Readability Score

Overview

Readability Score first replaces every tab, carriage return and line feed in `text` with a space and trims it; empty text returns a 400 error. Because line breaks become spaces, a heading or bullet without terminal punctuation runs into the next sentence, which raises the sentence-length based scores. Add periods to list items if you want them counted as separate sentences.

`textCounts.syllableCount`, `lexiconCount` (words) and `sentenceCount` come from the text-readability library, as do Flesch Reading Ease, Flesch-Kincaid Grade, Gunning Fog, Coleman-Liau, the Automated Readability Index and the New Dale-Chall score. `smogIndex` is taken from the readability-scores library instead. These are standard formulas over syllables per word, words per sentence, characters per word, polysyllabic word counts and, for Dale-Chall, the share of words outside a list of familiar words.

All grade-style metrics and the Dale-Chall score are floored at 1. `fleschReadingEase` is not floored: it runs roughly 0 to 100 with higher meaning easier, and very dense text can go below 0. Its label in `readabilityText` uses lower bounds of 90 very easy, 80 easy, 70 fairly easy, 60 standard, 50 fairly difficult, 30 difficult, and very confusing below that. The Dale-Chall label maps whole-number bands from "average 4th-grade student or lower" up to "13th to 15th-grade (college) student" for 9 and above.

`averageGradeLevel` is the mean of Flesch-Kincaid, Gunning Fog, Coleman-Liau, SMOG and ARI, rounded to one decimal. `targetAudience` reads from it: 16 and above post-graduate, 13 college, 9 high school, 6 middle school, otherwise elementary. Short samples of a sentence or two produce unstable scores. Results are identical on every plan.

Live Test Readability Score Source →

Formula

One function covers the whole catalog: the first argument names the source, the next are its inputs, and the field after them says which single value lands in the cell. Formulas covers the grammar that applies to all of them.

=VERVE("readabilityscore", A2, "averageGradeLevel")

A2 holds the text you are looking up. Drag the formula down and each row resolves on its own.

With literal values

Nothing has to come from a cell — typed values work the same way.

=VERVE("readabilityscore", "The quick brown fox jumps over the lazy dog. This sentence contains every letter of the alphabet.", "averageGradeLevel")

Inputs

Required inputs are positional, in the order below, followed by the field. Everything else is passed as a "name", value pair after that — the same shape as SUMIFS. Premium inputs are accepted on every plan but only take effect on plans that include them.

Input	Type	Where it goes	Description
`text`Required	string	argument 2 (A2)	The text to calculate the readability score of

What lands in your sheet

The field — the argument after the inputs — is what makes the formula resolve to one cell. Its value is a dot-path from the table below, so swapping it is how you pull a different value — one formula per column.

Seeing everything at once

Leave the field out and the formula returns the whole response instead: two columns, field name on the left and value on the right, spilling from the cell you typed in.

=VERVE("readabilityscore", A2)

Good for exploring, not for filling down

The second row's table would land on top of the first's, and every cell after the first reads #REF! (#SPILL! in Excel). Keep one per sheet, or name a field, and leave the cells below and to the right empty.

Response fields

Paths are relative to data. Each one is exactly what the field argument accepts, so swapping it is how you pull a different value into a cell. On a plan without a Premium field the cell reads #PREMIUM(field) rather than a value, so a locked field never looks like a real answer.

