The primary distinction between A15 and A19 light bulbs lies in their size and, consequently, their potential light output. The numerical designation refers to the bulb’s diameter in eighths of an inch. Therefore, an A15 bulb measures approximately 1 7/8 inches in diameter, while an A19 bulb is about 2 3/8 inches in diameter. This difference in size impacts the bulb’s surface area, which influences the amount of light it can emit.
The size variation is significant because it affects the internal components and, indirectly, the bulb’s application. A larger bulb, like the A19, typically has more space for a larger filament or more efficient LED components. Historically, the A19 has been the standard incandescent bulb size for general lighting purposes due to its balanced light output and compatibility with common lamp fixtures. The smaller A15 bulb is often chosen for appliances, chandeliers, or other fixtures where space is limited.
