Fixed price shifts estimation risk to the vendor and suits well-defined scope such as marketing sites and migrations. Time and materials shifts it to you and suits exploratory product work. Most successful engagements are hybrid: fixed price for a discovery phase, then time and materials or fixed-scope increments for the build.
Neither model prevents a project going wrong. What prevents it is a scope document both sides agree on — the contract only decides who pays when the estimate is wrong.
Bears risk on fixed price
Bears risk on T&M
What usually works
What actually matters
One number agreed upfront. Predictable for you, and the vendor absorbs a bad estimate.
You pay for hours worked. Flexible, and you carry the cost if it takes longer than hoped.
Hourly with a ceiling. Flexibility with a worst case, though vendors price the cap in.
Fixed monthly capacity, scope set per cycle. Best for continuous work with a shifting roadmap.
Fixed price split into staged payments tied to deliverables. Common and sensible for builds.
A small fixed-price phase producing the specification that makes the main estimate honest.
| Fixed price | Time & materials | |
|---|---|---|
| Who bears estimate risk | Vendor | Client |
| Budget predictability | High | Low without a cap |
| Flexibility to change | Low — change requests | High |
| Vendor incentive | Finish efficiently | Bill hours |
| Needs upfront definition | Yes, extensively | Less |
| Best for | Sites, migrations, defined builds | Product development, R&D |
| Common failure | Under-scoped bid, then change requests | Scope drift, budget creep |
This gives you a predictable number for the part that can be defined, and flexibility for the part that cannot. It is how most of our engagements run.
Time and materials is usually cheaper when things go well, because fixed price includes a risk premium. Fixed price is cheaper when they do not. You are effectively buying insurance against the estimate being wrong.
Yes, as fixed-scope increments: a fixed price per two-week cycle with scope agreed at the start of each. You get budget predictability and the ability to change direction between cycles.
Yes. It keeps the incentive honest — a vendor doing free discovery needs to win the build to recover the cost, which biases the recommendation. Paid discovery means they can tell you not to proceed.
Ask what is excluded and what happens if they are wrong. A low bid with vague scope almost always means change requests later. Compare scope line by line rather than comparing headline numbers.
Comparison
A 30-minute call, then a written proposal with scope, price and timeline within two to three working days. No retainer required to get a real number, and no obligation if the answer is that we are not the right fit.