£1 coin
A £1 coin is a twelve-sided British coin used as standard currency in the United Kingdom.
How big is it?
2.343 cm · specified maximum diameter
Also 0.922 in
Specified maximum diameter · specified
Format: Twelve-sided, bimetallic. £1 coin: 23.43 mm (0.922 in) maximum span, 2.8 mm (0.110 in) thick, and 8.75 g in mass. Diameter measures across the face, not the edge thickness.
Check £1 coin material and older-format differences. Compare UK and US coin dimensions.
A little perspective
£1 coin vs Human eyeball: diameter comparison
The globe diameter of the human eyeball is about 1.02 times the maximum diameter of a £1 coin.
A £1 coin is a twelve-sided British coin used as standard currency in the United Kingdom.
The human eyeball is the globe-shaped organ that receives light and begins the process of vision.
Both rulers start at the same zero and share one linear scale. Artwork keeps its original proportions.
Measurements, assumptions & sources +
£1 coin
Specified maximum diameter: 2.343 cm; specified.
Twelve-sided bimetallic UK pound introduced on 28 March 2017: 23.43 mm maximum point-to-point span, 2.80 mm published thickness and 8.75 g mass. The older round pound was 22.5 mm across, 3.15 mm thick and 9.50 g; its legal tender status ended on 15 October 2017. Specimen rim measurements are not official thickness tolerances.
Royal Mint — £1 coin specifications
The marked specified maximum diameter is calibrated. Unmeasured illustration details are representative.
Human eyeball
Representative globe diameter: 2.4 cm; representative; range 2.3 cm–2.5 cm.
A representative adult human eye globe about 24 mm across. The corneal bulge and optic nerve are contextual and excluded from the calibrated globe diameter.
Encyclopaedia Britannica — Human eye
The marked representative globe 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 2.343 cm
We compare the maximum diameter of a £1 coin. This value follows a stated specification; check its scope in the notes.
Twelve-sided bimetallic UK pound introduced on 28 March 2017: 23.43 mm maximum point-to-point span, 2.80 mm published thickness and 8.75 g mass. The older round pound was 22.5 mm across, 3.15 mm thick and 9.50 g; its legal tender status ended on 15 October 2017. Specimen rim measurements are not official thickness tolerances.
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 |
|---|---|---|---|
| 23.43 mm (0.922 in) | Not recorded | specified - Twelve-sided, bimetallic | |
| 8.75 g | Not recorded | specified - Twelve-sided, bimetallic | |
| 2.8 mm (0.110 in) | Not recorded | specified - Twelve-sided, bimetallic |
Around this scale
Explore nearby values.
Compare examples with lower, similar and higher values. Each card names the measurement being compared.
Nearest lower valueEveryday objectsUK 20p coin2.14 cmSpecified maximum diameterA UK 20p coin is the seven-sided twenty-pence denomination of the decimal pound sterling circulation coinage.
Around the same scaleEveryday objectsUS quarter2.426 cmDiameterA US quarter is a coin worth twenty-five cents, commonly used in United States currency.
Nearest higher valueEveryday objectsCacao bean2.4 cmDefined dry-bean lengthA cacao bean is the dried seed of the Theobroma cacao tree, used to produce cocoa and chocolate.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
- Royal Mint — £1 coin specificationsTwelve-sided format: 23.43 mm maximum span, 2.80 mm thickness, 8.75 g. Older round format: 22.5 mm diameter, 3.15 mm thickness, 9.50 g. Introduction and withdrawal dates are distinct.
More ways to see it
Curated comparisons
There’s always another scale
Follow your curiosity.
PeopleHuman eyeball2.4 cmThe human eyeball is the globe-shaped organ that receives light and begins the process of vision.Everyday thingsUS quarter2.426 cmA US quarter is a coin worth twenty-five cents, commonly used in United States currency.
Living thingsSea angel2 cmA sea angel is a small, transparent swimming sea slug with wing-like appendages, found in cold ocean waters.
Everyday thingsUK 10p coin2.45 cmA UK 10p coin is the ten-pence denomination of the decimal pound sterling circulation coinage.
SportSquash ball4 cmA squash ball is a small, hollow rubber ball used in the sport of squash.Everyday thingsUK 20p coin2.14 cmA UK 20p coin is the seven-sided twenty-pence denomination of the decimal pound sterling circulation coinage.
Living thingsBird’s nest fungus2 cmBird’s nest fungus is a small fungus whose fruiting body resembles a tiny nest containing spore-filled capsules called peridioles.
PeopleFingernail1.5 cmA fingernail is the hard, protective covering at the tip of a human finger, composed of keratin.A closer look