  Ultracool dwarfs have emerged as key targets for searches of transiting
exoplanets. Precise estimates of the host parameters (including mass, age, and
radius) are fundamental to constrain the physical properties of orbiting
exoplanets. We have extended our evolutionary code CLES (Code Li\'egeois
d'Evolution Stellaire) to the ultracool dwarf regime. We include relevant
equations of state for H, He, as well as C and O elements to cover the
temperature-density regime of ultracool dwarf interiors. For various
metallicities, we couple the interior models to two sets of model atmospheres
as surface boundary conditions. We show that including C and O in the EOS has a
significant effect close the H-burning limit mass. The typical systematic error
associated with uncertainties in input physics in evolutionary models is $\sim
0.0005 M_\odot$. We test model results against observations for objects whose
parameters have been determined from independent techniques. We are able to
reproduce dynamical mass measurements of LSPM J1314+1320AB within $1\sigma$
with the condition of varying the metallicity (determined from calibrations) up
to $2.5\sigma$. For GJ 65AB, a $2\sigma$ agreement is obtained between
individual masses from differential astrometry and those from evolutionary
models. We provide tables of ultracool dwarf models for various masses and
metallicities that can be used as reference when estimating parameters for
ultracool objects.

Solar and Stellar Astrophysics;Earth and Planetary Astrophysics