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This is not a question about which is cheaper. It is a question about who carries the risk of the unknown parts, and the honest answer depends entirely on how well the product can be described before work begins. Pick the wrong model and the contract works against both sides for months.
Fixed price when the product can be described in writing before work starts, because then the scope list protects both sides. Hourly when the product is still finding its shape and priorities change between sprints, because then a fixed price is either padded or quietly narrowed. If the scope cannot be described yet, neither model is right and a short paid scoping engagement comes first.
In a fixed price contract the supplier carries the risk of the unknown, and charges for carrying it. In an hourly contract you carry it, and pay only for what happens. That single sentence explains every other difference between the two, including why a fixed price is never the cheapest possible outcome and why hourly work never comes with a guaranteed total.
Certainty about the total, and someone else's problem if the work turns out harder than expected. You pay a premium for that, and the premium is the honest part of the arrangement.
Flexibility and no premium. You pay for the work that happens, including the parts that were never predicted, and you can change direction without renegotiating a contract.
Certainty about what the product should be. That comes from scoping, and no contract shape substitutes for it.
The models look similar in a proposal and behave completely differently the moment reality arrives. Five situations that occur in most projects, and what each model does with them. Read them as the actual product you are buying, because this is where the difference is felt rather than in the rate.
It is estimated, you decide whether it goes into this release or the next, and it is recorded as a change. The original price and date stay intact, and the addition is visible.
It is simply built, and appears later as hours on an invoice. Faster, but the total moves without anyone deciding that it should.
The supplier absorbs it, because the price is theirs to hold. That is what the risk premium in the number was for, and it is the main reason a fixed price is not the cheapest possible arrangement.
You absorb it, in hours. The estimate was always an estimate, and this is exactly the case it did not cover.
Painful. The scope was the contract, so a genuine direction change means renegotiating rather than adjusting, and the earlier work may not survive it.
Normal. This is the case hourly billing exists for, and treating it as failure is what pushes people into the wrong model in the first place.
Their cost, not yours. The date and the price were quoted against a written scope, and slipping it is the supplier's problem to solve.
Your cost, unless the contract says otherwise. Ask what happens to the rate and the estimate when the original hours are exhausted.
Complicated. Fixed price contracts are written around a delivered outcome, so ending mid way means agreeing what was completed and what it was worth.
Straightforward. You stop paying for hours that have not been worked, which is the clearest advantage of the model and rarely mentioned.
When the scope cannot be described without guessing. Then the number protects neither side: either it is padded to cover the unknowns and you overpay, or it is held by narrowing what gets built, which you discover late. A supplier quoting a firm price from a one page brief is telling you something about how the project will run.
A number produced from that is a guess dressed as a commitment. Ask what the estimate assumes, and watch whether a list exists.
A fixed price without a written boundary is a fixed price for something that has not been agreed. The exclusions are what make the number mean anything.
If the point of the next three months is to learn what the product should be, a fixed scope contract fights the work rather than supporting it.
The same logic applies in reverse. Hourly billing on a project that could have been fully specified means you are carrying risk you did not need to carry, and paying for it in uncertainty rather than in a premium.
Yes, and for many projects it is the right answer. The two models are usually presented as a choice, but the useful arrangements combine them across the life of a project.
The pattern we use most often is a short paid scoping engagement, then a fixed price for the defined first version, then hourly work for whatever the product needs once real users are in it. Each phase gets the model that is honest for it.
Figures and package shapes are on the pricing page, and the reasoning behind fixed scope contracts is in our guide to fixed price app development.
We are a mobile development team in Krakow, Poland, building Flutter and React Native products for companies in the United States and Europe. Most of our contracts are fixed scope and fixed price, and we say so when a project should not be one, which happens often enough that it is worth publishing.
Quoted against a written scope list with exclusions, closing with a signed acceptance protocol and a one year warranty on larger contracts.
End to end app development Continuous workFor products developed iteratively, where priorities change between sprints and that change is the point rather than a problem.
Hire Flutter developers Unknown codeOn takeovers we audit first, because any fixed price offered before seeing the codebase would be invented rather than estimated.
App rescue and takeoverUsually yes in the best case and cheaper in the worst case, which is the whole point. You are paying a premium for someone else to carry the risk of the unknown. If everything goes smoothly, hourly would have cost less. If it does not, the fixed price holds.
Agree a ceiling with a checkpoint before it is reached, ask for a short written summary at the end of each sprint, and keep a prioritised list so the hours go to what matters most. Hourly work goes wrong through absent direction rather than through the model itself.
The change is estimated, you decide whether it goes into this release or the next one, and it is recorded in writing. That keeps both the original price and the original date meaningful. What damages a project is a supplier absorbing changes silently and explaining a delay afterwards.
You can get a number. Whether it means anything depends on how much guessing went into it. If a supplier can quote firmly from a short brief, ask what the estimate assumes and what is excluded, and judge the answer rather than the speed.
Fixed price, in most cases, because a first version should be tightly bounded and the boundary is the point. If you cannot yet say what the first version proves, that is a scoping problem rather than a pricing one. More on MVP development.
It should include fixing anything agreed inside the scope that does not work, under a stated warranty period. It does not include new features, which are quoted separately. Running costs are a different subject, covered in our guide to app maintenance cost.
Tied to delivery rather than to the calendar. Milestones with something you can install or review at each one keep both sides honest, and they give you a natural point to stop if the work is not what you expected.
I will tell you whether it can be scoped tightly enough for a fixed price, and if it cannot, what shape would actually be fair to you.
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