Enter stellar effective temperature and luminosity (Default is Sun).
If you don't know the luminosity, just enter Teff and keep luminosity = 0.
That will give you just Habitable stellar flux boundaries.
(If you want to calculate HZs for a number of stars, download this fortran code)
After entering the values in each box, just click inside each box to obtain the results.
Runaway Greenhouse limit
If you use this calculator or the FORTRAN code, please cite the following publication:
"Habitable Zones Around Main-Sequence Stars: New Estimates" by Kopparapu et al.(2013), Astrophysical Journal, 765, 131    arXiv link