RGB controller spec sheet, what do the watts mean?

[ate_mae]

Sign client wants color-changing logo, 5 meters of WS2812B RGB strip. Looking at controllers.

Datasheets confuse me:

• Controller says "100W max load"
• Strip says "18W/meter at full white"

So 5m strip * 18W = 90W. Within 100W controller, OK?

Or should I add 20% safety, meaning I need 110W+ controller? Or does "100W" already include safety margin?

Sign veterans: what derating do you actually use? Lost one PSU last month, suspicious it was running at 95% load 24/7.