Infrared light runs from roughly 700 nanometers upward, with near infrared at the short end and far infrared stretching thousands of nanometers longer.
A television remote fires invisible light at about 940 nm, while your body radiates most strongly near 10 µm — both infrared, separated by a factor of ten thousand in wavelength. That gap explains why the same word covers a remote control, a security camera, and a heating lamp. This guide lays out where each band sits, what the boundaries are, and what those differences mean for devices people buy.
Where Near And Far Infrared Sit On The Spectrum
Infrared begins just past visible red at roughly 700 nm; near infrared occupies the shorter half of the band, far infrared the long end. NASA places visible light at about 400–700 nm and defines infrared as everything longer. Beyond that, subdivisions depend on who is classifying.
Astronomy sources commonly split infrared into near (roughly 0.7–5 µm), mid (roughly 5–30 µm), and far (roughly 30–1,000 µm). NIST uses different operational ranges: near infrared around 750 nm–1.5 µm for imaging and security, and long-wave infrared around 7–15 µm for thermal imaging, without labeling that stretch “far infrared.” Both are correct within their fields.
The practical point: there is no single universal cutoff. Any article or product page claiming one fixed boundary is oversimplifying.
Near And Far Infrared Compared
| Band | Typical Range | Everyday Uses |
|---|---|---|
| Near infrared (NIR) | ~750 nm–1.5 µm (NIST); ~0.7–5 µm (astronomy) | Remote controls (~940 nm), security cameras, optical sensing, some light-therapy devices |
| Mid infrared | ~5–30 µm (NASA astronomy) | Scientific instruments, James Webb Space Telescope sensing |
| Long-wave infrared | ~7–15 µm (NIST LWIR) | Thermal imaging, firefighter cameras, long-range surveillance |
| Far infrared (FIR) | ~30–1,000 µm (NASA astronomy) | Heat sensing, thermal radiation studies |
| Thermal infrared | ~8–15 µm (Earth science) | Reading heat emitted by the planet and by warm objects |
What Actually Separates The Two Bands
Near infrared sits close enough to visible light that some cameras and sensors handle it with ordinary silicon hardware, while far infrared requires specialized detectors for longer waves. A phone camera can often pick up a remote’s ~940 nm flash though your eye cannot see it. Point that camera at a warm object and it shows nothing useful in the thermal range.
The reason is physics. A human body at normal temperature radiates most strongly near 10 µm, deep in LWIR thermal-camera territory. Silicon sensors do not respond there.
Heating lamps blur the line further. NASA notes infrared heating lamps commonly emit both visible and infrared energy across roughly 500–3,000 nm, spanning visible light through short-wave infrared. The glow you see is part of the output, not a separate phenomenon.
Neither band is automatically interchangeable for imaging, heating, or medical use. Detector materials, atmospheric transmission, emitted power, exposure time, and beam shape all shape what a device can do. If you are shopping for a lamp or therapy panel and want tested options rather than spec sheets, our tested infrared light picks compare real output and wavelength claims side by side.
Atmospheric transmission adds another wrinkle. NASA notes the atmosphere is largely opaque across much of the far infrared and submillimeter range, with only limited windows where those wavelengths pass. That is why JWST, which senses from 0.6–28 µm, orbits in space instead of peering from the ground.
What To Watch For Before Buying Or Trusting A Claim
Wavelength tells you where a device sits on the spectrum — not whether it is safe or effective. Common mix-ups:
- Treating “far infrared” as a synonym for all heat. Every infrared band can transfer energy and produce warming; wavelength alone does not establish effectiveness.
- Confusing wavelength with intensity. Irradiance, power density, distance, and exposure time determine delivered energy, not the nanometer figure alone.
- Assuming invisible means harmless. Infrared can heat skin and eyes; appearance is not a safety indicator.
- Reading one FDA-cleared device’s specs as proof a whole category works. Clearance applies only to the named model, its labeling, and its stated indications. One cleared infrared lamp uses 600–2,000 nm; its predicate used 5–25 µm. Those are device-specific facts, not rules about the wavelength family.
- Assuming a phone camera can detect any infrared. It may catch near infrared; longer thermal wavelengths need dedicated sensors.
Read the actual nanometer range and power rating on any product label. A vague “far infrared” claim without numbers tells you little. NIST’s infrared imaging guidance and NASA’s spectrum overview, linked below, are the strongest places to check what a given band can and cannot do.
Common Questions
Is near infrared the same as red light therapy?
Not exactly. Red light therapy usually refers to visible red wavelengths near 650 nm, while near infrared starts above roughly 750 nm and is invisible. Some devices combine both. Check the listed wavelength on a specific device rather than assuming a category label applies.
Can a smartphone camera see far infrared?
Generally no. Phone cameras can sometimes pick up near infrared such as a remote’s ~940 nm signal, but they lack detectors for thermal wavelengths in the 8–15 µm range. Thermal imaging requires dedicated hardware.
Why do sources disagree on where far infrared starts?
Because the boundaries come from different fields. NASA’s astronomy convention puts far infrared around 30–1,000 µm, while NIST emphasizes long-wave infrared around 7–15 µm for thermal work. Each set serves its own application, which is why articles should name the convention they use.
Sources
- NASA Science. “Infrared Waves” Supports wavelength ranges, remote control at ~940 nm, heating lamp output, and atmospheric opacity.
- NASA Science. “James Webb Space Telescope FAQs” Supports near, mid, and far infrared astronomy ranges and JWST’s 0.6–28 µm sensitivity.
- NIST. “Infrared Imaging” Supports NIR at 750 nm–1.5 µm and LWIR at 7–15 µm for security and thermal applications.