Relative permittivity (dielectric constant) to refractive index (non-magnetic)
Type a value in εr to get it in n instantly.
2.098n
That's about the same as FR-4 circuit board. A signal in it travels at about 47.67% of the speed of light.
Convert the other way: n to εr
What it means
How strongly does it polarize?
Values are typical at low frequency and room temperature. Water’s permittivity falls sharply at microwave frequencies, which is how microwave ovens heat it.
The math
How to convert εr to n
Absolute permittivity is ε = εr × 8.854 pF/m. For a non-magnetic material the refractive index is √εr, and a cable’s velocity factor is 1 ÷ √εr.
Example: 4.4 εr = 2.09762 n.
Every unit
Your permittivity in every unit
Tables
εr to n conversion table
| εr | n |
|---|---|
| 1 εr | 1 n |
| 1.5 εr | 1.22474 n |
| 2 εr | 1.41421 n |
| 2.1 εr | 1.44914 n |
| 3 εr | 1.73205 n |
| 4 εr | 2 n |
| 4.4 εr | 2.09762 n |
| 6 εr | 2.44949 n |
| 10 εr | 3.16228 n |
| 20 εr | 4.47214 n |
| 50 εr | 7.07107 n |
| 80 εr | 8.94427 n |
n to εr conversion table
| n | εr |
|---|---|
| 1 n | 1 εr |
| 1.5 n | 2.25 εr |
| 2 n | 4 εr |
| 2.1 n | 4.41 εr |
| 3 n | 9 εr |
| 4 n | 16 εr |
| 4.4 n | 19.36 εr |
| 6 n | 36 εr |
| 10 n | 100 εr |
| 20 n | 400 εr |
| 50 n | 2,500 εr |
| 80 n | 6,400 εr |
Quick answers
Quick answers
- How many n is 1 εr?
- 1 εr is 1 n.
- How many n is 10 εr?
- 10 εr is 3.16228 n.
- How many n is 4.4 εr?
- 4.4 εr is 2.09762 n.
The units
About these units
Relative permittivity (dielectric constant) (εr)
Compared with a vacuum, which is exactly 1.
Refractive index (non-magnetic) (n)
The square root of εr at the same frequency.
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