Simple Sentence Diagrammer

The Reed-Kellogg system is a visual method for displaying the grammatical structure of sentences, developed by Alonzo Reed and Brainerd Kellogg in the late 19th century. It uses a horizontal baseline with vertical and slanted lines to represent how words relate to each other syntactically. The subject and predicate rest on the main horizontal line, separated by a vertical line. Modifiers branch off via slanted lines beneath the words they modify. This system was widely taught in American schools through the 1960s and remains a powerful tool for understanding English grammar.

Type any English sentence into the input field and click "Diagram It". Our tool uses a rule-based parser to identify the main sentence components: subject, verb, object, adjectives, adverbs, and prepositional phrases. It then renders a Reed-Kellogg style diagram on the canvas. You can also click any preset example to see pre-analyzed sentences. For best results with custom sentences, use clear, straightforward structures. The tool handles simple, compound, and moderately complex sentences. Download your diagram as a PNG image anytime.

This tool works best with declarative English sentences that follow standard Subject-Verb-Object (SVO) word order. Simple sentences like "The dog chased the cat," sentences with adjectives and adverbs like "The little boy ran quickly," and sentences with prepositional phrases like "The birds flew over the lake" all produce excellent diagrams. Very complex sentences with multiple clauses, passive voice constructions, or heavy nesting may yield simplified diagrams. We recommend starting with our preset examples to understand the tool's capabilities.

Colors help distinguish grammatical roles at a glance: Blue indicates the subject (who or what the sentence is about), Red marks the verb/predicate (the action or state), Green highlights the direct object (what receives the action), Orange/Amber shows modifiers like adjectives and adverbs, and Purple identifies prepositions within prepositional phrases. The legend above the diagram canvas provides a quick reference.

Yes! Simply type your sentence into the input field and click "Diagram It" or press Enter. The built-in parser will analyze your sentence and generate a diagram. While our preset examples guarantee perfect results, custom sentences may vary in accuracy depending on structural complexity. For the most accurate diagrams, try using straightforward word order and avoid overly nested clauses. If the parser struggles, you'll see a helpful banner with suggestions. We're continuously improving the parsing engine.

While less common in mainstream public education since the 1970s, sentence diagramming has experienced a resurgence in classical education, homeschool curricula, Montessori programs, and among grammar enthusiasts. Many educators believe diagramming builds a deeper, more intuitive understanding of syntax than traditional grammar worksheets. It's also popular among ESL/EFL teachers as a visual aid. The Reed-Kellogg method specifically develops analytical thinking about language structure, making it valuable for students of all ages.

Teachers can use this diagrammer as a classroom visual aid—project the diagram on a screen while discussing sentence structure. Students can input their own writing to analyze grammar visually. The download feature lets you save diagrams for worksheets or presentations. ESL instructors find it helpful for showing how English word order differs from students' native languages. We recommend pairing the tool with grammar lessons on parts of speech, sentence types, and syntactic roles for maximum educational impact.