Spectral ranges: from UV-C to IR-C
The boundaries between UV-C, UV-B, UV-A, visible radiation and infrared are not given by physics. They are defined – and they differ from one standard to the next. Anyone assigning an irradiance to a spectral band needs to know which convention they are using: between the international and the common US definition there are five nanometres at the UV-B boundary, and they decide whether a reading falls into one band or the other.
This page lists the classification to DIN/ISO 20473 and sets out where CIE, WHO and US practice depart from it.
Spectral ranges to DIN/ISO 20473
| Designation | Symbol | Wavelength range |
|---|---|---|
| Ultraviolet C | UV-C | 100–280 nm |
| of which vacuum UV | VUV | 100–200 nm |
| of which Far-UVC | – | 200–230 nm (not a category of the standard, common designation in practice) |
| Ultraviolet B | UV-B | 280–315 nm |
| Ultraviolet A | UV-A | 315–380 nm |
| Visible radiation | VIS | 380–780 nm |
| Infrared A | IR-A | 780–1400 nm |
| Infrared B | IR-B | 1400–3000 nm |
| Infrared C | IR-C | 3000 nm to 1 mm |
| of which mid infrared | MIR | 3000–50,000 nm |
| of which far infrared | FIR | 50,000 nm to 1 mm |
Additional standards and classifications of spectral ranges
In some areas of photobiology, the wavelength ranges are subdivided from 200 nm to 290 nm, from 290 nm to 320 nm and from 320 nm to 400 nm. Sometimes these wavelength ranges are (incorrectly) referred to as UV-A, UV-B and UV-C. Ultraviolet radiation with wavelengths of less than 180 nm is referred to as vacuum UV radiation. It should be noted that radiation between 380 nm and 400 nm is referred to as visible radiation, although this wavelength range is by definition also in the UV radiation range.
In standards for protection against solar radiation, for example in sunglasses for general use, the upper limit of UV-A is sometimes assumed to be 380 nm. In standards with protection requirements against radiation from artificial sources, the upper limit of UV-A is usually assumed to be 400 nm, which is consistent with the CIE definition. The upper limit of 400 nm is used by ICNIRP, ACGIH, the World Health Organization and in the Directive of the European Parliament and of the Council on the protection of health and safety from the dangers of artificial optical radiation, among others.
In some applications, the ultraviolet spectrum has also been subdivided into "far ultraviolet", "vacuum ultraviolet" and "near ultraviolet"; however, the boundaries necessarily vary depending on the application (e.g. in meteorology, optical design, photochemistry and thermal physics).
In conclusion, it can be said that the classification of spectral ranges into UV radiation, light and IR radiation is application-related.
Normative classification of UV radiation
The classification of ultraviolet (UV) radiation into spectral ranges varies depending on the standard and application. The different spectral ranges of UV radiation and their classification in various standards as well as their specific applications are described in detail below.
