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How big is the brain, and each part in it

On the one adult brain model this site is built on, the whole brain fits in a box about 180 mm front to back, 141 mm side to side and 166 mm top to bottom [1]. A typical adult brain weighs about 1.2–1.4 kg [2].

The hippocampus lit in red on a 3D model of the brain, seen from the front left and above

Loading the 3D brain…

Lit: the hippocampus, about 43 × 20 × 22 mm. Tap “Light it” on any row.

Slice

Drag to turn, pinch or scroll to zoom, tap any part to name it. A small part deep inside shows best with a slice: try Side or Front after lighting it.

Each “Light it” button lights exactly what that part’s own page lights, and the caption under the brain gives its box in millimetres: length (front to back) × width (side to side) × height (top to bottom).

77 parts, one ruler

Every size on this page is measured the same way on the same model. Tap “Light it” on a row, or a part on the brain, to name it.

The whole brain

Length, front to back: 180 mm
Width, side to side: 141 mm
Height, top to bottom: 166 mm

Measured from the BodyParts3D model, one adult: the box that the frontal lobe, parietal lobe, temporal lobe, occipital lobe, insula, white matter, cerebellum and brainstem fit in together [1]. The height runs from the top of the cerebrum to the bottom of the medulla, where the spinal cord begins.

A typical adult brain

The adult human brain weighs on average about 1.2–1.4 kg (2.6–3.1 lb) which is about 2% of the total body weight, with a volume of around 1260 cm³ in men and 1130 cm³ in women. [2]
There is substantial individual variation, with the standard reference range for men being 1,180–1,620 g (2.60–3.57 lb) and for women 1,030–1,400 g (2.27–3.09 lb). [2]

Size and ability: The size of the brain and a person's intelligence are not strongly related. Studies tend to indicate small to moderate correlations (averaging around 0.3 to 0.4) between brain volume and IQ. [2]

Every part with a shape, largest first

Measured from the BodyParts3D model, one adult. Each row is the box the part fits in, in millimetres, exactly as its own page gives it: length front to back, width side to side, height top to bottom. The bar under each name is its longest side against the whole brain’s 180 mm.

