I have been looking into buying a high powered laser and I just want to know what is stronger a 20 mW 473nm Blue Laser or a 200-300 mW 532nm Green Laser (200 or 300 mW)

The higher the mW (milliWatts), the higher the power of the laser. So the answer is the green laser.

Green is also more visible to humans than blue, so it will appear brighter at the same power output.

BhavinB yes the higher the milliWatts the more power but wavelength also

makes a difference. (Example: 1 mw of red 670 nm will look weaker than of blue 473nm there for milliWatt by milliWatt blue will be stronger. By how much I dont know) if I had a 300 mw green laser and a 300 mn blue laser the blue would be stronger but I need to know by how much. It could be 1.5 times but it also could be 20 times and to what Sisyphus said I have heard that before but by how much are we more sensitive

Sisyphus only said it might appear stronger. But when it comes down to POWER as your question asked, the measure is mW (If the method of characterization is your eye, then you don't even need 5 mW to damage someones sight let alone 300 mW)

 

Compare this to the age old question...what weighs more? 100kg of rocks or 100kg of feathers.

I understand now thanks (and I am going to buy the green one)