BYTETOOLS

FORCAST Readability Calculator

Calculate the FORCAST readability grade for forms, checklists and technical manuals. It ignores sentence length entirely and counts single-syllable words.

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FORCAST grade
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Single-syllable words / 150
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Blocks measured
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Words in text

Paste some text to see the FORCAST grade level.

Syllables are counted with a written-English heuristic (vowel groups plus silent-“e” and suffix rules), not a pronunciation dictionary, so an unusual word or a name can be classified wrongly. Over 150 words the errors mostly cancel out.

What is the FORCAST Readability Calculator?

FORCAST is the readability formula built for text that is not written in sentences. Forms, checklists, job aids, parts catalogues and training material are full of fragments, headings and list items, which makes every sentence-based formula — Flesch, Fog, SMOG — produce nonsense.

  • Exact FORCAST formula: 20 minus single-syllable words per 150, divided by 10
  • Score the first 150 words or average every block in a long document
  • The 150-word sample shown with every single-syllable word highlighted
  • Per-block table so you can see which sections are hardest
  • No sentence detection at all — works on fragments and list items
  • Fully offline, in-browser processing with nothing uploaded

How to use the FORCAST Readability Calculator

  1. 1

    Paste your form, checklist, manual or training text into the input box.

  2. 2

    Choose the first 150 words for the classic procedure, or average every 150-word block.

  3. 3

    Read the FORCAST grade and the number of single-syllable words behind it.

  4. 4

    Check the highlighted sample to see which words the formula treated as simple.

  5. 5

    Simplify the multi-syllable vocabulary and watch the grade fall as you edit.

About the FORCAST Readability Calculator

FORCAST is the readability formula built for text that is not written in sentences. Forms, checklists, job aids, parts catalogues and training material are full of fragments, headings and list items, which makes every sentence-based formula — Flesch, Fog, SMOG — produce nonsense. FORCAST solves that by ignoring sentences completely and looking only at vocabulary.

The formula is one line: take a 150-word sample, count the words of a single syllable, divide by 10 and subtract from 20. The result is a US grade level. This calculator does that on the first 150 words or averages every 150-word block in a longer document, and shows you the exact sample it used with each single-syllable word highlighted.

All the counting runs in your browser with JavaScript. Nothing is uploaded, so internal procedures, safety instructions and unpublished training material are safe to paste, and the calculator keeps working offline.

Frequently asked questions

What is the FORCAST readability formula?

FORCAST estimates a US reading grade level from vocabulary alone. Take a 150-word sample, count how many words have a single syllable, divide that count by 10 and subtract the result from 20. A sample with 120 single-syllable words scores grade 8.

When should I use FORCAST instead of Flesch or Fog?

Use it whenever the text is not continuous prose. Forms, checklists, menus, catalogues and job aids have no real sentences, so sentence-length formulas give wildly wrong answers. FORCAST was developed by the US military for exactly this material.

What is a good FORCAST score?

It is a grade level, so lower is easier. Public-facing forms and safety instructions usually aim for grade 8 or below, while technical manuals for trained staff commonly sit between 10 and 12. Anything above 13 will slow down most readers.

Why does FORCAST ignore sentence length?

Because in the documents it was designed for, sentence length is meaningless — a checklist item is not a sentence. Removing that term makes the formula stable on text where a sentence-based score would swing wildly depending on how the punctuation happened to fall.

How is the syllable count worked out?

With a written-English heuristic that counts vowel groups and adjusts for silent “e” and common suffixes, not a pronunciation dictionary. It is right for the great majority of everyday words, and over a 150-word sample the occasional error has almost no effect on the score.

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