Use as the field	Type	Example cell value	Description
`textCounts`	object	`{…}`	Counts of syllables, words, and sentences found in the analyzed text
`textCounts.syllableCount`	number	`82`	Total number of syllables detected in the text
`textCounts.lexiconCount`	number	`49`	Total number of words in the text
`textCounts.sentenceCount`	number	`1`	Total number of sentences detected in the text
`readability`	object	`{…}`	Raw numeric scores from each readability formula
`readability.fleschReadingEase`	number	`13.28`	Flesch Reading Ease score on a 0-100 scale; higher scores mean the text is easier to read
`readability.fleschKincaidGrade`	number	`23.6`	Flesch-Kincaid Grade Level; the approximate U.S. school grade a reader needs to understand the text
`readability.gunningFog`	number	`26.95`	Gunning Fog index; the estimated years of formal education a reader needs to understand the text on a first reading
`readability.colemanLiauIndex`	number	`13.19`	Coleman-Liau Index; an estimated U.S. grade level based on characters per word and words per sentence
`readability.smogIndex`	number	`22.08`	SMOG Index; the estimated years of education needed to understand the text, based on its count of polysyllabic words
`readability.automatedReadabilityIndex`	number	`27.8`	Automated Readability Index; an estimated U.S. grade level based on characters per word and words per sentence
`readability.daleChallReadabilityScore`	number	`17`	New Dale-Chall score; a readability rating based on how many words in the text are outside a list of words familiar to average 4th-grade readers
`readabilityText`	object	`{…}`	Plain-language interpretations of the numeric readability scores
`readabilityText.fleschReadingEase`	string	`very confusing`	Plain-language difficulty label derived from the Flesch Reading Ease score, e.g. "very easy" or "very confusing"
`readabilityText.daleChallReadabilityScore`	string	`average 13th to 15th-grade (college) student`	Plain-language grade-level description derived from the Dale-Chall score, e.g. "average 4th-grade student or lower"
`averageGradeLevel`	number	`22.7`	Average grade level computed by averaging the grade-based metrics (Flesch-Kincaid, Gunning Fog, Coleman-Liau, SMOG, and Automated Readability Index)
`targetAudience`	string	`post-graduate`	Suggested target audience derived from the average grade level, e.g. "elementary", "high school", or "post-graduate"

Filling a whole column

Both platforms make one batched call for a column rather than one request per cell, and both cost the same — 2 credits per row looked up. How you write it differs, because the two runtimes batch at different points.

Rows 2–100 in one call

=VERVE("readabilityscore", A2:A100, "averageGradeLevel")

In Google Sheets, give the arguments ranges and the answers spill down from the cell you typed in. Custom functions there run synchronously and in isolation, so dragged cells cannot be coalesced — the range form is how a column becomes one call. The field is required here: a per-row two-column table has nowhere to spill. Use a full column per input (A2:A100, not A2) — a single-cell reference is read as row 1 only and the rest of the column comes back blank.

In Excel, type the formula once and fill down — no range form and none needed, because its runtime is asynchronous and the add-in coalesces the calls a fill produces into a single batched request. Do not hand VERVE.CALL a range: Excel flattens it into positional arguments, so A2:A100 arrives as a hundred separate arguments and the cell reads #ERR rather than filling.

Either way, column A holds your text values and the answers land beside them, one row each, blank rows skipped.

When a cell doesn't fill

A failed lookup returns readable text starting with #ERR rather than a spreadsheet error, because Excel cannot show a custom message on a real error — you would get a bare #VALUE! with no reason. The trade-off is that IFERROR() will not catch it; test with LEFT(cell, 4) = "#ERR" instead. Error handling covers the rest.

Cell reads	What happened
`#ERR Not connected`	No API key saved. Open the side panel and connect your account.
`#ERR Replace <name> with a cell or value`	A preview formula was copied as-is. Swap the placeholder for a cell reference.
`#ERR No "x" in readabilityscore`	An option name this source does not take. The message lists the ones it does.
`#ERR No data point "…"`	The field path is not in the response. Check it against the table above.
`#PREMIUM(field)`	The field exists but your plan does not include it.
`#ERR Out of credits`	The cycle's credits are spent. Usage resets on your billing date.

Before the formula works

The add-in reads the API key you saved once in the side panel — the key never goes in the formula, so a shared sheet does not leak it and a collaborator without access simply sees the last calculated values.

Install the add-in for Google Sheets or Excel.
Open the side panel and sign in, or paste a key from your dashboard.
Type the formula above into any cell.

Use cases

Editorial CMS Publishing: Before publishing articles, newsroom CMS editors check the Flesch-Kincaid grade level and word counts to match target reader expectations.
Patient Instructions Review: When clinicians draft care summaries, health portals flag passages scoring above an elementary target audience so staff can rephrase dense medical terms.
Curriculum Reading Assessment: To assign books to suitable grade bands, edtech apps evaluate uploaded chapters against Dale-Chall scores and the average grade level.
Consumer Contract Auditing: Flag convoluted policy clauses during drafting by checking consumer agreements against the Gunning Fog index and reading ease ratings.