Index finger
The index finger is the second finger of the human hand, located between the thumb and the middle finger.
How big is it?
8 cm long
Also 3.15 in
Length · example
A little perspective
Index finger vs Sand dollar: length comparison
The length of an index finger is approximately equal to the test diameter of a sand dollar.
The index finger is the second finger of the human hand, located between the thumb and the middle finger.
A sand dollar is a flat, burrowing sea urchin with a rigid, disc-shaped skeleton, often found in sandy coastal waters.
Both rulers start at the same zero and share one linear scale. Artwork keeps its original proportions.
Measurements, assumptions & sources +
Index finger
Length: 8 cm; example.
An 8 cm long example, not a population average.
Defined examples — our methodology
The marked length is calibrated. Unmeasured illustration details are representative.
Sand dollar
Defined test diameter: 8 cm; defined specimen; range 5 cm–10 cm.
A defined living sand dollar with an 8 cm test diameter and 25 g mass. Species and maturity vary; short spines are included visually but do not define the rigid test span.
Smithsonian Ocean — Sea urchins and sand dollars
The marked defined test diameter is calibrated. Unmeasured illustration details are representative.
Use the visual comparison to explore its scale, then check the measurements and sources.
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Why this measurement?
Why we use 8 cm
We compare the length of an index finger. This is an illustrative comparison value, not a claim that every example is the same.
An 8 cm long example, not a population average.
The marked horizontal span follows the measured feature, not the edges of the image. How calibrated comparisons work →
Recorded properties
Dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 8 cm | Not recorded | example |
Around this scale
Explore nearby values.
Compare examples with lower, similar and higher values. Each card names the measurement being compared.
Nearest lower valueEveryday objectsPeach7 cmDefined fruit diameterA peach is a juicy fruit with fuzzy skin and a central stone, grown on the tree Prunus persica.
Around the same scaleLiving thingsHummingbird8 cmLengthThe hummingbird is a tiny bird capable of hovering in mid-air by rapidly flapping its wings to feed on nectar.
Nearest higher valueSport and equipmentShuttlecock8.5 cmOverall lengthA shuttlecock is a feathered projectile used in badminton, designed to be struck by rackets.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
There’s always another scale
Follow your curiosity.
Living thingsSand dollar8 cmA sand dollar is a flat, burrowing sea urchin with a rigid, disc-shaped skeleton, often found in sandy coastal waters.SportShuttlecock8.5 cmA shuttlecock is a feathered projectile used in badminton, designed to be struck by rackets.Everyday thingsPeach7 cmA peach is a juicy fruit with fuzzy skin and a central stone, grown on the tree Prunus persica.
PeopleHuman heart12 cmA human heart is a muscular organ that pumps blood through the circulatory system.
Everyday thingsPomegranate10 cmA pomegranate is a round fruit from the Punica granatum tree, containing many edible seeds surrounded by juicy pulp.
Living thingsNudibranch10 cmA nudibranch is a soft-bodied marine mollusc, often brightly coloured, commonly known as a sea slug.
SportLacrosse ball6.35 cmA lacrosse ball is a solid rubber ball used in the sport of lacrosse, designed to meet official standards for play.
ContainersEspresso demitasse60 mlAn espresso demitasse is a small porcelain cup used for serving concentrated espresso coffee.