  The Kepler Eclipsing Binary Catalog (KEBC)describes 2165 eclipsing binaries
identified in the 115 deg^2 Kepler Field based on observations from Kepler
quarters Q0, Q1, and Q2. The periods in the KEBC are given in units of days out
to six decimal places but no period errors are provided. We present the PEC
(Period Error Calculator) algorithm which can be used to estimate the period
errors of strictly periodic variables observed by the Kepler Mission. The PEC
algorithm is based on propagation of error theory and assumes that observation
of every light curve peak/minimum in a long time-series observation can be
unambiguously identified. The PEC algorithm can be efficiently programmed using
just a few lines of C computer language code. The PEC algorithm was used to
develop a simple model which provides period error estimates for eclipsing
binaries in the KEBC with periods less than 62.5 days. KEBC systems with
periods >=62.5 days have KEBC period errors of about 0.0144 days. Periods and
period errors of 7 eclipsing binary systems in the KEBC were measured using the
NASA Exoplanet Archive Periodogram Service and compared to period errors
estimated using the PEC algorithm.
