  The PLATO mission is scheduled for launch in 2026. This study aims to
estimate the number of exoplanets that PLATO can detect as a function of
planetary size and period, stellar brightness, and observing strategy options.
Deviations from these estimates will be informative of the true occurrence
rates of planets, which helps constraining planet formation models. For this
purpose, we developed the Planet Yield for PLATO estimator (PYPE), which adopts
a statistical approach. We apply given occurrence rates from planet formation
models and from different search and vetting pipelines for the Kepler data. We
estimate the stellar sample to be observed by PLATO using a fraction of the
all-sky PLATO stellar input catalog (PIC). PLATO detection efficiencies are
calculated under different assumptions that are presented in detail in the
text. The results presented here primarily consider the current baseline
observing duration of four years. We find that the expected PLATO planet yield
increases rapidly over the first year and begins to saturate after two years. A
nominal (2+2) four-year mission could yield about several thousand to several
tens of thousands of planets, depending on the assumed planet occurrence rates.
We estimate a minimum of 500 Earth-size (0.8-1.25 RE) planets, about a dozen of
which would reside in a 250-500d period bin around G stars. We find that
one-third of the detected planets are around stars bright enough (V $\leq 11$)
for RV-follow-up observations. We find that a three-year-long observation
followed by 6 two-month short observations (3+1 years) yield roughly twice as
many planets as two long observations of two years (2+2 years). The former
strategy is dominated by short-period planets, while the latter is more
beneficial for detecting earths in the habitable zone.
