Linsear Write: the readability formula that counts easy and hard words by hand

Most readability formulas were designed to be computed by a machine. Linsear Write was designed to be computed by a person with a pencil, a 100-word sample, and a few minutes. That constraint shaped everything about it — and it's exactly why the formula still teaches you something the slicker formulas hide. If you've ever wanted to feel what makes a passage hard rather than just read a number off a screen, Linsear Write is the one to understand.

This piece walks through where it came from, how the calculation actually works step by step, what its odd two-branch final formula is doing, and when it earns a place next to better-known measures like Flesch–Kincaid.

Where Linsear Write came from

Like the Automated Readability Index, Linsear Write traces back to the US Air Force, which in the 1970s needed a way to check whether technical manuals were pitched at the right reading level for enlisted personnel. The catch was that the people doing the checking weren't computers — they were technical writers and trainers grading documents by hand. So the formula had to be something a human could run reliably in the field: take a sample, sort words into two bins, do a little arithmetic, read off a grade. No pronunciation dictionary, no long-division-heavy weights, no software.

That heritage explains its quirks. Where Flesch averages syllables across every word, Linsear Write makes a single, blunt distinction that a tired human can apply consistently: is this word easy or hard?

How the calculation works

Linsear Write operates on a 100-word sample — the first 100 words of your text, taken in whole sentences. Our Linsear Write calculator walks through your sentences accumulating words until it reaches 100, counting how many complete sentences that took. Then it sorts every word in the sample into one of two buckets:

• Easy words — two syllables or fewer. Each counts as 1 point.
• Hard words — three syllables or more. Each counts as 3 points.

So a hard word is worth three easy ones. That weighting is the heart of the formula: it says polysyllabic vocabulary is the dominant driver of difficulty, and it makes that bias explicit and countable rather than burying it in a regression coefficient.

Add up the points and divide by the number of sentences in the sample to get a provisional number:

raw = (easy words × 1 + hard words × 3) / sentences

Dividing by sentence count folds in sentence length automatically: pack the same 100 words into fewer sentences and each sentence carries more weight, pushing the raw score up. Long sentences and hard words both raise the grade, which matches intuition.

The two-branch final step

The raw number isn't the grade. Linsear Write finishes with a small conditional that trips up people seeing it for the first time:

if raw > 20:  grade = raw / 2
else:          grade = (raw − 2) / 2

Why two branches? The subtraction of 2 in the lower branch is a calibration nudge that keeps easy text from scoring too high, while text dense enough to push the raw value above 20 skips that correction. In practice the seam sits well above ordinary prose, so most everyday writing takes the (raw − 2) / 2 path. The output is a US grade level: 8 means roughly eighth-grade reading, 12 is late high school, and the general-audience comfort zone is around grades 6–9.

Why the easy/hard split is the interesting part

Formulas like Flesch–Kincaid average syllables across every word, which smooths everything into a single ratio. Linsear Write refuses to smooth. By bucketing words and tripling the cost of the hard ones, it draws a bright line you can see while you edit: replace one three-syllable word with a one- or two-syllable synonym and you've literally removed three points from the tally. The formula rewards the exact edit a plain-language reviewer would ask for, and it shows its work in a way an averaged ratio never does.

This makes Linsear Write unusually good as a teaching tool. Hand a writer the easy/hard breakdown and they immediately grasp that "utilize", "facilitate", and "implementation" are what's dragging their grade up — far more actionable than "your Flesch–Kincaid is 11.2".

Where Linsear Write goes wrong

The same design choices that make it teachable also limit it:

• The 100-word sample is small. A single sample swings hard on one unusual sentence. For a stable reading, score several samples from different sections and compare, rather than trusting one paragraph.
• The two-syllable cutoff is arbitrary. "Water" and "into" are two-syllable easy words; "eke" and "wry" are one-syllable but genuinely hard. Like every syllable-based measure, Linsear Write equates short with simple, which isn't always true — for vocabulary-aware scoring, Dale–Chall checks words against a familiarity list instead.
• It depends on syllable counting. Any tool that splits words by syllable is estimating pronunciation, and proper nouns or invented words can be miscounted. The character-based Coleman–Liau Index sidesteps that entirely.
• It's English-only. The syllable rules and the easy/hard threshold were calibrated on English and don't transfer to other languages.

Putting it to use

Reach for Linsear Write when you want a readability check that doubles as an editing guide — technical documentation, training material, instructions, or anything where the goal is to hunt down and replace heavy vocabulary. Paste a representative passage into the Linsear Write calculator, read the grade it returns, and aim for the 6–9 band for a general audience. Because no single formula is the last word, sanity-check it against its relatives: Flesch–Kincaid as the standard syllable-based grade, or a readability consensus that averages several formulas at once so one measure's quirk doesn't steer you wrong.