Refractive index to speed of light in it
Type a value in n to get it in km/s instantly.
199,861.6km/s
That's 1.13× as dense as water, while window glass is 1.01× higher. Light travels 1.5 times slower inside it.
Convert the other way: km/s to n
What it means
How much does it bend light?
Index depends on wavelength — that is what makes a prism work. Published values are usually for the yellow sodium line at 589 nm.
The math
How to convert n to km/s
From the index: the speed inside is c ÷ n, the critical angle is arcsin(1 ÷ n), Brewster’s angle is arctan(n), and the head-on reflectance is ((n − 1) ÷ (n + 1))².
Example: 1.5 n = 199,862 km/s.
Every unit
Your index in every unit
Tables
n to km/s conversion table
| n | km/s |
|---|---|
| 1.0003 n | 299,703 km/s |
| 1.2 n | 249,827 km/s |
| 1.31 n | 228,849 km/s |
| 1.33 n | 225,408 km/s |
| 1.46 n | 205,337 km/s |
| 1.5 n | 199,862 km/s |
| 1.6 n | 187,370 km/s |
| 1.77 n | 169,374 km/s |
| 2 n | 149,896 km/s |
| 2.42 n | 123,881 km/s |
| 3.4 n | 88,174.3 km/s |
km/s to n conversion table
| km/s | n |
|---|---|
| 88,200 km/s | 3.39901 n |
| 124,000 km/s | 2.41768 n |
| 150,000 km/s | 1.99862 n |
| 169,000 km/s | 1.77392 n |
| 187,000 km/s | 1.60317 n |
| 200,000 km/s | 1.49896 n |
| 205,000 km/s | 1.4624 n |
| 225,000 km/s | 1.33241 n |
| 229,000 km/s | 1.30914 n |
| 250,000 km/s | 1.19917 n |
Quick answers
Quick answers
- How many km/s is 1 n?
- 1 n is 299,792 km/s.
- How many km/s is 10 n?
- 10 n is 29,979.2 km/s.
- How many km/s is 1.5 n?
- 1.5 n is 199,862 km/s.
The units
About these units
Refractive index (n)
How many times slower light travels in the material.
Speed of light in it (km/s)
The actual speed inside, in kilometers per second.
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