Convert hertz [Hz] to femtohertz [fHz] Online | Free frequency-wavelength Converter

The Fundamental Unit of Frequency

The hertz (Hz) is the standard unit of frequency in the International System of Units (SI), defined as one cycle per second. It measures how often a repeating event occurs each second, making it a fundamental concept in physics, engineering, and many branches of science.

Frequency measured in hertz is essential for understanding waves and oscillations, including sound waves, electromagnetic waves, and mechanical vibrations. For example, in acoustics, the pitch of a sound corresponds directly to its frequency in hertz—middle C on a piano has a frequency of about 261.6 Hz.

In electrical engineering, hertz measures the frequency of alternating current (AC), with common household power typically operating at 50 or 60 Hz depending on the country. Radio and television broadcasting frequencies, as well as wireless communication signals, are also expressed in hertz and its multiples.

Because hertz represents a single cycle per second, it serves as the base unit from which all other frequency units are derived, including kilohertz, megahertz, and gigahertz. Understanding frequency in hertz allows scientists and engineers to design and analyze systems ranging from audio equipment to complex telecommunications networks.

Exploring Extremely Low Frequency Phenomena

The femtohertz (fHz) is a unit of frequency equal to 10⁻¹⁵ hertz, representing one cycle per 1,000,000,000,000,000 seconds—which is about 31.7 million years. This incredibly low frequency scale is used primarily in astrophysics, cosmology, and geophysics to describe ultra-slow oscillations and waves occurring over vast cosmic timescales.

Frequencies in the femtohertz range are associated with phenomena such as primordial gravitational waves, oscillations in the cosmic microwave background radiation, and long-term magnetic or seismic cycles on Earth. These waves have correspondingly immense wavelengths, stretching over billions of kilometres or even larger cosmic distances.

Because femtohertz frequencies are far beyond everyday human experience, they are mostly relevant for understanding the deep-time evolution of the universe and large-scale cosmic processes. Studying such slow oscillations helps scientists learn about the formation of galaxies, the behavior of space-time, and fundamental physical laws governing the cosmos.

Using femtohertz as a measurement allows researchers to quantify these vast time periods and wavelengths, connecting tiny frequency values with the immense scale of astrophysical phenomena and Earth’s geological history.