I have a 15 led 0,5m led strip (ws2812b). Since it's such a limited amount of leds, I'll try to power the strip with an old phone power adapter (5v / 750mA). I looked at the ws2812's data sheet and it says
Each RGB LED draws approximately 50 mA at 5 V with red, green, and blue at full brightness
So that's 15 x 50mA = 750mA
I'll call that one tight, but won't it be all right because these leds are never gonna run full power all the time.