Sort

Brain parts by size in millimetres, measured from the BodyParts3D model, one adult. Sorted largest first.
Part	Length mm	Width mm	Height mm
Cerebrum all its parts together, both sides	180	141	117
Forebrain all its parts together, both sides	180	141	117
White matter white matter of both hemispheres with the corpus callosum	163	125	100
Inferior parietal lobule all its parts together, both sides	74	139	64
Frontal lobe the left one; the right is its mirror image	130	63	97
Prefrontal cortex the left one; the right is its mirror image	116	61	97
Superior frontal gyrus the left one; the right is its mirror image	116	32	78
Temporal lobe the left one; the right is its mirror image	114	61	60
Limbic system all its parts together, both sides	111	75	76
Cingulate gyrus the left one; the right is its mirror image	111	28	67
Middle temporal gyrus the left one; the right is its mirror image	111	36	34
Ventricles of the brain all its parts together, both sides	109	78	88
Lateral ventricles the left one; the right is its mirror image	109	39	49
Hindbrain all its parts together	85	106	76
Cerebellum	56	106	53
Superior temporal gyrus the left one; the right is its mirror image	106	43	49
Inferior temporal gyrus the left one; the right is its mirror image	96	44	29
Parietal lobe the left one; the right is its mirror image	94	69	84
Corpus callosum	92	51	39
Tentorium cerebelli right half of the tentorium cerebelli (the only half the atlas ships)	87	60	33
Middle frontal gyrus the left one; the right is its mirror image	85	35	62
Brainstem	46	42	81
Trochlear nerve the left one; the right is its mirror image	79	9	12
Basal ganglia all its parts together, both sides	64	70	37
Postcentral gyrus the left one; the right is its mirror image	64	67	60
Superior parietal lobule the left one; the right is its mirror image	57	36	67
Orbitofrontal cortex the left one; the right is its mirror image	67	40	30
Precentral gyrus the left one; the right is its mirror image	66	62	66
Caudate nucleus the left one; the right is its mirror image	64	32	37
Occipital lobe the left one; the right is its mirror image	63	44	54
Inferior frontal gyrus the left one; the right is its mirror image	63	35	60
Angular gyrus the left one; the right is its mirror image	46	43	63
Septum (septum of telencephalon)	62	20	23
Fusiform gyrus the left one; the right is its mirror image	61	32	27
Internal capsule the left one; the right is its mirror image	54	23	33
Insula the left one; the right is its mirror image	52	19	35
Diencephalon all its parts together, both sides	51	48	34
Optic nerve the left one; the right is its mirror image	49	32	22
Commissure of the fornix	31	49	20
Parahippocampal gyrus the left one; the right is its mirror image	49	21	22
Extraocular muscles the left one; the right is its mirror image	47	32	31
Supramarginal gyrus the left one; the right is its mirror image	38	46	42
Fornix the left one; the right is its mirror image	45	31	32
Epithalamus all its parts together, both sides	44	15	21
Choroid plexus the left one; the right is its mirror image	43	37	34
Stria terminalis the left one; the right is its mirror image	43	25	31
Putamen the left one; the right is its mirror image	43	18	26
Hippocampus the left one; the right is its mirror image	43	20	22
Pons	34	42	29
Medulla oblongata	33	27	41
Third ventricle	40	8	23
Fourth ventricle	23	28	38
Optic tract the left one; the right is its mirror image	38	25	8
Thalamus the left one; the right is its mirror image	37	24	24
Stria medullaris the left one; the right is its mirror image	37	4	16
Oculomotor nerve the left one; the right is its mirror image	36	25	30
Spinal cord	13	2	36
Midbrain	29	29	17
Globus pallidus the left one; the right is its mirror image	29	17	17
Eyeball the left one; the right is its mirror image	25	26	26
Anterior commissure	5	24	3
Cerebral peduncles the left one; the right is its mirror image	23	19	17
Hypothalamus	18	17	20
Amygdala the left one; the right is its mirror image	18	17	13
Cerebral aqueduct	7	3	18
Optic chiasm	10	15	8
Posterior commissure	5	15	3
Pituitary gland	10	12	13
Interventricular foramina one shape the atlas draws for both interventricular foramina	5	13	11
Lamina terminalis lamina terminalis (both halves the atlas draws)	7	3	12
Lateral geniculate body the left one; the right is its mirror image	11	8	7
Pineal gland	11	6	8
Inferior colliculus the left one; the right is its mirror image	8	8	8
Medial geniculate body the left one; the right is its mirror image	7	7	8
Superior colliculus the left one; the right is its mirror image	6	8	6
Habenula	5	8	4
Mammillary bodies the left one; the right is its mirror image	5	4	5

How to read these numbers

One ruler. Every row is measured the same way on the same model: the smallest box, lined up with the head’s front–back, side–side and up–down axes, that holds every point of the part’s surface, rounded to the millimetre. So rows compare fairly with each other: on this model the cerebrum is 4.2 times as long, on its longest side, as the hippocampus, and the mammillary bodies is the smallest row at 5 × 4 × 5 mm.
A box, not a volume. A curved, slanted or branching part fills only some of its box: the fornix arches up and over the thalamus, so its box holds a lot of space that is not fornix. Length × width × height therefore overstates any part’s volume, and this page gives no volumes because it does not check that the model’s surfaces are closed, which a volume needs.
Paired parts are measured by their left copy; the right one is its mirror image on this model. Groups (the basal ganglia, the ventricles, the forebrain) are the one box all their members fit in together.
One adult, not everyone. The model is one adult male (BodyParts3D). Real brains differ from person to person, as the weight range above shows, so these are the sizes of one brain, not a standard and not a yardstick for anyone’s brain.

Pages not in the table, and why

47 parts too small for the atlas to draw (the substantia nigra, for one). The model has no shape for them, so their pages light and measure the larger part that holds them; that number is the holder’s size, not theirs, and listing it here would pass it off as theirs.
24 areas and named parts that the model draws only as part of a larger shape (Broca’s area, for one). Each of their pages measures the whole shape that holds it, which is not the area’s own size.
14 grooves (the central sulcus, for one). A groove is the gap between two shapes, not a shape; its page measures where its two banks meet.
8 cranial nerves the model has no shape for (the vagus nerve, for one). Their pages light and measure the part each leaves the brain from.
10 artery pages (the circle of Willis, for one). An artery’s box says how far its branches spread over the brain, not how big the vessel is; each artery page gives that spread, and the blood supply page shows them together.
The cerebral hemispheres: their page measures the left and right halves as two boxes; the cerebrum row here is both together.

Sources

Facts describe anatomy and normal function only. The 3D model is the adult male BodyParts3D brain (credits and licence); real brains vary in size and shape, so its measurements describe one model, not anyone’s brain.