equivalent in all others.
Stop manually labeling cohort ages. ConductColony tracks each cage's DOB and tags life-stage transitions automatically.
Open app EquipmentVentilated racks, breeding cages, and aging colony systems for rodent and aquatic facilities
Browse QuoteGet a quote on equipment or talk to the ConductScience team.
Request quote