What is the wavelength of visible light?

Visible light spans wavelengths from approximately 380 nm (violet) to 750 nm (red). In frequency terms, this corresponds to roughly 400 THz (red end) to 790 THz (violet end). Wavelengths shorter than 380 nm are ultraviolet; wavelengths longer than 750 nm are infrared.

How do I convert frequency to wavelength?

Use the equation λ = c ÷ f, where c = 299,792,458 m/s (speed of light), f is frequency in Hz, and λ is wavelength in meters. For example, green light at 550 THz (5.5 × 10¹⁴ Hz): λ = 299,792,458 ÷ 5.5 × 10¹⁴ ≈ 545 nm.

What color has the highest frequency?

Violet light has the highest frequency in the visible spectrum, at approximately 668–789 THz, corresponding to wavelengths of 380–450 nm. Higher frequency means higher photon energy (E = hf). Beyond violet, ultraviolet (UV), X-rays, and gamma rays have even higher frequencies — but they are invisible to the human eye.

Wavelength and Frequency Guide: c = fλ, Visible Light Spectrum & EM Waves

The Fundamental Relationship: c = f × λ

Every electromagnetic wave obeys the equation:

c = f × λ

where:

c = speed of light in a vacuum = 299,792,458 m/s (exact)
f = frequency in hertz (Hz)
λ (lambda) = wavelength in meters

Rearranging: λ = c ÷ f and f = c ÷ λ. Because c is constant, frequency and wavelength are inversely proportional — higher frequency always means shorter wavelength, and vice versa.

The Electromagnetic Spectrum

The EM spectrum spans over 20 orders of magnitude in frequency. All EM waves travel at c in vacuum and differ only in frequency (and thus wavelength and energy). The table below gives representative ranges for each band.

Band	Frequency Range	Wavelength Range	Common Uses
Radio waves	3 Hz – 300 GHz	1 mm – 100,000 km	Broadcasting, Wi-Fi, radar
Microwaves	300 MHz – 300 GHz	1 mm – 1 m	Microwave ovens, 5G, satellite
Infrared (IR)	300 GHz – 430 THz	700 nm – 1 mm	Heat sensing, remote controls
Visible light	430 – 790 THz	380 – 700 nm	Human vision
Ultraviolet (UV)	790 THz – 30 PHz	10 – 380 nm	Sterilization, sunburn
X-rays	30 PHz – 30 EHz	0.01 – 10 nm	Medical imaging, security
Gamma rays	>30 EHz	<0.01 nm	Nuclear physics, cancer therapy

Visible Light Spectrum by Color

Human vision responds to wavelengths between roughly 380 nm and 750 nm. Within this narrow band, wavelength determines perceived color. The table uses consensus values from the CIE and optics literature.

Color	Wavelength Range (nm)	Frequency Range (THz)	Photon Energy (eV)
Violet	380 – 450	666 – 789	2.76 – 3.26
Blue	450 – 495	606 – 666	2.51 – 2.76
Cyan	495 – 520	577 – 606	2.39 – 2.51
Green	520 – 565	531 – 577	2.19 – 2.39
Yellow	565 – 590	508 – 531	2.10 – 2.19
Orange	590 – 625	480 – 508	1.98 – 2.10
Red	625 – 750	400 – 480	1.65 – 1.98

Wavelength and Photon Energy

Photon energy is related to frequency by E = h × f, where h = 6.626 × 10−³&sup4; J·s (Planck's constant). Since f = c / λ, energy also equals E = h × c / λ. This means shorter wavelength (higher frequency) photons carry more energy — which is why UV radiation can damage DNA while visible light does not.

Worked Example

What is the wavelength of a 100 MHz FM radio signal?

f = 100 MHz = 1 × 10&sup8; Hz
λ = c ÷ f = 299,792,458 ÷ 100,000,000 ≈ 3.00 m

FM radio antennas are typically half a wavelength long (≈ 1.5 m) for optimal reception — a direct application of this formula.

Explore speed unit conversions with our speed converter, or convert energy units related to photon energy with our energy converter.