Other readability formulas work great when you’re writing a narrative. What about when you’re not, and how can the FORCAST formula help you analyze incomplete sentences?

What is the FORCAST formula?

The FORCAST formula is a calculation designed to analyze technical documents, training manuals, forms and surveys.

The mathematical formula is:

Grade level = 20 − (N / 10)
Where N = number of single-syllable words in a 150-word sample.

It’s a unique readability formula. Unlike most other readability formulas, it doesn’t rely on complete sentences for its analysis.

It does this by only using a vocabulary element.

It’s recommended for technical training material and surveys, questionnaires or multiple question tests.

Unlike the many other algorithms we offer, it was not designed for school material. This is because it can’t calculate below a fifth-grade level of comprehension.

Where did the FORCAST formula come from?

In the 70s, new readability formulas became as popular as flares, platforms and Fleetwood Mac.

FORCAST was one of the outcomes of this trend. It was the result of a study carried out by The Human Resources Research Organisation of Alexandria, Virginia - HumRRO - in 1973.

HumRRO was originally founded to conduct research and develop tools for the US army.

They wanted to find a unique readability solution. One which would allow the army to improve their training documents for new and less skilled personnel.

FORCAST was a great solution for functional literacy in non-narrative materials.

Non-narrative includes surveys, questionnaires and multiple-choice tests.

Researcher Thomas Sticht received Unesco's Mahatma Gandhi Medal after his contribution to the research.

He was passionate about functional context theory. His research helped adult learners accomplish difficult tasks more quickly.

Pilot at work | free readability test

When is FORCAST most useful?

FORCAST is a formula focused on functional literacy. Unesco defines functional literacy as:

‘The ability to identify, understand, interpret, create, communicate and compute, using printed and written materials associated with varying contexts’.

The aim of functional literacy is to set up individuals for a lifetime of learning. By encouraging simplification, FORCAST empowered trainees to reach their goals.

This highlights the importance of the core principle of readability. Although improving readability helps to craft a text which is easily digestible, readability isn’t just about this.

In a training context, it’s also about empowering the trainee to overcome challenges. This is much easier without unnecessary road-blocks such as convoluted language.

Readability also ultimately saves time and money for the company producing the material.

Because it’s easy to use and helped them to write publications which were easier to understand, the US Air Force officially approved FORCAST as a tool in the late 70s.

If it’s good enough for the US Air Force, it’s certainly an asset to any technical writer. It’s also an invaluable tool for any individual or company writing a questionnaire.

Let’s say you’re creating a survey for your customers to see if you can glean some insight on why they do business with you.

You want to use the survey to discover pain points. You also want to know what customers love about your product or service.

What use is your survey if some of your questions have ambiguities due to their lack of clarity? If your survey isn’t readable, the results of your survey aren’t reliable.

The validity depends on how well your reader can relate to and understand your questions and statements.

Think of it as a comprehension test - your reader is given a passage of text, then asked to respond to it.

By using the FORCAST formula, you can make sure you’re writing in plain, functional language. This will help your reader to understand your text more quickly so they can give you a fully informed response.

When writing multiple choice questions, you can rely on FORCAST to still analyze any incomplete or fragmented sentences accurately.

You don’t need to write narratively or in complete sentences for this formula to calculate correctly.

How can I get my FORCAST grade?

Similarly to many readability formulas, the FORCAST readability formula is interpreted as a US education grade.

You can view it in the list of readability grade levels on the right-hand side of the ReadablePro tool.

Forcast readabilty grade | free readability test

You can use any of the following methods to discover your FORCAST grade:

  • Go to readable tools → score text and type or paste text into the text box
  • Go to readable tools → score text files - word, pdf - and upload a file for scoring
  • Score an URL by going to readable tools → score an URL or bulk score URLs
  • Audit your website for readability by clicking on select or add a new website. This indexes every page on your site

Because it doesn’t measure sentence length, don’t be surprised if the FORCAST formula differs a little from other formulas. This is particularly apparent if you have a lot of tables and lists in your text.

The FORCAST result is interpreted to a grade in line with the US education system. But, FORCAST may run higher than a formula such as Flesch Kincaid if you’re not writing for the general public.  

If you’re a technical writer, keep in mind that a higher portion of your writing will be necessary terminology than general writing.

So don’t be discouraged - many readability formulas are designed for uses including education. Their grades have wider parameters.

We recommend aiming for a FORCAST grade of 9-10.

If you’re writing a document where tables and lists are a concern, FORCAST could be the formula for you. Give it a try today and see if your material keeps your audience in mind.

Laura Kelly

Laura is a content writer and customer success champion at Readable. She's a Literature MA graduate who loves poetry, a good coffee and 35mm photography.