Welcome to Fly Near Space. Here you will find several calculators for gas-lifted airships. These work on zeppelins, balloons, inflated trash bags, and anything else you use a lighter than air gas to fly. From my experence these aren't readibly available calculators and it took many months of reseach and understanding for me to actually make use of them. I hope you enjoy them and it makes flight planning much easier!
While these calculators are mathmatically accurate, they only represent ideal environmental conditions. Gases aren't perfectly pure, balloons aren't perfectly round, and the winds are relentless. Just make sure you have plenty of lift and you will be smiling on launch day!