Lunar Lander Spacecraft - A Worked Example

Chemical rockets use up a majority of their mass getting to where they want to go. In this example, we start with a rocket delivered to low Earth orbit and fly it to the surface of the moon.

Start with the Rocket Equation:

delta_v = g * Isp * ln( Mo/Mf )
Mo/Mf = exp( delta_v/(g*Isp)

Mo = mass at the start of the burn
Mf = mass at the end of the burn
Fuel consumed = Mo - Mf
g = acceleration of gravity

(In whatever units you're using. I used 32.174 ft/sec^2 to go with delta_v in ft/sec.)

Isp = specific impulse of the rocket motor, in seconds

Given:

delta_v from LEO to lunar surface = 19,648 ft/sec
Isp = 350 sec (typical for hypergolic fuel)

Then:

Mo/Mf = 5.72

So, if your launcher can deliver 250,000 lbs to LEO, then you can land 250,000/572 = 43,670 lbs on the surface of the moon.