how to measure power laser

hello
Recently i bought a green laser 200mW.i m having suspicions that its lower mW.how can i test it practicaly or visualy without the propriate electronic equipment?

Try focusing the beam with a magnifying glass to see it will burn stuff, if it does it is probably more than 50mw (although, if it isn't filtered, it may be the IR that does the burning rather than the green beam).

Other than that you can only compare output with something like a 5mw....

Regards rog8811