Calculating a planet's mass & gravitational pull

[dogscoff]

1 cubic kilometer = 1,000,000,000 cubic meters (i.e. 1000^3 cubic meters)

Aha! So if I multiply the result by 1000000000... Yes, i get a value for Earth & Mars masses that (more or less) matches what I find on websites. Excellent, thanks, slick.

Yes, 10^-11 means move the decimal 11 places to the left.

OK, I'll plug that in.

The kg-1 and s-2 refer to exponents in this limited UBB system. Negative means in the denominator, so the units would be: m^3 / [kg x s^2]

Ummm... I didn't understand any of that. Sorry, can you put it into language that can be understood by someone of my high mean density?

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Tomorrow I'm going to have a go at putting all of this functionality into java so I can offer it on my website.
Planned features:
-flexible input values (ie it can automatically calculate circumference from diameter or vice versa.)
-Side by side comparison with a selectable "benchmark" planet (Earth, Mars, Jupiter, Plenty... any others I should have?
-Choose between raw data comparison or proportional comparison (ie Planet X has 125% earth's land surface area)
-Variable input units (miles or kilometres etc)

Anyone likely to use this? I doubt it will see a lot of usage, but thought it might be a handy toy for sci-fi writers. Any particular features I ought to implement? Even if no-one wants it I'll do it anyway as a programming excercise for myself.