Table 1.

Estimated parallel ages^* between the rat, associated developmental stage, and the human equivalent (Adapted from Bell et al., 2013)

Rat Ages [Post-Natal Days (PNDs)]
PNDs 1–7	PNDs 8–21	PND 21	PNDs 22–27	PNDs 28–42	PNDs 43–60	PNDs 61–75	PNDs 76–90	PNDs 90–
Male 6–15 g	16–40 g	40 g	40–70 g	70–155 g	155–260 g	260–335 g	335–390 g	390–
Female 6–15 g	16–38 g	38 g	38–65 g	65–130 g	130–180 g	180–210 g	210–250 g	250–
Human Ages
Neonate	Prejuvenile	Weaning	Juvenile	Adolescent	Peri-Adolescent	Early Young Adult	Young Adult	Adult
−3 to 0 Months	0–6 Years	6 Years	7–12 Years	13–18 Years	18–21 Years	21–24 Years	25–28 Years	28 Years–

^*Because most rat studies do not list age but many do provide body weights, estimated rat body weights (average estimates for Wistar, Long-Evans Hooded and Sprague-Dawley rats) are included here.