How to convert LDR reading to lux readings?

I want to make a digital lux meter using a arduino but I am quiet confused on how do I convert LDR reading into lux reading.Please help me for the conversions. 

By calibration against a known good lux meter, or from a suitable reference source.
Bot1398 (author)  steveastrouk5 years ago
I dont own a lux meter
Borrow one. I didn't say you needed to own one.

If you can use a TAOS sensor, they could be a better place to start than a photodiode.

And what range do you want to cover ?