Baby Size by Week in Animals – Interactive Week Selector
See how big your baby is each week of pregnancy compared to animals: pick a week or enter your due date, with length, weight and trimester. Free, in your browser.
How big is your baby this week? Pick a week (or enter your due date) and see the animal your baby matches — with length and weight.
We calculate your current pregnancy week from your due date. The date stays on your device.
Week 20
Your baby is about the size of…
A prairie dog
Length
25.7 cm
Weight
331 g
Trimester
2
See your baby in 3D and get the daily animal comparison in the free HiMommy app.
All weeks at a glance
- Week 4: A protozoan (0.39 cm)
- Week 5: A fruit fly (0.79 cm)
- Week 6: An ant (1.04 cm)
- Week 7: A ladybug (1.27 cm)
- Week 8: A baby snail (1.57 cm, 20 g)
- Week 9: A large bumblebee (2.3 cm, 27 g)
- Week 10: A small butterfly (3.1 cm, 35 g)
- Week 11: A tree frog (4.1 cm, 45 g)
- Week 12: A sparrow (5.4 cm, 58 g)
- Week 13: A kiwi bird (9.2 cm, 68 g)
- Week 14: A hamster (14.7 cm, 93 g)
- Week 15: A pygmy hedgehog (13.3 cm, 100 g)
- Week 16: A sugar glider (18.6 cm, 146 g)
- Week 17: A chipmunk (20.4 cm, 181 g)
- Week 18: A squirrel (22.2 cm, 223 g)
- Week 19: A guinea pig (24 cm, 273 g)
- Week 20: A prairie dog (25.7 cm, 331 g)
- Week 21: A hedgehog (27.4 cm, 399 g)
- Week 22: A rabbit (29 cm, 478 g)
- Week 23: A ferret (30.6 cm, 568 g)
- Week 24: A red fox cub (35.6 cm, 1.30 kg)
- Week 25: A chinchilla (33.7 cm, 785 g)
- Week 26: A prairie chicken (35.1 cm, 913 g)
- Week 27: A small penguin (36.6 cm, 1.05 kg)
- Week 28: A koala joey (37.6 cm, 1.21 kg)
- Week 29: A platypus (39.3 cm, 1.38 kg)
- Week 30: A fennec fox (40.5 cm, 1.56 kg)
- Week 31: A small otter (41.8 cm, 1.75 kg)
- Week 32: A small raccoon (43 cm, 1.95 kg)
- Week 33: A little red panda (44.1 cm, 2.16 kg)
- Week 34: A baby kangaroo (48 cm, 2.75 kg)
- Week 35: A dwarf rabbit (46.3 cm, 2.60 kg)
- Week 36: A small housecat (47.3 cm, 2.81 kg)
- Week 37: A small armadillo (48.3 cm, 3.03 kg)
- Week 38: A squirrel monkey (49.3 cm, 3.24 kg)
- Week 39: A large housecat (50.1 cm, 3.44 kg)
- Week 40: A newborn seal (52 cm, 3.80 kg)
- Week 41: A small beaver (51.8 cm, 3.79 kg)
See baby development week by week →
The information provided is for educational purposes only and is not intended as medical advice. Always consult a qualified healthcare provider for diagnosis and treatment.