Abstract: The present invention relates to providing on-line tools for property-related on-line calculations. A distributed computer network can enable a user to access multiple databases and to obtain comparables data related to a property of interest for use in calculations. A user can access the latest, broadest set of relevant property data and to select relevant comparable values quickly and with minimal manual intervention. An on-line property management environment can comprise a distributed computer network coupled to numerous client computers, a property services server platform connected to a local data base, and numerous property information databases. A valuation tool, lease improvement calculator, refinancing calculator, capitalization rate calculator, mortgage and amortization calculator, and an affordability calculator can enable a user to make multiple property-related on-line calculations.