How to Calculate PGU

When it comes to evaluating language, especially for students with suspected Developmental Language Disorder (DLD), standardized tests only tell part of the story. That’s why language sampling is such a powerful tool — and within that, one measure I return to again and again is percent grammatical utterances, or PGU.

In this post, I’ll walk you through what PGU is, why it’s helpful for school-age evaluations, and how to calculate it step-by-step using a narrative language sample.

Why PGU Matters for School-Age Students

Children with DLD can be really tricky to identify in the school setting. They can usually speak in full sentences, participate in group discussions, and appear to have typical language — especially on the surface. Their vocabulary often falls within the average range, which means they may score in the “low average” range on general language tests.

But here’s the thing: grammar and syntax are often the areas where these students struggle the most — and those difficulties show up big time when they hit upper elementary grades. Tasks like reading comprehension, writing, and solving word problems can become overwhelming.

That’s why it’s important to look beyond standard scores and gather objective data that reflects how a child is really communicating. PGU gives us that data.What Is PGU?

Percent Grammatical Utterances (PGU) is the percentage of a child’s utterances that are grammatically correct in a language sample.

It’s an easy calculation:

Grammatical utterances ÷ Total utterances (minus unintelligible ones) = PGU

This measure is appropriate for children aged 4 and up, and it’s especially useful in narrative samples. It helps us understand whether a child is producing language with appropriate morphology and syntax — and that information can support both diagnosis and goal-setting.

How to Calculate PGU (Step-by-Step in Word)

You don’t need any fancy software to calculate PGU. Here’s how I do it using a simple Word document:

1. Start with a Transcript

Use a transcript of the child’s narrative sample. (I like to save an original and work from a copy.)

2. Divide into Communication Units (C-units)

A C-unit includes an independent clause plus any dependent clauses. Break your transcript into these utterances.

3. Exclude Unintelligible Utterances

Any utterances that are too unclear to analyze shouldn’t be included in the total count.

4. Number the Utterances

Highlight all the utterances and use Word’s automatic numbering tool to count them. That gives you your denominator.

5. Identify the Grammatical Utterances

On the right side of the transcript, number only the utterances that are grammatically correct. That gives you your numerator.

6. Do the Math

Divide the grammatical utterances by the total number of utterances. Multiply by 100 to get a percentage.

Example:

• Total utterances: 65

• Grammatical utterances: 50

• PGU = 50 ÷ 65 = 0.77 → 77%

What the Research Says

PGU has strong research support, especially for identifying language impairment in school-age children.

A 2019 study by Dr. Ying Guo and colleagues established PGU cut-off scores for children ages 4 to 9. These cut-offs help determine whether a child’s PGU falls within the expected range — or if it suggests a likely language impairment.

For example, in the study:

• A 9-year-old with a PGU of 77% would fall below the cutoff.

• The measure showed 90% sensitivity, which is excellent for diagnostic accuracy.

That makes PGU both practical and reliable — perfect for school-based assessments.

Using PGU for Progress Monitoring

PGU isn’t just for evaluations. It’s also a great tool to:

• Track grammatical development over time

• Support your present levels and goal-writing

• Provide objective data in progress reports

You can repeat the process with updated narrative samples throughout the year to show clear, measurable changes in grammar skills.

Final Thoughts

PGU is one of the simplest — and most powerful — measures we can use as SLPs to assess language in a real-world, functional way. It gives us insight into the grammar and syntax skills that students need to succeed across academic areas.

Next time you’re reviewing a narrative sample, try calculating PGU. It just might give you the clarity you need to make a confident diagnostic decision.

Have you used PGU in your evaluations or progress monitoring?
Share your experiences in the comments or tag us on Instagram @hablacadabraslp — we’d love to hear how it’s working for you!