How to obtain a luminosity from an SED

I have a spectral energy distribution (flux densities measured at several frequencies), and have fitted a 'greybody' model to these points.

I am confused about how I use this information to determine the luminosity of my source.

I think the integral of my fitted function gives me the total flux, but how is this related to the source's luminosity?

The luminosity is $$4\pi d^2$$ multiplied by the integral under your SED.
i.e. you cannot find the luminosity without knowing the distance $$d$$ to the source.
• @jm22b It depends how accurately you want the luminosity but $z\sim 3$ is large. You will have to work out the "luminosity distance" to use as $d$, which depends on cosmological parameters. en.wikipedia.org/wiki/Distance_measures_(cosmology) – ProfRob Jan 7 at 10:15