The International Organization for Standardization (ISO), the German Institute for Standardization and other organizations, such as the CIE, have defined spectral ranges for the applications. These are not always the same. However, the most common classification is:
The classification of the spectral ranges for UV radiation to IR radiation according to e-ILV of the CIE & standard CIE S 017/E:2020 ILV:
The following standards have their own classification of spectral ranges for UV radiation
DIN EN ISO 24444:2022-07 Cosmetic products, especially for test methods for sunscreens and the in vivo determination of the sun protection factor
DIN EN ISO 24443:2022-08 Cosmetic products, application in the field of test methods for sunscreen products
DIN EN ISO 24442:2022-10 Determination of the UVA sun protection factor
DIN EN ISO 18369-1:2018-04 Ophthalmic optics - Contact lenses - Part 1: Definitions, classification of contact lens materials and recommendations for the notation of contact lens specifications
DIN EN 16981:2021-12 Photocatalysis - Glossary of terms;
DIN EN IEC 62471-7; VDE 0837-471-7:2024-04 Photobiological safety of lamps and lamp systems
ISO 20473:2007-04 Optics and photonics - Spectral bands
DIN EN 16782:2016-07 Preservation of cultural heritage - Cleaning of porous inorganic materials - Laser cleaning processes for cultural heritage
DIN EN ISO 4007:2020-01 Personal protective equipment - Eye and face protection
DIN EN ISO 29464:2020-09 Cleaning of air and other gases
DIN EN ISO 9488:2022-12 Solar energy
DIN EN 13758-1:2007-03 Textiles - Protective properties against ultraviolet solar radiation - Part 1: Test method for garment textiles
DIN EN ISO 105-A08:2003-01 Textiles - Tests for color fastness - Part A08: Vocabulary of colorimetry
DIN EN ISO 14692-1:2018-02 Petroleum and natural gas industries - Glass-reinforced plastic (GRP) piping - Part 1: Terms, symbols, applications and materials
DIN EN 1330-1:2015-05 Non-destructive testing - Terminology
You can download a list of spectral ranges for the standards above here
Where the conventions diverge
| Band | DIN/ISO 20473 | CIE S 017 (ILV) | WHO and ICNIRP | USA (EPA, photobiology) |
|---|---|---|---|---|
| UV-C | 100–280 nm (in practice 200–280 nm) | 100–280 nm | 100–280 nm | 100–290 nm |
| UV-B | 280–315 nm | 280–315 nm | 280–315 nm | 290–320 nm |
| UV-A | 315–380 nm | 315–400 nm | 315–400 nm | 320–400 nm |
| Visible | 380–780 nm | lower limit 360–400 nm, upper 760–830 nm | not defined | 400–700 nm |
Explore the spectral ranges interactively
The explorer follows the classification of CIE S 017 (ILV) and shows the spectral range, the associated quantities and the typical source for every wavelength. Where the conventions diverge — for instance in the section between 380 and 400 nm, which the standard assigns to both UVA and the visible range — it says so explicitly.
Why the boundaries differ
315 against 320 nanometres. The internationally standardised boundary between UV-B and UV-A is 315 nm. US photobiology and EPA publications mostly divide at 320 nm. The difference comes from the erythema action spectrum: the action curve falls by several orders of magnitude between 300 and 330 nm, and where the line is drawn is a convention, not a measurement. In practice this means: a figure in mW/cm² UV-B is not comparable without the classification it refers to.
380 against 400 nanometres. DIN/ISO 20473 ends UV-A at 380 nm – under that standard visible radiation begins there, and the optical spectrum is divided without gaps. Health and safety practice uses 400 nm instead: ICNIRP, ACGIH, the World Health Organization and EU Directive 2006/25/EC on artificial optical radiation put the upper UV-A limit there. Standards for protection against solar radiation – sunglasses, for instance – sometimes go back to 380 nm.
In practice: anyone working with UV LEDs at 395 or 405 nm is operating exactly on that boundary. Under ISO 20473 that is visible radiation, under ICNIRP it is UV-A with an exposure limit – and both readings appear side by side in the same test reports.
100 against 200 nanometres. Both figures are correct; they simply serve different purposes. The international classification to DIN/ISO 20473 and CIE S 017 puts UV-C at 100 to 280 nm. The practical classification starts at 200 nm, because oxygen absorbs the radiation below that: under roughly 200 nm, UV no longer propagates in air but splits oxygen and forms ozone. Anyone designing an irradiation system or selecting a sensor therefore works with 200 to 280 nm; anyone quoting a standard, with 100 to 280 nm.
What this means for measurement
A UV sensor does not measure “UV-A”. It measures a weighted sum over its own spectral responsivity, and that curve has soft flanks which never coincide exactly with a standard boundary. Two sensors both labelled “UV-A” can return different readings on the same lamp – not because one is wrong, but because they weight differently.
Three consequences for everyday work:
- Every reading needs the spectral range of the sensor alongside it, not just the abbreviation. The ranges of the Opsytec sensors are listed on the UV sensor pages.
- With narrowband sources – UV LEDs – the position of the peak wavelength relative to the sensor flank decides the reading. A spectroradiometer is the safe choice here.
- Readings only become comparable through traceable calibration to ISO 17025.
