  We derive the radii of 16 brown dwarfs observed by AKARI using their
parallaxes and the ratios of observed to model fluxes. We find that the brown
dwarf radius ranges between 0.64-1.13 RJ with an average radius of 0.83 RJ. We
find a trend in the relation between radii and Teff; the radius is at a minimum
at Teff~1600 K, which corresponds to the spectral types of mid-to late-L. The
result is interpreted by a combination of radius-mass and radius-age relations
that are theoretically expected for brown dwarfs older than 10^8 yr.
