The speed of a photon, and therefore all electromagnetic radiation, is approximately 299,792,458 meters per second (m/s) in a vacuum. This is often rounded to 300,000,000 m/s for simplicity.

This speed is also known as the speed of light, symbolized by c. It's a fundamental constant in physics and plays a crucial role in many theories, including Einstein's theory of relativity.

It's important to note that the speed of light can be slightly slower when it travels through a medium like water or glass.