The underlying terms – what UV radiation is, why “UV light” strictly speaking does not exist and which standards use their own classifications – are covered under What is UV radiation, which also offers the list of standards with differing spectral ranges for download.
For download: Spectral ranges and standards as a PDF – the list of standards that define their own spectral ranges, with the respective limits. On to the quantities and units: radiometric quantities for radiant power, irradiance and dose, photometric quantities for luminous flux, illuminance and luminance.
The standards deal with spectral radiation measurement; emitters for spectral radiation measurements and radiation physics in the optical field and lighting technology
The classification of spectral ranges according to ISO 21348:2007
The following table provides a detailed overview of the spectral ranges for UVA, UVB and UVC in nanometers (nm) and takes into account specific fields of application in the aerospace industry. It serves to determine solar radiation in natural and artificial environments and is used for designs in the aerospace industry.
| name | Spectral range |
| Vacuum-UV, VUV | 10 nm to 200 nm |
| Extreme UV, EUV | 10 nm to 121 nm |
| FUV, FAR Ultraviolet | 122 nm to 200 nm |
| Ultraviolet C, UVC | 100 nm to 280 nm |
| Ultraviolet B, UVB | 280 nm to 315 nm |
| Near Ultraviolet , NUV | 300 nm to 400 nm |
| UV-A | 315 nm to 400 nm |
| Visible, VIS | 380 nm to 760 nm |
| Purple | 360 nm to 450 nm |
| Blue | 450 nm to 500 nm |
| Green | 500 nm to 570 nm |
| Yellow | 570 nm to 591 nm |
| Orange | 591 nm to 610 nm |
| Red | 610 nm to 760 nm |
| Infrared, IR | 760 nm to 1000000 nm |
| Near Infrared, IR-A | 760 nm to 1400 nm |
| Middle Infrared, IR-B | 1400 nm to 3000 nm |
| Far Infrared, IR-C | 3000 nm to 1000000 nm |
Alongside 100 nm, the tables above also give 200 nm as a boundary for UV-C. That is the practical boundary: below roughly 200 nm oxygen absorbs the radiation, it no longer propagates in air and forms ozone instead. The international classification to CIE S 017 and DIN/ISO 20473 starts at 100 nm and includes the vacuum UV.
* There are no precise limits to the spectral range of visible radiation as they depend on the amount of radiation flux reaching the retina and the sensitivity of the observer. The lower limit is generally set between 360 nm and 400 nm and the upper limit between 760 nm and 830 nm.
The e-ILV provides free access to all terms and definitions contained in the international standard CIE S 017/E:2020 ILV: International Lighting Vocabulary, 2nd edition.
In the past, the following classification of UV radiation was used more frequently, especially in the trilingual area:
The spectral ranges for UV to IR radiation according to DIN 5030-2:1982-09 (current) & DIN 5031-7:1984 (withdrawn)
An Overview of the Spectral Ranges of Various Standards
There are no precise limits for the spectral range of visible radiation since they depend upon the amount of radiant flux reaching the retina and the responsivity of the observer. The lower limit is generally taken between 360 nm and 400 nm and the upper limit between 760 nm and 830 nm.
