Convert Em to Light year
Unit definitions
Em
An em is a unit of typography equal to the point size of the font, commonly $12$ points or $\frac{1}{6}$ of an inch.
Light year
A light year is equal to the distance light travels in a Julian year ($365.25$ days). It is exactly $9\,460\,730\,472\,580\,800$ meters.
How to convert Em to Light year
$$\text{Length}_{\text{ly}} = \text{Length}_{\text{em}} \cdot 4.474636864037538796370049553653705e - 19$$
Examples
Example 1
Convert $40.0\ \text{em}$ to $\text{ly}$.
$$\text{Length}_{\text{ly}} = 40.0 \cdot 4.474636864037538796370049553653705e - 19$$
$$\text{Length}_{\text{ly}} = 0.00000000000000001789854745615015518548019821461482$$
$$\therefore \ 40.0\ \text{em} = 0.00000000000000001789854745615015518548019821461482 \ \text{ly}$$
Example 2
Convert $75.0\ \text{em}$ to $\text{ly}$.
$$\text{Length}_{\text{ly}} = 75.0 \cdot 4.474636864037538796370049553653705e - 19$$
$$\text{Length}_{\text{ly}} = 0.00000000000000003355977648028154097277537165240279$$
$$\therefore \ 75.0\ \text{em} = 0.00000000000000003355977648028154097277537165240279 \ \text{ly}$$
Example 3
Convert $100.0\ \text{em}$ to $\text{ly}$.
$$\text{Length}_{\text{ly}} = 100.0 \cdot 4.474636864037538796370049553653705e - 19$$
$$\text{Length}_{\text{ly}} = 0.00000000000000004474636864037538796370049553653705$$
$$\therefore \ 100.0\ \text{em} = 0.00000000000000004474636864037538796370049553653705 \ \text{ly}$$
Example 4
Convert $145.0\ \text{em}$ to $\text{ly}$.
$$\text{Length}_{\text{ly}} = 145.0 \cdot 4.474636864037538796370049553653705e - 19$$
$$\text{Length}_{\text{ly}} = 0.00000000000000006488223452854431254736571852797873$$
$$\therefore \ 145.0\ \text{em} = 0.00000000000000006488223452854431254736571852797873 \ \text{ly}$$
Example 5
Convert $160.0\ \text{em}$ to $\text{ly}$.
$$\text{Length}_{\text{ly}} = 160.0 \cdot 4.474636864037538796370049553653705e - 19$$
$$\text{Length}_{\text{ly}} = 0.00000000000000007159418982460062074192079285845928$$
$$\therefore \ 160.0\ \text{em} = 0.00000000000000007159418982460062074192079285845928 \ \text{ly}$$