Rat Age Converter

Convert rat age to human-equivalent age using Sengupta (2013) piecewise scaling. Strain-specific lifespan factors for Sprague-Dawley, Wistar, Fischer 344, and more.

Rat Colony ManagementAging & LifecycleClient-Side
Tool details, related tools, and citation

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Load example rat age converter data to see the full workflow

Need cross-species comparison? Try the universal Animal Age Converter

Rat Age

Conversion

Rat age
84 d
12.0 wk · 2.8 mo
Human-equivalent
14.5 human years
Sengupta (2013)
Life stage
Young adult (6 wk–6 mo)
Strain Sprague-Dawley
Lifespan position
9%
of strain median

Position on Strain Lifespan

NeonatalPre-weaningJuvenileYoung adultMature adultMiddle-agedSenescentMedian
  • Labeling rat cohort age in human-equivalent terms for translational papers
  • Choosing the right developmental window for juvenile or adolescent rat studies
  • Comparing aging-study cohorts across labs using different strain conventions
  • Justifying cohort age in IACUC and grant applications for rat studies
  • Communicating rat cohort age to clinical collaborators

Don't use for

  • As a biological-age estimate — use epigenetic clocks for that
  • For genetically-modified strains with altered lifespan (e.g. Zucker obese rats)
  • For non-rat species — use the Lab Animal Age Converter for mouse or zebrafish

Sengupta (2013) Rat-Human Age Scaling

The piecewise model used by the calculator:

  • Days 1–21 (pre-weaning): ~87 human days per rat day
  • Days 21–42 (juvenile, weeks 3–6): ~139 human days per rat day
  • Days 42–182 (young adult, 6 wk–6 mo): ~13 human days per rat day
  • Days 182–365 (mature adult, 6–12 mo): ~24 human days per rat day
  • Days 365–730 (middle-aged, 12–24 mo): ~30 human days per rat day
  • Days >730 (senescent): ~25 human days per rat day

Key anchor points: rat 6 weeks ≈ human 13 years (puberty), rat 6 months ≈ human 18 years, rat 12 months ≈ human 30 years, rat 24 months ≈ human 60 years.

Rat Aging in Translational Studies

Rats are the preferred model over mice for many aging studies because of their larger brain size, more complex behavior, and better pharmacokinetic modeling. The NIA Aged Rodent Colony provides Fischer 344 and Brown Norway rats at standardized ages.

Recommended aging cohorts:

  • Young adult: 3–6 months (~18–20 human years)
  • Middle-aged: 12–18 months (~30–45 human years)
  • Aged: 24–30 months (~60–75 human years)

Frequently Asked Questions