License: CC0 Public Domain

What is FAST?

FAST is a framework which is embedded in the Value Engineering methodology.

It is a graphical representation showing the functions of a project, product, process or service based on the questions “How” and “Why”.

There are two types of FAST diagrams, namely, the Technical FAST diagram and the Customer FAST diagram.

A technical FAST diagram focuses on the technical aspects of a specific portion of a total product. A customer FAST diagram focuses on the Customer and related to the product as a whole.
Charles Bytheway invented FAST in 1964.

He served as the director of Value Engineering in Salt Lake City until his retirement in 1981.

He is the first person to have been awarded the Miles Award by the Society of American Value Engineers, for his work in advancing Value Engineering.

It is said that “A problem well stated is a problem half solved”.

FAST helps in understanding the problems associated with a product or system.

What is a function?
We have to understand what is meant by the term function before we try to understand FAST.
What a product or service does is its function. It is the fundamental purpose of the product or service. In FAST diagrams a product/service is described in a two word format – an active word + a measurable noun.

The focus is on what tasks are to be performed and not how it is to be performed.

A practical example of the FAST approach:

#Activity – One expert prepares a document

#Function – This document improves quality

In the above example, though the activity is important, it does not directly benefit the customer.

It is the function which benefits the customer directly.

It is pleasantly surprising to realise that all of us are dealing with “functions” on a daily basis.
The following are examples of such functions.
Drink coffee

Drink milk

Eat eggs

Eat breakfast


Some technical examples of “functions” are

  • Generate Voltage
  • Transmit light
  • Carry load
  • Cool environment
  • Supply power
  • Blow air
  • Mount unit

An example from an automobile control system

Here” drive car “is a higher level function and the sub functions are as follows:-

  • Control speed
  • Control direction
  • Control visibility

FAST helps in productive thinking and can also be used as a problem solving tool for any issue.

It is not limited to products and services.

Interestingly, it can even be used to deal with personal issues like:

# How to raise good children

# How to lead a healthy life

The following is a basic FAST diagram


Benefits of FAST

  • Can be used as a problem solving tool
  • Teams can share the understanding of the project
  • Can organize and understand the relationships between functions.
  • Can be used as a communication tool
  • Can Stimulate creativity

Three key questions to be asked in a FAST Diagram:

  • How to achieve a function?
  • Why are we doing this function?
  • What other functions must we do along with this function?

Is there a “correct” FAST Diagram?

There is no such thing as a ‘correct’ FAST diagram.
There can be more than one FAST diagram to a product.

FAST is not an end product or result but a beginning to many improvements and solutions.

Having understood this versatile tool let us implement it fast


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