Fixed price versus hourly billing: compare risk and revenue

Fixed-price work ties the customer’s charge to an agreed deliverable. Hourly billing ties it to agreed billable time. Neither automatically produces a better margin; the result depends on the scope, rate, actual hours and collection.

Compare identical work

Suppose a project is estimated at 20 hours. Labour costs 40 per hour and other included costs are 200. A fixed quote is 1,500; an hourly proposal is 75 per hour with the 200 cost absorbed by the provider. The same included cost base is used in both cases.

Actual hours	Included cost	Fixed revenue	Fixed retained amount	Hourly revenue	Hourly retained amount
16	840	1,500	660	1,200	360
20	1,000	1,500	500	1,500	500
28	1,320	1,500	180	2,100	780

Hourly revenue assumes every listed hour is billable, accepted and paid. A cap, disputed time or unpaid rework breaks that assumption. Fixed revenue assumes unchanged scope and no separately approved change.

Identify which uncertainty you can manage

A defined output with repeatable delivery records makes fixed-price estimation easier. Uncertain discovery work can be separated into a bounded phase before a delivery quote. Hourly billing still needs time records, an agreed rate, scope and a way to notify the customer before expected hours are exceeded.

At 28 hours, the fixed quote retains 12% of revenue on the included costs. The hourly case retains about 37.14%, but the customer pays 600 more than the original expectation. A margin calculation cannot tell you whether that increase will be accepted.

Choose the agreement, then test its economics

Write down what is included, the treatment of revisions, any cap and the approval process for changes. Do not switch billing assumptions midway through the model. Follow scope change pricing for separately requested work and review estimated versus actual cost after completion.

Method and scope

All amounts above are hypothetical teaching figures in one currency, excluding tax unless stated otherwise. These are original scenarios, not market prices, benchmark targets or professional recommendations. The references support the underlying concepts, not the example assumptions. This AI-assisted explanation has not had independent professional review. Calculation methods and limitations.