Enter the speed of light and the speed of light in a medium, and this calculator will determine the index of refraction. The index fraction is calculated with the formula presented below. This formula is also known as **Snell’s Law.**

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## Index of Refraction Formula

The formula for calculating a refraction index is as follows:

n = c / v

- Where n is the index of refraction
- c is the speed of light in a vacuum = 299,792.46km/s
- v is the speed of light in a given medium

To calculate an index of refraction, divide the speed of light in a vacuum by the speed of light in the medium.

## Index of Refraction Definition

An index of refraction is the ratio of the speed of light through a vacuum with respect to the speed of light through some other medium, such as water.

## How to calculate index of refraction?

How to calculate index of refraction?

**First, determine the speed of light in a vacuum.**The speed of light in a vacuum is known to be 299,792.46 km/s.

**Next, measure the speed of light in the medium.**For example, the speed of light through water is 225,000.00 km/s.

**Finally, calculate the index of refraction.**Using the formula above and values from steps 1 and 2, calculate the index of refraction.

## FAQ

**What is an index of refraction?**

An index of refraction is the ratio of the speed of light through a vacuum with respect to the speed of light through some other medium, such as water.