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| Material | εr |
| Vacuum | 1 (by definition) |
| Air | 1.00058986 ± 0.00000050 (at STP, for 0.9 MHz),[1] |
| PTFE/Teflon | 2.1 |
| Polyethylene | 2.25 |
| Polyimide | 3.4 |
| Polypropylene | 2.2–2.36 |
| Polystyrene | 2.4–2.7 |
| Carbon disulfide | 2.6 |
| Mylar | 3.1[2] |
| Paper | 3.85 |
| Electroactive polymers | 2–12 |
| Mica | 3-6[2] |
| Silicon dioxide | 3.9 [3] |
| Sapphire | 8.9–11.1 (anisotropic) [4] |
| Concrete | 4.5 |
| Pyrex (Glass) | 4.7 (3.7–10) |
| Neoprene | 6.7[2] |
| Rubber | 7 |
| Diamond | 5.5–10 |
| Salt | 3–15 |
| Graphite | 10–15 |
| Silicon | 11.68 |
| Ammonia | 26, 22, 20, 17 (−80, −40, 0, 20 °C) |
| Methanol | 30 |
| Ethylene glycol | 37 |
| Furfural | 42.0 |
| Glycerol | 41.2, 47, 42.5 (0, 20, 25 °C) |
| Water | 88, 80.1, 55.3, 34.5 (0, 20, 100, 200 °C) for visible light: 1.77 |
| Hydrofluoric acid | 83.6 (0 °C) |
| Formamide | 84.0 (20 °C) |
| Sulfuric acid | 84–100 (20–25 °C) |
| Hydrogen peroxide | 128 aq–60 (−30–25 °C) |
| Hydrocyanic acid | 158.0–2.3 (0–21 °C) |
| Titanium dioxide | 86–173 |
| Strontium titanate | 310 |
| Barium strontium titanate | 500 |
| Barium titanate | 1250–10,000 (20–120 °C) |
| Lead zirconium titanate | 500–6000 |
| Conjugated polymers | 1.8–6 up to 100,000[5] |
| Calcium copper titanate | >250,000[6] |
The relative permittivity of a material is its dielectric permittivityexpressed as a ratio relative to the permittivity of vacuum.
Permittivity is a material property that expresses the force between two point charges in the material. Relative permittivity is the factor by which the electric field between the charges is decreased or increased relative to vacuum.
Likewise, relative permittivity is the ratio of the capacitance of acapacitor using that material as a dielectric, compared to a similar capacitor that has vacuum as its dielectric. Relative permittivity is also commonly known as dielectric constant, a term deprecated in physics and engineering.
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