What is a Reed-Kellogg sentence diagram?

It's the sentence-diagramming system developed by Alonzo Reed and Brainerd Kellogg in their 1877 grammar textbook. The subject and verb sit on a horizontal baseline split by a vertical line; objects and predicate complements extend that line; modifiers hang below on slanted lines; and prepositional phrases hang from a diagonal-then-horizontal stand. It's still the diagram most American grammar and ESL courses mean when they say "diagram this sentence."

Does this tool parse my sentence automatically?

No. Automatic parsing of open-ended English into a correct diagram is not something a rule-based tool can do reliably — real sentences are too ambiguous. Instead, you identify the subject, verb, objects, and modifiers yourself in a short form, and the generator handles every line, angle, and divider so you don't have to draw by hand.

How do I diagram a sentence with a compound predicate?

Switch the predicate structure to "compound" and a second verb slot appears. Both verbs share the same subject and baseline, then split into two parallel lines joined by a dashed line carrying the conjunction (and, or, but). Each verb keeps its own object and modifier fields, so "The dog barked and chased the mail carrier" diagrams with two full verb lines under one subject.

Where do prepositional phrases go on a Reed-Kellogg diagram?

A prepositional phrase never sits on the main baseline. It hangs from whatever word it modifies — a diagonal line carries the preposition down, then a horizontal line carries its object, and any adjectives modifying that object hang below the horizontal line the same way ordinary modifiers do. In the generator, pick the word to attach a phrase to and this stand is built for you.

What's the difference between a direct object and a predicate noun on the diagram?

Both sit after the verb on the same baseline, but the divider tells them apart: a direct object follows a straight vertical line that stops at the baseline, while a predicate noun or predicate adjective follows a line that leans back toward the subject. That backward lean is the visual cue that the verb is a linking verb (is, seems, became) rather than an action verb.

Is a sentence diagram the same as a syntactic tree?

They describe the same sentence but answer different questions. A Reed-Kellogg diagram shows grammatical function — subject, object, modifier — laid out along a line, which is what most school grammar classes need. A syntactic tree shows how phrases nest inside each other, which is what a linguistics course studying constituent structure needs. If you want the tree notation instead, Figwise's syntactic tree generator covers that side.

Sentence Diagram Generator

Fill in the subject, verb, objects, and modifiers, and this sentence diagrammer draws the classic Reed-Kellogg lines for you — no grammar-parsing engine, no guessing where a phrase belongs.

Diagram Title

Predicate

Subject

Words modifying the subject

Verb 1

Verb type

Words modifying this verb

Direct objectIndirect object

Prepositional phrases

PrepositionObject of the preposition

Words modifying that object

Modifies

01HOW TO USE

How to Diagram a Sentence Here

This sentence diagram generator does not attempt to parse free-form English — you tell it what each word does, and it handles the geometry: the baseline, the dividers, and every slanted modifier line.

01
Enter the subject and verb
Type the simple subject and the main verb. They land on the horizontal baseline, split by the vertical line that marks the core subject-verb relationship.
02
Pick action or linking, then add objects
Choose whether the verb is an action verb or a linking verb. Action verbs unlock direct and indirect object fields; linking verbs unlock a predicate noun or predicate adjective slot instead.
03
Attach modifiers and prepositional phrases
Add adjectives, adverbs, and articles under any word, then add prepositional phrases and choose which word each one modifies. The tool places the slanted lines and phrase stands automatically.
04
Export the finished diagram
Download the sentence diagram as SVG for editing in a vector app, or as PNG for a worksheet, slide deck, or gradebook comment — both come straight out of your browser.

02EXAMPLES

What This Sentence Diagrammer Draws

Four sentence structures a grammar class actually meets, from a bare subject-verb pair to a compound predicate — each built with the same subject/verb/modifier fields.

A Simple Subject and Verb

"Birds sing." Just a subject and an intransitive verb on the baseline, split by one vertical divider — the smallest complete Reed-Kellogg diagram there is.

Adjectives and an Adverb as Modifiers

"The clever fox quickly jumped." Two adjectives hang below the subject on slanted lines, and an adverb hangs below the verb the same way — the standard way Reed-Kellogg diagrams show modification.

A Prepositional Phrase

"The fox jumped over the lazy dog." The phrase hangs from the verb on its own diagonal-then-horizontal stand, with the preposition on the slant and its object, plus modifiers, on the ledge.

A Compound Predicate

"The dog barked and chased the mail carrier." One subject splits into two parallel verb lines joined by a dashed conjunction line — this is where diagramming sentences starts to show real sentence structure.

03COMPARE

Reed-Kellogg Diagram vs. Syntactic Tree

Both notations describe how a sentence is built, but they answer different classroom questions — pick the one that matches what you're teaching, or use both side by side.

syntactic tree generator

Reed-Kellogg Sentence Diagram

Function on a line

Shows what role each word plays: subject, verb, object, modifier — the grammar-class question of "what is this word doing here?"
Keeps word order visible along the baseline, which is why English and ESL grammar courses still lean on it for parts of speech and sentence patterns.
Reads naturally left to right, so it works well on a worksheet or on a whiteboard mid-lesson.
Struggles with deeply nested clauses — it was built for the sentence patterns of a traditional grammar curriculum, not for recursive structure.

Syntactic Tree

Constituent structure

Shows how phrases nest inside larger phrases — the linguistics-class question of "what groups with what?"
Handles recursive and embedded clauses cleanly, which is why syntax courses and formal grammar analysis reach for tree notation.
Abstracts away from linear word order in favor of hierarchical branching, closer to how a parser represents a sentence.
Takes more practice to read at a glance for students who just need to know what a direct object is.

04FEATURES

What the Sentence Diagram Generator Handles For You

Close-up of a Reed-Kellogg baseline with subject-verb divider and object divider rendered precisely

Direct Reed-Kellogg Geometry, Not a Drawing Tool

There's no canvas to drag lines on. Fill in subject, verb, and object fields and the sentence diagram generator places the baseline, the crossing divider between subject and verb, and the non-crossing divider before a direct object exactly where Reed-Kellogg convention puts them.

Side-by-side comparison of an action-verb diagram and a linking-verb diagram with different divider lines

Action and Linking Verbs Get Different Layouts

Switch a verb between action and linking and the diagram itself changes: action verbs add a direct object after a straight vertical divider that stops at the baseline, plus an indirect object slanting down from the verb onto a short horizontal line beneath it; linking verbs swap in the backward-leaning line that carries a predicate noun or predicate adjective back toward the subject.

Sentence diagram with several modifier lines and a prepositional phrase attached under different words

Modifiers and Phrases Attach to the Right Word

Every adjective, adverb, and prepositional phrase you add asks which word it modifies, then lands on its own slanted line under that word — including phrases nested under the direct object or the indirect object, not just the main verb.

05FAQ