Choose hourly or fixed pricing by deciding who controls scope risk, measuring delivery variation and setting boundaries that protect contribution.
Short answer: Charge a fixed price when the output, inputs and revision boundary are clear and your last five comparable jobs vary by no more than 15% in delivery hours. Charge hourly when the customer controls the pace, discovery is necessary or scope can change materially. For uncertain work, use a paid diagnostic or hourly first stage with a cap, then fix the implementation price.
Hourly pricing transfers time risk to the customer but rewards slow delivery and leaves the total uncertain. Fixed pricing gives budget certainty but transfers scope and estimation risk to you.
Neither is inherently more professional. The right model puts risk with the party best able to control it and makes the completed purchase understandable before work begins.
Use the Scope-Risk Allocation Matrix
The Scope-Risk Allocation Matrix scores four conditions before you choose the billing unit.
- Output: Hourly is stronger: Investigation or advisory access; Fixed is stronger: Defined deliverable and acceptance test
- Inputs: Hourly is stronger: Customer supplies changing information; Fixed is stronger: Inputs are complete and standard
- Time variation: Hourly is stronger: Comparable jobs differ by more than 15%; Fixed is stronger: Last five jobs sit within a 15% band
- Control: Hourly is stronger: Customer directs priorities and revisions; Fixed is stronger: You control method and sequence
The 15% band is a working guide. A high-margin service can tolerate more variation, while a thin-margin job may need tighter estimates. Use your actual contribution and risk.
My position is that new providers should not promise fixed prices for work they have never timed. Sell a bounded hourly or diagnostic stage, learn the variation, then give the customer certainty where evidence supports it.
Use hourly pricing for genuine uncertainty
Hourly billing fits investigation, changing priorities, coaching, support and work where the customer can pause, redirect or add tasks. State the rate, billing increment, likely range, update frequency and any cap.
Do not use hourly billing to avoid scoping. The customer still needs to know what you will do first and how they can control spend. An estimate of 15 to 20 hours is more useful than “it takes as long as it takes”.
Track non-billable time. A £70 hourly rate is not £70 earned for every working hour. Selling, administration, gaps and rework can reduce realised revenue sharply. Divide total contribution by all constrained delivery hours when assessing viability.
Use a cap only when you are prepared to stop and ask for a new decision. A cap that you silently exceed is not a control.
Use fixed pricing for a controlled result
Fixed pricing works when the buyer can recognise completion and you can estimate delivery from comparable records. Define quantity, input format, revision, turnaround, meetings and customer responsibilities.
Build the price from expected hours, direct cost, overhead contribution and an uncertainty allowance. Do not merely multiply the optimistic estimate by an hourly rate. Use the median of comparable completed jobs and inspect the slowest case.
A fixed price rewards efficiency only when quality remains intact. Faster delivery caused by skipping checks is not margin improvement. Put an acceptance standard into the scope.
Change requests need a decision rule. Describe what counts as a change and whether it receives a fixed addition or hourly quote before beginning.
Put diagnosis before fixed implementation
Some work becomes predictable only after inspection. Price the diagnostic as a complete first purchase: findings, specification, priorities or implementation quote. The customer should receive value even if they stop.
After diagnosis, fix the price only for the known scope. Keep unresolved items as stated assumptions or separately priced options. This prevents you hiding uncertainty in a large defensive quote.
Safety, regulated advice and consumer contracts can require particular disclosures or standards. Requirements vary by country and sector, so obtain qualified local legal or professional advice for the actual engagement.
Worked example: Northmere Catalogue Editing
Northmere edits printed trade catalogues. A standard 80-page edit is expected to take 24 hours and carries £90 of direct checking and file-transfer cost. The owner’s required rate is £65 per delivery hour.
An hourly engagement at £65 would cost £1,560 if it takes 24 hours. Northmere considers a fixed fee of £1,650, which includes one consolidated revision round.
- 15 hours: Hourly customer price: £975; Fixed customer price: £1,650; Fixed contribution per hour after £90 cost: £104.00
- 24 hours: Hourly customer price: £1,560; Fixed customer price: £1,650; Fixed contribution per hour after £90 cost: £65.00
- 32 hours: Hourly customer price: £2,080; Fixed customer price: £1,650; Fixed contribution per hour after £90 cost: £48.75
At 24 hours, fixed contribution after direct cost is £1,650 minus £90 = £1,560, or £65 an hour. At 32 hours, it remains £1,560 but falls to £48.75 an hour. The customer gains price protection and Northmere carries the overrun.
The last five comparable catalogues took 22, 23, 24, 25 and 27 hours. The range around the 24-hour median is within about 12.5% at the upper end, so a fixed price is defensible. A new catalogue arriving in mixed file formats does not fit the evidence. Northmere prices a two-hour file assessment at £130 before offering a fixed edit.
