I'll skip past the various formulas and make note that while the LEDs cost more right now, they don't give off heat, they don't burn out, and there are some absolutely beautiful lamps made from them. I have several around the house that are enough to navigate by at night. Some are rechargeable (with built-in batteries) and others have adapters.

For a fixture on the ceiling it would take a lot of LED bulbs to amount to anything, which might weigh more than you like. Why not skip the ceiling fixture and go with lamps around the room from wall plugs, and make some of them LEDs and the energy efficient fluorescent or very-efficient-for-the-wattage halogens?

SRS