Break up long sentences

What this check does

Counts sentences longer than 25 words and reports the share of total sentences they represent. The check fails when more than 25% of sentences on the page cross the 25-word threshold. This is independent of the average — Average sentence length measures the mean, this one measures the long tail.

Why it matters

Long sentences hide the main idea behind a chain of clauses. The reader has to hold every clause in working memory until the verb arrives — for a 35-word sentence, that’s an unconscious tax most readers pay by re-reading or skimming.

Research from the American Press Institute (replicated by Nielsen Norman, Hemingway, Yoast) finds:

• At 8 words per sentence, comprehension is around 100%.
• At 14 words, it drops to about 90%.
• At 25 words, it falls to around 60%.
• At 40 words, comprehension is around 20% — most readers stop trying.

The 25-word threshold isn’t arbitrary; it’s the inflection point.

How to fix it

Open the page in Hemingway or run a sentence-length highlighter, find each red sentence, and ask: “What are the two or three ideas in this sentence?” Then split.

Pattern: split at coordinating conjunctions (and, but, or)

Before (38 words):
We integrate with GA4 and Search Console so the audit can show real organic
traffic next to the rule failures, but only the Premium tier gets the integration
because it requires per-user OAuth tokens we have to encrypt at rest.

After (split into three):
We integrate with GA4 and Search Console. The audit shows real organic traffic
next to the rule failures. Only the Premium tier gets the integration — it
requires per-user OAuth tokens we encrypt at rest.

Pattern: hoist the subordinate clause to its own sentence

Before (31 words):
Because the migration ran without downtime during a low-traffic window on
Saturday night, none of the 17,000 imported users noticed when their accounts
moved from the legacy Postgres to the new cluster.

After:
The migration ran without downtime on Saturday night, during a low-traffic
window. None of the 17,000 imported users noticed when their accounts moved
to the new cluster.

Pattern: use a colon or em-dash to set off the punch line

Before: There is one thing we still haven't shipped before the email blast and
that is the migration email itself which has been waiting on Resend domain
verification.

After: One thing isn't shipped yet: the migration email — Resend's domain
verification is the holdup.

Pattern: bullet points are sentences too

A 60-word sentence with three “and” clauses is almost always three bullets:

Before: The Premium plan includes white-label PDFs, the integrations panel
linking GA4 and Search Console, branded subdomains for embedded reports, and
the brand-kit settings page where users upload logos and pick accent colors.

After:
The Premium plan includes:
- White-label PDFs.
- GA4 + Search Console integration.
- Branded subdomains for embedded reports.
- A brand-kit settings page (logo + accent color).

Tools.

• Hemingway Editor highlights sentences in red (over 25 words) and yellow (15–25 words). The goal isn’t zero red — it’s reducing the share until the page reads well.
• textstat (Python), readability (Node) — programmatic checks for CI.
• MS Word / Google Docs — built-in “Show readability statistics” and grammar suggestions flag long sentences.

Exceptions. Quoted material, code blocks, and long lists in serial commas count differently — MetricSpot strips code fences and quoted blocks before measuring. Technical specs and legal text can legitimately need long sentences; the 25% threshold gives you headroom.

Frequently asked questions

Does this apply to my landing-page hero or just blog body text?

It applies to all visible page text — heroes, body, footers. Hero copy is usually short by design, so the long-tail share is most affected by your body content.

What’s the difference between this and Average sentence length?

Average sentence length is the mean across all sentences (target: under 20). This rule looks at the share of very long sentences (target: under 25% are over 25 words). You can have a low average and still fail this one if a handful of monster sentences hide in the page.

My audience is engineers / scientists / lawyers — do I still need short sentences?

Even technical audiences read faster with shorter sentences — what changes is the vocabulary, not the structure. Engineers don’t enjoy parsing a 50-word sentence any more than the general public does; they just tolerate it more out of habit. See also Flesch–Kincaid grade level and Passive voice.