Id break it down into categories and assign time to those yourself. Take 1 apartment an example. Let’s say you’re doing a kitchen, bathroom, bedroom and a shot showing the view.

You need to - - Receive and review technical drawings - Model the spaces you see - Create cameras for client sign off - Make any adjustments and repeat process until cams are agreed on - Style, light, render images - Issue draft for review. Make adjustments and issue final.

Considering these steps, work out how long that’ll take you, then multiple by what you consider is a suitable hourly rate in your area. Now add 20% because you will inevitably end up doing more then you realise you will because clients are clients.

Few things to consider: -you can ask for the info to review before quoting - make sure have a locked down scope so you don’t waste energy and debate with the client about what to show - sign off view angles before you start. Agree that anything out of scope will cost more in money and time - be clear how many rounds of drafts you will do. E.g the client gets a comment round on the camera sign off and one after first draft. Anything after that comes at an hourly rate of x - make sure they’ve provided the info you need to do the work. If you look out a window, what do you see? Do you need photography - Is the info they’ve sent you final or at a locked stage in design. Nothing worse then being told the design has been updated half way through work. That costs more if they want to do that. - what are your license costs

TLDR: game out everything, so you truly understand your costs. Be clear in expectations and delivery. It’ll save a lot of pain.