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Free Tool · Contract Model Chooser

Fixed price or time and materials?

Both models are sold as the safe choice. Answer four questions about your scope, budget, timeline and vendor, and this tool gives you a clear verdict with the reasoning, not just an answer.

Quick Answer

Fixed price fits a project with a written, unlikely-to-change spec and a hard budget ceiling. Time and materials fits a project with evolving requirements. A not-to-exceed cap on time and materials often beats pure fixed price when the scope is mostly, but not fully, settled - it gives you the ceiling of fixed price without the change-order spiral that happens when a locked price meets a scope that moves.

Contract Chooser

Answer four questions about your project

1. Is the scope written down and unlikely to change?

2. Do you need a guaranteed budget ceiling?

3. Is your timeline fixed or flexible?

4. New vendor, or an existing trusted one?

Your verdict

Time & materials with a not-to-exceed cap

Hourly billing, with a hard dollar ceiling written into the contract.

Minor changes are already expected, so a pure fixed price is likely to trigger at least one change order — put a not-to-exceed cap on hourly billing instead, so you keep a ceiling without renegotiating the whole contract for small changes.

What to put in your contract either way

  • The scope of work in writing, signed by both sides
  • Payment tied to milestones, not a single upfront payment
  • The change-order process and rate, agreed before you sign
  • A not-to-exceed cap written into the hourly rate
  • Who owns the code and the accounts at handover

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Next step

Already have quotes under a contract model?

Check them against realistic market rates before you sign. The Quote Analyzer scores 3 to 5 quotes and flags the patterns that wreck projects under either pricing model: lowball pricing, vague change-order terms, no warranty, full payment upfront.

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The real cost of picking the wrong model

From our project files

Brooklyn law firm — the fixed-price change-order spiral

$24,000 fixed price · +$9,500 change orders · $33,500 vs $20,500 T&M

What drove the cost

  • Three weeks in, the client added a custom intake form, multilingual support, and a member portal — every change order is a renegotiation, often at 130-180% of the original rate
  • Vendors price fixed-price work at 115-125% of expected T&M cost to cover their risk
  • Same vendor, same scope, $13,000 apart — the pricing model made the difference, not the work

What to demand in the quote

  • The change-order rate in writing before signing — this is where fixed-price projects fall apart
  • Fixed price only when you can write a one-page spec you will not change
  • If scope might move, T&M with a not-to-exceed cap (+5-12% over pure T&M) buys the same ceiling without the spiral

Anonymized project from our scoping files — part of the 600+ project quotes behind the engine.

Why the pricing model matters as much as the price

The same scope, built by the same vendor, can cost thousands more or less depending only on the contract model. Fixed price sells certainty, and vendors charge for it: expect to pay a premium built into the quote to cover their risk. Time and materials passes that risk back to you, which is only a good trade if your scope is not fully settled or you are optimizing for the lowest total cost rather than a hard ceiling. Neither model is universally safer - the fit depends on how locked your spec is, how much a ceiling matters to you, and how well you already know the vendor.

The middle option most buyers skip

A not-to-exceed cap on a time and materials contract gets skipped in most agency sales conversations because it is not the vendor’s default. It gives you the budget ceiling that makes fixed price attractive, without forcing you to lock a scope that is not ready to be locked. It is the right call any time your spec is mostly, but not fully, written down, or when you are working with a vendor you do not yet have a track record with. Once you have quotes back under whichever model you pick, run them through the Quote Analyzer or start from a data-backed budget with the RFP Generator.

Fixed price vs time and materials — FAQ

Should I choose hourly or fixed-price billing?

Fixed-price works best for well-defined projects under $10,000. Hourly is better for ongoing work or projects with evolving requirements. Always get a not-to-exceed cap with hourly billing.

What is a not-to-exceed cap on a time and materials contract?

A not-to-exceed cap is a maximum dollar ceiling written into a time and materials contract. You still pay for hours actually worked at the agreed rate, but the vendor cannot bill above the cap without a written change order. It gives you the ceiling protection of fixed price without locking in a scope that has not settled yet.

Why do fixed-price quotes cost more than time and materials?

Vendors price fixed-price work at 115-125% of their expected time and materials cost, because a fixed price makes them absorb the risk of the unknown. If the scope holds, you pay a premium for certainty. If the scope moves, you pay that premium plus change orders on top.

What actually happened in the Brooklyn law firm case file?

A $24,000 fixed-price website project grew by $9,500 in change orders, to $33,500, after the client added a custom intake form, multilingual support and a member portal three weeks in. The same vendor, the same scope, priced under time and materials instead, came out at $20,500 - $13,000 less. The pricing model made the difference, not the work.

Is time and materials safe with a vendor I have never worked with?

It is safer than fixed price with an unproven vendor and a scope that is not locked yet. Time and materials with a hard not-to-exceed cap gives you the same budget ceiling as fixed price, without betting a locked price on a spec that might move and a vendor whose change-order pricing you cannot yet judge.

What should go in the contract regardless of which model I pick?

Put the scope of work in writing, tie payment to milestones, get the change-order rate agreed before you sign, and if you are billing hourly, put a not-to-exceed cap in the contract. Once you have quotes under either model, the Quote Analyzer checks them against realistic market rates for $39.

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