Many materials have a well-characterized refractive index, but these indices often depend strongly upon the frequency of light, causing optical dispersion. Standard refractive index measurements are taken at the "yellow doublet" sodium D line, with a wavelength (λ) of 589 nanometers.

There are also weaker dependencies on temperature, pressure/stress, etc., as well on precise material compositions (presence of dopants, etc.); for many materials and typical conditions, however, these variations are at the percent level or less. Thus, it's especially important to cite the source for an index measurement if precision is required.

In general, an index of refraction is a complex number with both a real and imaginary part, where the latter indicates the strength of absorption loss at a particular wavelength—thus, the imaginary part is sometimes called the extinction coefficient ${\displaystyle k}$. Such losses become particularly significant, for example, in metals at short (e.g. visible) wavelengths, and must be included in any description of the refractive index.

## List

Some representative refractive indices
Name of material λ (nm) Refractive index no. n Reference
Vacuum 1 (by definition)
Air at STP 1.000273 [citation needed]
Gases at 0 °C and 1 atm
Air 589.29 1.000293 [1]
Carbon dioxide 589.29 1.00045 [2][3][4]
Helium 589.29 1.000036 [1]
Hydrogen 589.29 1.000132 [1]
Liquids at 20 °C
Arsenic trisulfide and sulfur in methylene iodide 1.9 [5]
Carbon disulfide 589.29 1.628 [1]
Benzene 589.29 1.501 [1]
Carbon tetrachloride 589.29 1.461 [1]
Silicone oil (nD25) 589.29 1.393–1.403 [6]
Kerosene 1.39
Ethanol (ethyl alcohol) 589.29 1.361 [1]
Acetone 1.36
Water 589.29 1.333 [1]
10% glucose solution in water 589.29 1.3477 [7]
20% glucose solution in water 589.29 1.3635 [7]
60% glucose solution in water 589.29 1.4394 [7]
Solids at room temperature
Silicon carbide (moissanite; 6H form) 589.29 2.65 [8]
Titanium dioxide (rutile phase) 589.29 2.614 [9][10]
Diamond 589.29 2.417 [1]
Strontium titanate 589.29 2.41 [11]
Tantalum pentoxide 589.29 2.15 [12]
Amber 589.29 1.55 [1]
Sodium chloride 589.29 1.544 [13]
Fused silica (a pure form of glass, also called fused quartz) 589.29 1.458 [1][14]
Other materials
Liquid helium 1.025
Perfluorohexane (Fluorinert FC-72) 1.251 [15]
Water ice 1.31
TFE/PDD (Teflon AF) 1.315 [16][17]
Cryolite 1.338
Cytop 1.34 [18]
Polytetrafluoroethylene (Teflon) 1.35–1.38 [19]
Sugar solution, 25% 1.3723 [20]
Cornea (human) 1.373/1.380/1.401 [21]
Lens (human) 1.386–1.406
Liver (human) 964 1.369 [22]
Intestinal mucosa (human) 964 1.329–1.338 [23]
Ethylene tetrafluoroethylene (ETFE) 1.403 [24]
Sylgard 184 (polydimethylsiloxane) 1.4118 [25]
Sugar solution, 50% 1.4200 [20]
Polylactic acid 1.46 [26]
Pyrex (a borosilicate glass) 1.470 [27]
Vegetable oil 1.47 [28]
Glycerol 1.4729
Sugar solution, 75% 1.4774 [20]
Poly(methyl methacrylate) (PMMA) 1.4893–1.4899
Halite (rock salt) 1.516
Plate glass (window glass) 1.52
Crown glass (pure) 1.50–1.54
PETg 1.57
Polyethylene terephthalate (PET) 1.5750
Polycarbonate 150 1.60 [30]
Crown glass (impure) 1.485–1.755
Flint glass (pure) 1.60–1.62
Bromine 1.661
Flint glass (impure) 1.523–1.925
Sapphire 1.762–1.778
Boron nitride 2–2.14 [31]
Cubic zirconia 2.15–2.18 [32]
Potassium niobate (KNbO3) 2.28
Zinc oxide 390 2.4
Cinnabar (mercury sulfide) 3.02 Birefringent: nω = 2.905 nε = 3.256[33]
Silicon 1200 - 8500 3.42–3.48 [34]
Gallium(III) phosphide 3.5
Gallium(III) arsenide 3.927
Germanium 3000 - 16000 4.05–4.1 [35]

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