Source: https://cie.co.at/eilvterm/17-21-009
| Designation | Spectral range |
|---|---|
| UV-A | 315 nm to 400 nm |
| UV-B | 280 nm to 315 nm |
| UV-C | 200 nm to 280 nm |
| visible radiation | – |
| IR-A | 780 nm to 1400 nm |
| IR-B | 1400 nm to 3000 nm |
| IR-C | 3000 nm to 1000000 nm |
Cosmetic products, especially for test methods for sunscreen products and the in vivo determination of the sun protection factor
| Designation | Spectral range |
|---|---|
| UV-A | 320 nm to 400 nm |
| UVA II | 320 nm to 340 nm |
| UVA I | 340 nm to 400 nm. |
| UV-B | 290 nm to 320 nm |
Cosmetic products, application in the field of test methods for sunscreen products
| Designation | Spectral range |
|---|---|
| UV, ultraviolet radiation | 290 nm to 400 nm |
| UV-A | 320 nm to 400 nm |
| UVA II | 320 nm to 340 nm |
| UVA I | 340 nm to 400 nm. |
| UV-B | 290 nm to 320 nm |
Determination of UVA sun protection
| Designation | Spectral range |
|---|---|
| UV-A | 320 nm to 400 nm |
| UVA II | 320 nm to 340 nm |
| UVA I | 340 nm to 400 nm. |
| UV-B | 290 nm to 320 nm |
Ophthalmic optics - Contact lenses - Part 1: Terms, classification of contact lens materials and recommendations for writing contact lens specifications
| Designation | Spectral range |
|---|---|
| UV-A | 315 nm to 380 nm |
| UV-B | 280 nm to 315 nm |
Aerospace - Electrical cables for aerospace applications
| Designation | Spectral range |
|---|---|
| UV, ultraviolet | 200 nm to 400 nm |
Aerospace - Wire and cable marking processes using UV lasers
| Designation | Spectral range |
|---|---|
| UV, ultraviolet | 200 nm to 400 nm |
The designation and the limits of the various ranges correspond to the recommendation of the International Commission on Illumination (CIE), with the exception that in these recommendations the UV-C range is 100 nm to 280 nm and thus includes the vacuum UV range.
| Designation | Spectral range |
|---|---|
| UV, Ultraviolet | 100 nm to 400 nm |
| Vacuum ultraviolet (VUV) | 100 nm to 200 nm |
| UV-C | 200 nm to 280 nm |
| UV-B | 280 nm to 315 nm |
| UV-A | 315 nm to 400 nm |
Photobiological safety of lamps and lamp systems. Measuring methods
| Designation | Spectral range |
|---|---|
| UVA, Near UV | 315 nm to 400 nm |
Photobiological safety of lamps and lamp systems. Guideline for manufacturer requirements regarding the radiation safety of optical sources that are not lasers
| Designation | Spectral range |
|---|---|
| UVA, Near UV | 315 nm to 400 nm |
Photobiological safety of lamps and lamp systems - Part 6: Products emitting ultraviolet radiation (IEC 62471-6:2022)
| Designation | Spectral range |
|---|---|
| ultraviolet radiation | 100 nm to 400 nm |
| UV-C | 100 nm to 280 nm |
| UV-B | 280 nm to 315 nm |
| UV-A | 315 nm to 400 nm |
Photobiological safety of lamps and lamp systems
In some applications, the ultraviolet spectrum has also been subdivided into "far ultraviolet", "vacuum ultraviolet" and "near ultraviolet"; however, the boundaries necessarily vary depending on the application (e.g. in meteorology, optical design, photochemistry and thermal physics).
| Designation | Spectral range |
|---|---|
| ultraviolet radiation, UV radiation, UVR | 100 nm to 400 nm |
| UV-C | 100 nm to 280 nm |
| UV-B | 280 nm to 315 nm |
| UV-A | 315 nm to 400 nm |
Photobiological safety of lamps and lamp systems
The range of ultraviolet radiation between 100 nm and 400 nm is usually divided into: UV-A from 315 nm to 400 nm; UV-B from 280 nm to 315 nm; UV-C from 100 nm to 280 nm. These designations for UV radiation should not be understood as exact limits, especially for photobiological effects. In some areas of photobiology, the wavelength ranges are subdivided from 200 nm to 290 nm, from 290 nm to 320 nm and from 320 nm to 400 nm. Sometimes these wavelength ranges are (incorrectly) referred to as UV-A, UV-B and UV-C. Ultraviolet radiation with wavelengths of less than 180 nm is referred to as vacuum UV radiation. It should be noted that radiation between 380 nm and 400 nm is referred to as visible radiation, although this wavelength range is by definition also in the UV radiation range.
