This is one of the questions clients ask most often. Sometimes other parts of the business are already planned, sometimes an existing website needs to be rebuilt, and sometimes the question is simply about setting expectations.
Those expectations are often influenced by advertisements promising a website in a single day.
Although a very simple page can technically be produced that quickly, it is usually not a sensible target when the website plays an important role in the business.
Projects rushed into one day or even one week can easily accumulate bugs, generic design decisions, incomplete content and functional problems if the scope is larger than a basic landing page.

The most useful answer therefore begins with another question:
What kind of website do you need?
Development time depends on the type and quality of design, the number of functions and pages, the amount of content, and any external systems that must be integrated.
Requirements such as API integrations, warehouse or inventory synchronization, payment systems, customer accounts and e-commerce functionality can extend a project substantially.
The more functionality a site requires—and the more refined its design, animations and interactions need to be—the more time developers and designers need for implementation, testing and revision.

Communication
If the client does not yet know what a basic website should contain or cannot clearly explain expectations, discovery and revision usually take longer.
The situation becomes more difficult when communication slows during the project, questions remain unanswered or decisions are repeatedly changed after implementation.
In those cases, sections of the website may need to be rewritten or redesigned. A fundamental redesign late in the project can be similar to starting a new phase from the beginning.
Developers also encounter technical problems, so a realistic schedule should include time for testing and unexpected issues rather than treating every day as pure feature development.
How can you speed up website development?
Before development begins, review websites and pages you like and identify specific design or functional elements that are relevant to your project.

This gives the development team clearer references and reduces time spent interpreting vague expectations.
Fast, detailed feedback is equally important. If you dislike a component, identifying the problem early makes it easier to change before other work depends on it.
When you can also explain what you would prefer instead, the team can respond more quickly and may be able to suggest alternatives that solve the same problem more effectively.