To calculate the frequency of a wavelength, you can use the formula: frequency = speed of light / wavelength. The speed of light is constant and is approximately 299,792,458 meters per second. So, for example, if you have a wavelength of 500 nanometers (nm), the frequency would be: 299,792,458 m/s / 500 x 10^-9 m = 599,584,916 Hz. This means the wave oscillates 599,584,916 times per second.