Half Dollar Coin Size at a Glance
The US half dollar coin measures 30.61 millimeters in diameter, is 2.15 millimeters thick, and weighs 11.340 grams for the modern cupronickel version. Its planchet features a reeded security rim and a core-to-clad ratio designed for vending and circulation durability. Below, we break down these specifications in an evergreen, verifiable format so you can reliably identify size, weight, and thickness in context.
Physical Dimensions of the Modern Half Dollar
Diameter and Thickness
The diameter of 30.61 mm places the half dollar between the quarter (24.26 mm) and the dollar coin (26.49 mm for the clad Kennedy), making it the largest current circulating coin by width. Its thickness of 2.15 mm is greater than that of a quarter (1.75 mm) and a dime (1.35 mm), but less than the dollar coin (2.0 mm clad and 2.15 mm for some SBA issues). These dimensions ensure the coin remains practical for hand transactions while remaining compatible with automated machines.
Weight and Planchet Composition
Each modern half dollar weighs 11.340 grams. The planchet is a clad sandwich with a copper core and outer layers of copper-nickel, which matches the weight and electromagnetic signature used by vending and parking equipment. For historical context, earlier 90% silver halves from 1964 and before weighed 12.5 grams and measured 30.61 mm as well, but had a different density and color. The current specifications balance legacy feel with modern production economics.
Verified Specifications Table
| Attribute | Verified Detail | Source Type |
|---|---|---|
| Diameter | 30.61 mm (1.205 in) | US Mint |
| Thickness | 2.15 mm (0.0846 in) | US Mint |
| Weight | 11.340 g (clad) | US Mint |
| Edge | Reeded with lettering “E PLURIBUS UNUM” | US Mint |
| Composition | Clad: Outer Cu–Ni 75/25, Core Cu pure | US Mint |
How the Half Dollar Compares
Compared with other US circulating coins, the half dollar is the broadest and heaviest currently in everyday use for commerce, even if it appears less frequently in daily transactions. Its size and weight make it easy to distinguish from quarters and dimes by hand feel, while remaining within the tolerances required for vending and parking machines.
- Quarter: 24.26 mm diameter, 1.75 mm thick, 5.670 g
- Dime: 17.91 mm diameter, 1.35 mm thick, 2.268 g
- Nickel: 21.21 mm diameter, 1.95 mm thick, 5.000 g
- Half Dollar: 30.61 mm diameter, 2.15 mm thick, 11.340 g
- Dollar Coin (clad): 26.49 mm diameter, 2.00 mm thick, 8.100 g
Design Elements Linked to Size
Obverse and Reverse Dimensions
The obverse features a portrait and inscriptions that scale with the 30.61 mm diameter, while the reverse design occupies the full planchet area. The lettering and heraldic elements are sized to remain legible at this width, and the reeded rim adds a tactile, security element that is standard across US clad coinage. The half dollar’s larger planchet also allows for finer detail in commemorative issues without reducing durability.
Security and Practicality
The reed edge, a direct carryover from earlier silver halves, serves both anti-counterfeiting and wear considerations. Because the coin is thicker than both the quarter and dime, it remains distinguishable in rolls and coin wrappers, and its weight helps it feed reliably in older vending mechanisms. These traits stem directly from its size and composition choices, which prioritize machine readability and circulation life.
Historical Size Consistency
Despite changes in composition, the modern half dollar has maintained a stable diameter since its introduction in the early 1970s at 30.61 mm. Earlier 90% silver halves shared the same diameter and thickness but weighed more due to silver’s density. The enduring dimensions highlight a deliberate standardization for automated equipment and public handling, making the half dollar a consistent reference point in US coin sizing.
Summary of Key Size Facts
Whether you are identifying coins in circulation, calibrating a vending machine, or comparing numismatic designs, the half dollar coin size is firmly established: 30.61 mm diameter, 2.15 mm thickness, and 11.340 grams for current cupronickel issues. Its reeded rim and clad planchet reflect decades of design choices aimed at durability, compatibility, and clear differentiation from other denominations. Understanding these specifications supports accurate handling, collection, and mechanical use of this long-running US coin.