Human femur
The human femur is the thigh bone, connecting the hip to the knee and supporting body weight during movement.
Also known as: thigh bone, adult femur
How big is it?
45 cm tall
Also 17.72 in
Defined adult bone length · defined specimen
Typical recorded range: 40 cm to 50 cm.

A little perspective
About the same scale as Platypus.
Platypus: The platypus is a semi-aquatic mammal native to eastern Australia, notable for its duck-like bill and egg-laying reproduction.
Measurements, assumptions & sources +
Human femur
A defined adult human femur 45 cm long and about 300 g as a dry bone. Length, mass and morphology vary with the person; no clinical inference is intended.
Encyclopaedia Britannica — Femur
The marked defined adult bone length is calibrated. Unmeasured illustration details are representative.
Platypus
A representative adult platypus 50 cm from bill to tail and 1.5 kg. Sex and population affect size, and the broad tail is included in total length.
San Diego Zoo Wildlife Alliance — Platypus
The marked representative total length is calibrated. Unmeasured illustration details are representative.
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Why this measurement?
Why we use 45 cm
For comparison, this page uses defined adult bone length. This is labelled defined specimen: an explicit comparison model rather than a claim that every example has the same value. The recorded range is 40 cm to 50 cm.
A defined adult human femur 45 cm long and about 300 g as a dry bone. Length, mass and morphology vary with the person; no clinical inference is intended.
The marked vertical span follows the named feature; transparent margins and unmeasured details do not alter it. How calibrated comparisons work →
Recorded properties
Human femur dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 45 cm | 40 cm to 50 cm | defined specimen | |
| 300 g | 200 g to 400 g | defined specimen |
Around this scale
Go smaller. Go bigger.
These links use compatible length records, ordered around the selected value.
Nearest lower value · Everyday thingsA3 paper42 cmA3 paper is an ISO 216 paper format commonly used for drawings, diagrams and small posters.
Around the same scale · Living thingsCat46 cmA cat is a small domesticated mammal with a flexible body, retractable claws and highly developed senses.
Nearest higher value · PeopleNewborn baby50 cmA newborn baby is a human infant in the earliest period immediately after birth.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
- Encyclopaedia Britannica — FemurAdult femur anatomy; the atlas uses an explicitly defined 45 cm dry-bone specimen.
There’s always another scale






