Free Sentence Diagram Generator
Turn any sentence into a clear Reed-Kellogg grammar diagram
Paste or type a sentence, and AI draws a clean, labeled Reed-Kellogg diagram breaking it into subject, predicate, objects, complements, and all modifiers — perfect for English class, grammar study, and language teaching.
Sentence diagram examples
Click any example to load its prompt, or use it as a starting point for your own grammar diagram.
What does this sentence diagram generator do?
It turns any English sentence into a clean Reed-Kellogg diagram — the classic visual grammar tool used in schools since the 19th century. You provide a sentence, and the AI identifies each word's grammatical role (subject, verb, direct object, indirect object, adjective, adverb, prepositional phrase, clause, etc.) and places them on the correct horizontal baselines, diagonal modifier lines, and connecting dotted lines. The result is a properly structured diagram you can use for homework, teaching, or grammar study without manually placing every line.
Why use a sentence diagram generator
- Diagramming sentences is a core grammar skill in elementary through high school English and linguistics courses.
- Drawing diagrams by hand is time-consuming and error-prone, especially for complex sentences with multiple clauses.
- A clear visual diagram shows grammatical relationships far more intuitively than written parsing alone.
- Teachers and tutors need quick, accurate diagrams to illustrate grammar rules on slides and handouts.
- Regenerating from text is much faster than re-drawing lines every time you revise the example sentence.
How to diagram a sentence
Type or paste your sentence into the box. For best results, include the complete sentence with all punctuation. If you want to focus on a specific grammatical feature — for example, indirect objects or participial phrases — mention it in your description. Generate the diagram, then verify that the main subject and verb sit on the primary horizontal baseline with a vertical dividing line, and that modifiers appear on diagonal lines below the word they modify. Refine your input and regenerate until every word is correctly placed.
Parts of a sentence diagram
- Baseline — the main horizontal line holding the subject, verb, and objects of the sentence.
- Subject | Predicate divider — a vertical line crossing the baseline to separate the complete subject from the complete predicate.
- Direct object bar — a short vertical line on the baseline between the verb and its direct object.
- Modifier lines — diagonal lines slanting down from the word being modified, carrying adjectives, adverbs, and articles.
- Prepositional phrase — a diagonal preposition line with a horizontal object line below, attached to the word it modifies.
- Subordinate clause connector — a dashed or dotted line linking a dependent clause to the word in the main clause it modifies.
Sentence Diagram Generator FAQ
What is a sentence diagram?
A sentence diagram is a visual representation of a sentence's grammatical structure. The most common style is the Reed-Kellogg diagram, which places subjects and predicates on a horizontal baseline and attaches modifiers on diagonal lines below the words they modify.
What is the Reed-Kellogg diagramming system?
The Reed-Kellogg system, developed in the 1870s by Alonzo Reed and Brainerd Kellogg, is the standard method taught in most American English grammar courses. It uses a horizontal baseline for core sentence elements and slanted lines for modifiers, making grammatical relationships visually clear at a glance.
How do I diagram a sentence with a prepositional phrase?
In a Reed-Kellogg diagram, a prepositional phrase hangs below the word it modifies. The preposition sits on a diagonal line and its object on a horizontal line below it. Describe the sentence and the AI will position the phrase correctly.
Can it diagram compound and complex sentences?
Yes. Compound sentences show two baselines connected by a dotted line with the conjunction on it. Complex sentences attach the subordinate clause to the main clause with a dashed line labeled with the subordinating conjunction. Just paste your full sentence.
Is it useful for English class or homework?
Absolutely. It produces clean, labeled diagrams suitable for grammar homework, language arts assignments, and teaching slides. Always review the generated diagram against your own grammatical analysis before submitting.
Is it free to use?
Each generation uses a small number of credits. New accounts receive free credits when they sign up, so you can diagram several sentences without a subscription.
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