There's more to it than wattage though, it's not a reliable baseline to maintain familiarity.
I can build a coil with 28g Ka, or with 22g Ka, or with 2 or 4 strands twisted together and get them all to the same resistance by altering the size of core and number of turns - and if I run them at the same wattage they'll perform entirely differently...
And that's before you get into how it's wicked and the placement in the airflow.
While this might appear like I'm trying to make it sound complicated, I'm actually just trying to temper expectations.
Throwing in a build of the same resistance (ohms) as a stock coil and expecting it to perform the same if the wattage is set the same is (imo) what causes a lot of people to condemn rebuildables.
(If I wanted to make it complicated I'd explain how there's no such thing as variable wattage anyway
)