| Designation | Spectral range |
|---|---|
| ultraviolet radiation | 100 nm to 400 nm |
| UV-C | 100 nm to 280 nm |
| UV-B | 280 nm to 315 nm |
| UV-A | 315 nm to 400 nm |
Spectral radiation measurement; emitters for spectral radiation measurements; selection criteria
Radiation physics in the optical field and lighting technology - Supplement 1: Table of contents on quantities, formula symbols and units and index to DIN 5031
| Designation | Spectral range |
|---|---|
| UV-C | 100 nm to 280 nm |
| VUV | 100 nm to 200 nm |
| FUV | 200 nm to 280 nm |
| UV-B | 280 nm to 315 nm |
| UV-A | 315 nm to 400 nm |
| VIS | 380 nm to 780 nm |
| IR-A | 780 nm to 1400 nm |
| IR-B | 1400 nm to 3000 nm |
| IR-C | 3000 nm to 1000000 nm |
| MIR | 3000 nm to 50000 nm |
| FIR | 50000 nm to 1000000 nm |
Space flight environment (natural and artificial) - Determination of solar radiation
| Designation | Spectral range |
|---|---|
| Vacuum-UV, VUV | 10 nm to 200 nm |
| Extreme UV, EUV | 10 nm to 121 nm |
| FUV, FAR Ultraviolet | 122 nm to 200 nm |
| Ultraviolet C, UVC | 100 nm to 280 nm |
| Ultraviolet B, UVB | 280 nm to 315 nm |
| Near Ultraviolet, NUV | 300 nm to 400 nm |
| UV-A | 315 nm to 400 nm |
| Visible, VIS | 380 nm to 760 nm |
| Purple | 360 nm to 450 nm |
| Blue | 450 nm to 500 nm |
| Green | 500 nm to 570 nm |
| Yellow | 570 nm to 591 nm |
| Orange | 591 nm to 610 nm |
| Red | 610 nm to 760 nm |
| Infrared, IR | 760 nm to 1000000 nm |
| Near Infrared, IR-A | 760 nm to 1400 nm |
| Middle Infrared, IR-B | 1400 nm to 3000 nm |
| Far Infrared, IR-C | 3000 nm to 1000000 nm |
Extreme UV, EUV: This definition is commonly used by data providers of this spectral category as well as by the materials sciences community
FUV, FAR Ultraviolet: This definition is commonly used by the aeronomy community
UV-C equipment - Safety information - Permissible exposure of persons
| Designation | Spectral range |
|---|---|
| Vacuum UV | 100 nm to 200 nm |
| UV-C | 100 nm to 280 nm |
| UV-B | 280 nm to 315 nm |
| UV-A | 315 nm to 400 nm |
| Designation | Spectral range |
|---|---|
| ultraviolet | optical radiation whose wavelength is shorter than that of visible radiation |
Aerospace series - Electrical cables for aerospace use - Test methods
| Designation | Spectral range |
|---|---|
| ultraviolet | 200 nm to 400 nm |
Aerospace - Wire and cable marking processes using UV lasers
| Designation | Spectral range |
|---|---|
| ultraviolet | 200 nm to 400 nm |
Photocatalysis - Glossary of terms;
| Designation | Spectral range |
|---|---|
| Vacuum ultraviolet (VUV) | 100 nm to 200 nm |
| UV-C | 200 nm to 280 nm |
| UV-B | 280 nm to 315 nm |
| UV-A | 315 nm to 400 nm |
UV-C: Note 1 to entry: This area is divided into four sub-bands as follows: - Vacuum ultraviolet (VUV) 100 nm to 200 nm; - UV-C 200 nm to 280 nm; - UV-B 280 nm to 315 nm; - UV-A 315 nm to 400 nm.
UV-B: The designation and boundaries of the various areas correspond to the Recommendation of the International Commission on Illumination (CIE), with the exception that in these recommendations the UV-C range is 100 nm to 280 nm and thus includes the vacuum UV range.
