Top: (Left) Combined-light, unresolved and (Right) differential, resolved photometry for GJ 3305 AB (black) compared to predictions (red) of the BHAC15 models as a function of age given the observed masses and parallax. The data are consistent with an age larger than 25 Myr. Plotted bars along the abscissa correspond to the width of each filter and are meant to guide the eye: they do not represent an uncertainty. (Middle left) SED for the system, assuming a 24 ± 3 Myr age and the observed masses. Combined-light photometry is in black and resolved photometry in purple. While the model accurately reproduces the observed flux from GJ 3305 A, it overpredicts the received flux from GJ 3305 B. (Middle right) Joint posterior probability distributions on the masses of the two stars, (black) inferred from the astrometry and RV data and (red) predicted by the BHAC15 models given the observed combined-light and differential photometry assuming an age of 24 ± 3 Myr. Contours correspond to the 1, 2, and 3σ confidence regions. The BHAC15 models predict a mass for GJ 3305 B consistent with the mass inferred from the data, but underpredicts the mass of GJ 3305 A by 20%. (Bottom left) CMD showing the absolute H magnitudes and H − K colors of GJ 3305 AB compared to theoretical models. The models provide a more accurate fit for GJ 3305 A than GJ 3305 B. (Bottom right) Posterior probability distribution on the age of the GJ 3305 system, calculated by marginalizing the joint mass-age posterior over all allowed masses, assuming both stars are the same age. The BHAC15 models predict an age of 37 ± 9 Myr; the dashed line represents the Bell et al. (2015) age of the β Pictoris system.