How big is baby?

The sources behind every size and comparison on the site.

Baby size data

DataWeeksSource
Height and weight1-2Human egg size (Cavilla et al., Human Reproduction 2008;23:37-45)
Height3-5UNSW Embryology, Carnegie Stages (O'Rahilly & Müller 1987)
Weight3-4Estimated from the embryo's size
Weight5-14Embryo weight by crown-rump length, Kyoto Collection (Nishimura et al., Teratology 1968;1:281-90)
Height6-8Robinson & Fleming crown-rump length formula (BMUS, Fetal size and dating: charts recommended for clinical obstetric practice, 2009)
Height9-14INTERGROWTH-21st crown-rump length (Papageorghiou et al., Ultrasound Obstet Gynecol 2014;44:641-8)
Height15-23Haase's rule, with the INTERGROWTH-21st length spread at 24 weeks
Height24-40INTERGROWTH-21st newborn length for gestational age
Weight15-40Hadlock et al., Radiology 1991;181:129-33, in-utero fetal weight standard
Height and weight41-118WHO Child Growth Standards (WorldHealthOrganization/anthro)

Pokemon

DataSourceLicense
Names, species, heights, weights, types, Pokedex entriesPokeAPIPokemon content © Nintendo, Creatures and Game Freak
SpritesPokeAPI sprite repositoryPokemon content © Nintendo, Creatures and Game Freak

D&D dice

DataSourceLicense
Spells, damage rolls, sneak attack diceSystem Reference Document 5.1 by Wizards of the Coast LLC, via the D&D 5e SRD APICC-BY-4.0
Die sizes"Opaque Colors Polyhedral 7-Piece RPG Dice Set" listing
Die weightsdice.co.uk

Candy

ItemsSource
Sugar grainWhatSugar (crystal size), MadSci Network (grain weight)
NonpareilRetail nonpareil listing
Nerds, boxesNerds product page
Dippin' Dots beadC&EN
Candy buttons, stripBon Appetit, CandyFavorites
US Smarties, rollWikipedia, product label
Nestle Smarties, tubeWikipedia, Nestle
M&MDonev et al., Science 2004, USDA, Wikipedia
M&M's bagUSDA FoodData Central 169583
Tic Tac, packFerrero, Tic Tac UK
PEZ, refillWikipedia
Skittle, packSnackHistory, Skittles label
Jelly BellyJelly Belly FAQ
Haribo GoldbearHaribo factsheet, 100 Years of the Goldbear
Hershey's KissLabel listing
1-inch gumballDubble Bubble finished product specification
Snickers, fun sizeWikipedia, Sporked

Electronics

ItemsSource
Via holesJLCPCB capabilities, JLCPCB via design notes
DIP pin holeKiCad footprint library
Chip resistors 01005-2512Samsung Electro-Mechanics RC series datasheet
SOT-23, TO-220Diodes Incorporated package outlines; TO-220 weight from the MCC package weight list
SOIC-8Central Semiconductor package details
TO-92Teccor outline; weight from the MCC package weight list
DIP-8, DIP-40Microchip PDIP package drawings
Through-hole resistorsYageo CFR series datasheet
LEDsLite-On 3 mm (via Jameco), Kingbright 5 mm datasheets
CrystalKyocera HC-49/US datasheet
USB-C portGCT USB4105 datasheet
Electrolytic capacitorsKYOCERA AVX REF series datasheet
Arduino Uno, MegaArduino Uno Rev3, Arduino Mega 2560 Rev3
Raspberry Pi 4Raspberry Pi mechanical drawing (size); third-party spec listing (weight)
2.5-inch SSDSamsung 870 EVO
3.5-inch hard driveSeagate IronWolf datasheet
BreadboardAdafruit product 239, MB-102 listings
ATX motherboard, rack panelATX specification, EIA-310 rack standard

Body parts

ItemsSource
Organ masses (thyroid, voice box, teeth, tongue, salivary glands, kidneys, heart, pancreas, spleen, lungs, brain, liver, skin, bone, skeleton, eyes)ICRP Publication 89, Table 2.8, adult reference values
Egg cellCavilla et al., Human Reproduction 2008;23:37-45
Fat cellHonecker et al., Int J Obes 2022, Table 2
Pancreatic isletHuang, Harrington & Stehno-Bittel, Cell Transplantation 2018, Table 1
Lung air sacOchs et al., Am J Respir Crit Care Med 2004;169:120-124
Kidney filter (glomerulus)Samuel et al., J Anat 2007;210:578-582
Fingernail growthBioNumbers BNID 109900
Ear bonesOssicular chain meta-analysis, J Clin Med Res 2016, Nigerian male ossicle study
Vocal cordsHirano et al. 1983 (88 autopsy larynges)
Eyeball lengthBekerman et al., J Ophthalmol 2014
Canine toothTamil cohort canine study, 2024
ThumbPort Harcourt thumb and foot study, 2024
Hand, footANSUR II (2012 U.S. Army anthropometric survey)
Kidney lengthStatPearls: Kidneys
Windpipe lengthStatPearls: Trachea
Heart lengthOpenStax Anatomy & Physiology 2e, 19.1
Spinal cordStatPearls: Spinal Cord Morphology
SpineInformedHealth.org: How does the spine work?
Long bones (radius, ulna, humerus, fibula, tibia, femur)Croatian cadaver long-bone study, Table 1

Birds

DataSourceLicense
Mass; beak, wing and tail lengthsAVONET (Tobias et al. 2022, Ecology Letters 25:581-597)CC BY 4.0
Egg mass; English names outside birds.csvLislevand, Figuerola & Szekely 2007 (Ecology 88:1605, Ecological Archives E088-096)
Species list; body length and wingspan rangesMicrosoft Data-Science-For-Beginners birds.csvMIT

Planets

BodiesSource
The SunNASA Sun Fact Sheet
Planets, dwarf planetsJPL Planetary Physical Parameters
MoonsJPL Planetary Satellite Physical Parameters
Asteroids, cometsJPL Small-Body Database API
Asteroid 2008 TC3Jenniskens et al. 2009, Nature 458:485
Chelyabinsk meteorPopova et al. 2013, Science 342:1069
DimorphosDaly et al. 2023, Nature 616:443, Table 1