FORCAST is designed for technical text such as forms and instructions. It uses single‑syllable word counts.
Built and maintained by Paul Clark, Redmoon Software · Last verified · Sources
Use FORCAST for technical, non-narrative text: forms, instructions, parts manuals, safety-data sheets. It is the only mainstream formula that does not require sentence boundaries, so it works on bullet-heavy or fragmented documents that defeat other formulas.
FORCAST is unique among readability formulas in ignoring sentences. For technical documentation it is more reliable than Flesch–Kincaid; for prose, much less so.
FORCAST was developed in 1973 by Caylor, Sticht, Fox, and Ford specifically for technical, non-narrative writing (forms, manuals, instructions).
It uses a 150-word sample and counts single-syllable words: 20 − (single-syllable words / 10).
It does not require sentence-level analysis, which makes it ideal for evaluating bulleted or fragmented text.
FORCAST is designed for non-narrative text: instructions, forms, technical manuals. It does not require sentence-level analysis.
It samples a 150-word passage and counts how many of those words have exactly one syllable. The fewer single-syllable words in the sample, the higher the resulting grade level.
It was designed for technical material like forms, manuals, and instructions, which often lack normal sentences. Because it only counts single-syllable words, it works on text where sentence-based formulas would fail.
In practice it typically returns grades between about 5 and 12, since the score is 20 minus one-tenth of the single-syllable word count in 150 words. It was originally validated for the grade 5 to 12 range used by military technical manuals.
Input
150-word technical-procedure sample with ~85 single-syllable words.
Output
FORCAST grade level: 11.5 — 11th–12th grade.
FORCAST = 20 − (single-syllable words in 150-word sample / 10). 85 single-syllable words → 20 − 8.5 = 11.5.
FORCAST is unique in this collection: it uses no sentence-length term at all. The grade level comes only from the count of single-syllable words in a 150-word sample.
That is not an oversight. FORCAST was developed for US Army technical material in the 1970s, and the target documents were forms, checklists, manuals and equipment lists — text where "sentences" either do not exist or are so irregular that measuring their length produces noise rather than signal.
Use FORCAST on anything that is not continuous prose: application forms, instructions, bulleted procedures, tables of steps, UI copy. Every other formula here will either mis-punctuate that material into absurd "sentences" or refuse to produce a sensible number.
Do not use it on ordinary prose. With no sentence term, it is blind to exactly the failure that most damages readability in continuous writing — the sentence that runs on for sixty words. A document can be genuinely unreadable and score well on FORCAST.
The method behind this tool, so you can check it rather than take it on trust.
Sticht, T.G. (ed.) (1975). Reading for Working: A Functional Literacy Anthology. Human Resources Research Organization.
FORCAST was developed for US Army technical material and, unusually, does not use sentence length — which is why it suits forms and lists.
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