The arithmetic shows why one billing rule cannot cover both conditions. Standard files belong in fixed pricing. Unknown files leave material scope risk and need diagnosis.
Compare expected contribution, not invoice size
For each model, calculate price less sale-driven cost, then divide by expected constrained hours. Run expected, low and high-hour cases. Check whether the weak case still covers your minimum requirement.
Hourly can produce a larger invoice when work expands, but collection risk and customer dissatisfaction may rise. Fixed can produce higher hourly contribution when you work efficiently, but one bad estimate can erase margin from several jobs.
Include sales effort. Fixed offers can be easier to approve and require fewer budget conversations. Hourly retainers may reduce proposal time. Measure the whole cycle rather than delivery alone.
Keep risk boundaries visible
For hourly work, send spend updates at an agreed point, such as every five hours, and obtain approval before crossing the estimate or cap. Record customer-directed changes.
For fixed work, use assumptions and exclusions that a capable buyer can understand. Do not bury the real boundary in small print while the proposal promises an unlimited result.
Avoid hybrid language that combines the worst of both: a “fixed estimate” that can rise whenever you choose. State whether the amount is a quote, estimate, cap or fixed fee. Legal meanings vary, so check local contract and consumer requirements.
Related guides
Choose the model over the next five jobs
Today, classify the work against the four matrix conditions. Review the hours and causes of variation across the last five comparable jobs. If no records exist, start hourly or with a paid diagnostic and a customer-approved cap.
For the next five jobs, record quoted scope, actual hours, changes, direct cost and contribution. Move to fixed pricing only when scope is controlled and the weak-hour case remains viable. Keep hourly pricing where the customer controls variation, and give them an update interval they can use to stop or redirect work.
Frequently asked questions
Do clients prefer fixed prices?
Many prefer knowing the total, but preference depends on trust and scope. A buyer may reject a large defensive fixed fee when a short investigation could establish what is needed. Others dislike hourly exposure they cannot control. Offer certainty at the level your evidence supports: a fixed diagnostic, a capped hourly stage or a fixed implementation. Do not ask preference in isolation. Explain the risk and boundaries of each option, then see which qualified buyers purchase and which model produces viable contribution.
How do I calculate a fixed fee from an hourly rate?
Use expected delivery hours from comparable completed work, multiply by the required contribution per hour, add direct cost and include a risk allowance for measured variation. Check the slow case as well as the average. If 24 hours at £65 plus £90 direct cost produces £1,650, a 32-hour case yields only £48.75 an hour before overhead. Decide whether that remains viable. Do not add a random percentage where the underlying scope is still unknown; diagnose the uncertainty first.
Should revisions be included in a fixed price?
Include a defined revision process when it is normal and estimable. State the number of rounds, who consolidates comments, what can change and the response deadline. A revision corrects or refines work within the agreed brief. A new audience, format or direction is a scope change. Price it separately. Unlimited revisions transfer customer indecision to your margin. Contract interpretation and consumer fairness rules vary, so make the boundary prominent and obtain qualified local advice where needed before quoting to customers.
Can I charge hourly for meetings and travel?
Yes, if you disclose the basis before the customer commits and it is lawful in your market. You can also build normal meetings and travel into a fixed price. Choose one clear treatment. Billing a low headline rate and revealing routine travel later damages trust. Record all time internally even when it is not separately billed, because it affects realised contribution. Tax and expense treatment varies by jurisdiction, so ask a qualified local accountant about your records rather than treating reimbursement as profit.
What if a fixed-price job takes less time than expected?
Keep the agreed price when you delivered the defined result and did not mislead the customer. They bought certainty and output, not a guaranteed number of hours. Check that speed came from skill or process rather than reduced quality. Record the actual time and use it in future estimates. You do not need to volunteer a refund because delivery was efficient, just as you cannot automatically charge more when your estimate was poor. An exception is a contract that explicitly reconciles actual cost.
What if an hourly client asks for a maximum budget?
Set a cap with a stop point. Explain what you expect to complete before the cap and what happens if uncertainty remains. Send updates at agreed intervals and pause before exceeding it. A cap converts some time risk back to you, so do not guarantee the full outcome when the budget may be insufficient. You can price a diagnostic within the cap, then give options. Confirm approvals in writing. The customer must be able to make a real decision before more cost accrues.
Can I use fixed prices for a monthly retainer?
Yes, when the monthly access, output, response standard and unused capacity are clear. A fixed retainer should not mean unlimited requests. Define included hours or deliverables, rollover, priority, meetings and excess work. Track actual use and contribution by customer for three months. If one account repeatedly consumes twice the assumed capacity, change scope or price at the next lawful review point. Notice and renewal rules vary by jurisdiction and contract, so obtain qualified local advice before changing any existing terms.
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