This page gathers a lot of formulas to calculate waveguide wavelength, cutoff wavelength and attenuation. These formulas are only applicable for dominant mode.
notes:
maximum peak power is limited by voltage arc threshold (30 kV/cm in dry air), usually the safety factor is two
maximum cw power is limited by waveguide heating due to losses in the waveguide walls
rectangular waveguides have the greatest usably frequency range, followed by square, then round guides
http://df2ck.de/tech/wg/
