RedGrittyBrick covers incandescent lumens. For LED lumens on the cheapies, figure 60-100 lumens per watt.
A huge issue comparing them is that Incandescents and most other kinds light up an entire sphere, and those are the lumens they measure, even though we actually want a wedge or cone. Reflectors are not that efficient, so they waste a lot of their listed lumens. LEDs are directional and give light in typically a 140 degree cone. And that's still more than we actually want in most fixtures.
For instance I am under a downlight that emits about a 90 degree cone. Project that on a sphere (as the CFL is doing) and it's barely 10% of the surface area of that sphere. So 90% of the light is tossed into reflectors. I haven't run the numbers with a 140 degree arc, but it's many times better, and with lensing instead, near perfect.
For LED strips it generally means it gives you light exactly where you expect to get it, giving an LED lumen perhaps twice the punch of a lumen from any other source.
It gets even better when the LEDs are colored, because a native colored LED gives 100% of its lumens in the desired hue, whereas any other source there'll be a colored filter that blocks 2/3 of the lumens because they're the wrong hue.