Ophthalmic optics - Spectacle lenses
| Designation | Spectral range |
|---|---|
| ultraviolet radiation | optical radiation whose wavelengths are shorter than those of visible radiation |
ISO 20473 specifies the spectral range of ultraviolet radiation for use in optics and photonics standards and divides it into: - UV-A: 315 nm to 380 nm; - UV-B: 280 nm to 315 nm; - UV-C: 100 nm to 280 nm. In other health and safety areas, UV-A is defined as 315 nm to 400 nm
| Designation | Spectral range |
|---|---|
| UV-C | 200 nm to 280 nm |
| UV-B | 280 nm to 315 nm |
| UV-A | 315 nm to 380 nm |
Railroad applications - Front windows for rail vehicles
| Designation | Spectral range |
|---|---|
| ultraviolet radiation, UV | 200 nm and 380 nm |
Preservation of cultural heritage - Artificial ageing of untreated or treated porous inorganic material surfaces with simulated solar radiation
| Designation | Spectral range |
|---|---|
| ultraviolet radiation, UV | 100 nm to 400 nm |
| UV-C | 200 nm to 280 nm |
| UV-B | 280 nm to 315 nm |
| UV-A | 315 nm to 400 nm |
Preservation of cultural heritage - cleaning of porous inorganic materials - Laser cleaning process for cultural heritage
| Designation | Spectral range |
|---|---|
| ultraviolet radiation | 10 nm to 380 nm |
Personal protective equipment - eye and face protection
In standards for protection against solar radiation, for example in sunglasses for general use, the upper limit of UV-A is sometimes assumed to be 380 nm. In standards with protection requirements against radiation from artificial sources, the upper limit of UV-A is usually assumed to be 400 nm, which is consistent with the CIE definition. The upper limit of 400 nm is used by ICNIRP, ACGIH, the World Health Organization and in the Directive of the European Parliament and of the Council on the protection of health and safety from the dangers of artificial optical radiation, among others.
| Designation | Spectral range |
|---|---|
| ultraviolet radiation, UV radiation, UVR | optical radiation whose wavelengths are shorter than those of visible radiation |
Purification of air and other gases
| Designation | Spectral range |
|---|---|
| ultraviolet radiation, UV | 100 nm to 400 nm |
| UV-C | 200 nm to 280 nm |
| UV-B | 280 nm to 315 nm |
| UV-A | 315 nm to 400 nm |
Solar energy
| Designation | Spectral range |
|---|---|
| ultraviolet radiation | 10 nm to 400 nm |
| UV-C | 200 nm to 280 nm |
| UV-B | 280 nm to 315 nm |
| UV-A | 315 nm to 400 nm |
Aerospace construction
| Designation | Spectral range |
|---|---|
| ultraviolet radiation, UV radiation | none |
Textiles - Protective properties against ultraviolet solar radiation - Part 1: Test methods for apparel textiles;
| Designation | Spectral range |
|---|---|
| ultraviolet radiation, UVR | 180 nm to 400 nm |
| – | 200 nm to 280 nm |
| – | 280 nm to 315 nm |
| – | 315 nm to 400 nm |
Textiles - Tests for color fastness - Part A08: Vocabulary of colorimetry
The limit values of the spectral range of ultraviolet radiation are not precisely defined and may vary depending on the application.
| Designation | Spectral range |
|---|---|
| ultraviolet radiation, UV radiation | Radiant energy with wavelengths of the monochromatic components shorter than those of visible radiation and greater than about 100 nm |
Petroleum and natural gas industries - Glass fiber reinforced plastic (GRP) piping - Part 1: Terms, symbols, applications and materials
| Designation | Spectral range |
|---|---|
| ultraviolet radiation, UV radiation | electromagnetic radiation in the frequency band immediately above the visible spectrum |
Non-destructive testing - Terminology
| Designation | Spectral range |
|---|---|
| ultraviolet radiation | none |
Author: Dr. Mark Paravia
Dr.-Ing. Mark Paravia is the managing director of Opsytec Dr. Gröbel GmbH in Ettlingen and heads the accredited calibration laboratory. Following his research on pulsed xenon excimer discharges at the Institute of Lighting Technology at KIT, his current focus is on optical radiation measurement technology. He is vice-chair of the DIN Standards Committee FNL 7 “Optical Radiation” and a member of the DVGW Project Group on UV Disinfection.
