Hourly billing sounds fair in theory — you only pay for time actually worked — but in practice it quietly shifts all the risk of scope misunderstanding onto the client.
The misaligned incentive
Under hourly billing, more hours worked means more revenue for the agency, regardless of whether those hours were spent efficiently. That’s not usually bad faith — it’s just a structure where nobody has to get the estimate right up front, because going over doesn’t cost the agency anything.
What fixed-price actually requires
A fixed-price quote forces a real scoping conversation before work starts: what exactly is being built, what’s explicitly out of scope, what happens if requirements change partway through. That conversation is uncomfortable to skip under hourly billing and unavoidable under fixed-price — which is exactly why it produces a clearer, more accurate project in the first place.
Where hourly still makes sense
Ongoing maintenance, exploratory work where the scope genuinely can’t be known in advance, or a long-term staff augmentation arrangement — these are legitimately open-ended, and hourly or retainer billing fits them better than forcing a fixed price onto work that doesn’t have a fixed shape.
The real question to ask
Not “which pricing model is cheaper” but “which pricing model gives the people building this a reason to scope it accurately.” For anything with a defined deliverable — a website, an app, an integration — that’s almost always fixed-price.