Stack Overflow says:

EV Lux
-1 1.25
-0.5 1.75
0 2.50
0.5 3.50
1 5.00
1.5 7.00
2 10.00
2.5 14.00
3 20.00
3.5 28.00
4 40.00
1 EV is 5 Lux. 2 EV is 10 Lux. 3 EV is 20 Lux. Hmmm. It looks logarithmic:

lux = (2 ^ ev) * 2.5;
(2 to the power of EV, times 2.5)
See also the Wikipedia article.

You can also use Wolfram Alpha, which, e.g., confirms the above math by calculating 10 EV to be 2560 lux.