Half Dollar Size in Millimeters at a Glance
The US half dollar coin measures 30.61 millimeters in diameter and is approximately 2.15 millimeters thick, weighing 11.34 grams in its modern cupronickel composition. The coin has retained these core dimensional specifications since 1971, when its outer layer shifted from silver to a copper-nickel clad structure. Below is a concise breakdown of verified measurements and how they compare to everyday references.
Key Specifications of the Modern Half Dollar
Diameter, Thickness, and Weight
The diameter of 30.61 mm makes the half dollar notably larger than a quarter (24.26 mm) and nearly as wide as a US dollar coin (26.49 mm). Its thickness of 2.15 mm falls between the quarter and the smaller dime (1.35 mm). In terms of mass, the 11.34-gram half dollar is exactly twice the weight of a quarter and contributes to a substantial feel in the hand.
| Attribute | Verified Detail | Source Type |
|---|---|---|
| Diameter | 30.61 mm | US Mint Specification |
| Thickness | 2.15 mm | US Mint Specification |
| Weight | 11.34 g (cupronickel) | US Mint Specification |
| Edge | Lettered reeding: "E PLURIBUS UNUM" | US Mint Specification |
| Composition | Outer layer: copper 75%, nickel 25%; Core: pure copper | US Mint Specification |
Design and Obverse Elements
Obverse, Reverse, and Lettering
Since 1964, the obverse of the half dollar has featured a portrait of John F. Kennedy with the inscription "LIBERTY" above and the date below. The reverse displays a modified presidential seal with an eagle holding arrows and an olive branch, accompanied by "UNITED STATES OF AMERICA" and "HALF DOLLAR." Lettered edge details include "E PLURIBUS UNUM," a useful verification point for counterfeit detection.
Historical Size and Composition Context
From Silver to Clad Construction
Earlier half dollars—particularly those minted between 1965 and 1970—contain a silver core and outer layers, which slightly alter mass and electrical properties but not the overall diameter. Pre-1965 examples use 90% silver, while the present cupronickel-clad composition prioritizes durability and cost control. Across these changes, the 30.61 mm diameter has remained stable, ensuring continuity for vending machines, coin sorters, and public handling.
Practical Comparisons and Use Cases
Everyday and Collector Reference
For practical reference, the half dollar’s 30.61 mm diameter is comparable to a standard US button or a small poker chip, making it easy to visualize without precision tools. Collectors benefit from knowing that wear on the coin typically reduces measured diameter by mere fractions of a millimeter; significant variation may indicate tooling issues or nonstandard planchets.
- Quick sizing: half dollar is wider than a quarter, thicker than a dime, and close in diameter to some one-dollar tokens.
- Handling and vending: dimensions ensure reliable acceptance in mechanical devices designed for coins up to 31 mm.
- Condition matters: lightly circulated pieces retain near-original diameter, whereas heavily worn examples may measure slightly smaller.
Measurement Methods and Verification
How to Measure Diameter and Thickness
Use digital calipers for the most repeatable results: place the coin between the anvil and the jaw without applying excessive pressure, and record the widest point for diameter and the side-to-side thickness at multiple points to detect bending or rim distortion. Cross-check with a gauge card or certified reference coin when verifying authenticity or grading condition.
Common Questions on Half Dollar Dimensions
Size, Weight, and Fit in Everyday Contexts
Because the half dollar is larger and heavier than many modern coins, users often ask how it fits in coin wrappers, vending slots, and pocket change. Its enduring 30.61 mm size means it remains compatible with legacy equipment, while the 11.34 g weight gives it a premium feel. Understanding these metrics supports practical decisions for commerce, collections, and mechanical handling.