A quarter is one of the most common coins used in everyday cash transactions, and understanding its exact size matters for both practical use and precise measurements. Many people ask how many mm is a quarter when budgeting, shipping small items, or comparing coin sizes across countries.
This overview breaks down the specifications, history, and practical uses of the quarter so you can quickly reference key facts without digging through multiple sources.
| Feature | United States Quarter | Canadian Quarter | Euro Coin (30c) |
|---|---|---|---|
| Diameter | 24.26 mm | 23.88 mm | 23.25 mm |
| Thickness | 1.75 mm | 1.7 mm | 2.14 mm |
| Mass | 5.67 g | 5.20 g | 16.25 g |
| Composition (core) | Cupronickel | Nickel-plated steel | Nordic gold alloy |
Physical Specifications of the US Quarter
The quarter’s dimensions are standardized across billions of coins, making it a reliable reference for quick comparisons and measurements. Precise tooling ensures that each coin fits vending machines, parking meters, and automated kiosks worldwide.
Diameter and Thickness Details
The quarter measures 24.26 mm in diameter and 1.75 mm in thickness, which translates to roughly 15/16 inch across and about 0.069 inch thick. These values are maintained by strict US Mint specifications to ensure consistency in cash handling equipment.
Historical Design and Composition Shifts
The quarter has evolved since 1796, reflecting changes in politics, technology, and material costs. Early iterations contained silver, while modern versions use a layered copper-nickel core to balance durability and cost.
Key Material Transitions
- 1796–1964: 90% silver alloy
- 1965–1998: Clad copper-nickel sandwich
- 1999–present: Copper core with bonded outer layers
Practical Uses in Everyday Life
Because the quarter’s size is standardized, it serves as a quick reference in workshops, retail, and shipping scenarios. Knowing how many mm is a quarter allows you to estimate gaps, tolerances, or packaging dimensions without specialized tools.
Common Real-World Applications
- Calibrating small-scale measurement tools
- Estimating object dimensions in a pinch
- Comparing international coin sizes
- Teaching basic metric and imperial conversions
Collectibility and Condition Grading
Collectors evaluate quarters based on wear, luster, and strike quality, with size consistency playing a role in grading. Even a slight deviation from 24.26 mm can indicate tooling issues or damage that affect value.
Factors Influencing Value
- Year and mint mark rarity
- Surface preservation and toning
- Certification by professional graders
- Error varieties like double dies
Key Takeaways for Practical Reference
- The quarter’s diameter is 24.26 mm and thickness is 1.75 mm
- Modern quarters use a copper-nickel clad composition
- Historical silver content affected both weight and intrinsic value
- Standardized size supports use in vending machines and measurement tasks
- Collector value depends more on condition and rarity than minor size variation
FAQ
Reader questions
How does the quarter’s size compare to a standard credit card?
A quarter has a diameter of 24.26 mm, while a credit card is about 85.60 mm long and 53.98 mm wide, making the card significantly larger than the coin.
Can the quarter’s dimensions change due to wear?
Light wear may flatten edges slightly, but official specifications of 24.26 mm diameter and 1.75 mm thickness remain the standard reference even for circulated coins.
Why is knowing how many mm is a quarter useful for shipping?
Knowing the quarter’s size helps you estimate internal packaging clearances and select appropriately sized boxes for small items or coin collections.
Are Canadian or Euro coins close in size to the US quarter?
Yes, the Canadian quarter at 23.88 mm and many Euro coins near 23–24 mm are close in diameter, though thickness and mass differ slightly.