Ummm, not sure tbh. I don't think they ever listed this on their website either. At a guess maybe 1.8l? There's no rigidity to it so you can stuff quite a lot in, deffo enough for a day ride. I've had tools, tube, softshell and some snacks in it. I'll take more pictures later.
Any idea what the litre capacity is on the saddle bag, and is it waterproof? Thanks,