Relative permittivity (dielectric constant) to velocity factor
Type a value in εr to get it in VF instantly.
0.4767VF
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: VF 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 VF
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 = 0.476731 VF.
Every unit
Your permittivity in every unit
Tables
εr to VF conversion table
| εr | VF |
|---|---|
| 1 εr | 1 VF |
| 1.5 εr | 0.816497 VF |
| 2 εr | 0.707107 VF |
| 2.1 εr | 0.690066 VF |
| 3 εr | 0.57735 VF |
| 4 εr | 0.5 VF |
| 4.4 εr | 0.476731 VF |
| 6 εr | 0.408248 VF |
| 10 εr | 0.316228 VF |
| 20 εr | 0.223607 VF |
| 50 εr | 0.141421 VF |
| 80 εr | 0.111803 VF |
VF to εr conversion table
| VF | εr |
|---|---|
| 0.112 VF | 79.7194 εr |
| 0.141 VF | 50.2993 εr |
| 0.224 VF | 19.9298 εr |
| 0.316 VF | 10.0144 εr |
| 0.408 VF | 6.0073 εr |
| 0.477 VF | 4.39504 εr |
| 0.5 VF | 4 εr |
| 0.577 VF | 3.00364 εr |
| 0.69 VF | 2.1004 εr |
| 0.707 VF | 2.0006 εr |
| 0.816 VF | 1.50183 εr |
| 1 VF | 1 εr |
Quick answers
Quick answers
- How many VF is 1 εr?
- 1 εr is 1 VF.
- How many VF is 10 εr?
- 10 εr is 0.316228 VF.
- How many VF is 4.4 εr?
- 4.4 εr is 0.476731 VF.
The units
About these units
Relative permittivity (dielectric constant) (εr)
Compared with a vacuum, which is exactly 1.
Velocity factor (VF)
Signal speed in a cable filled with it, as a fraction of c.
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