Complex Sentence Generator
Generate sentences with a dependent clause and a main clause, introduced by words like although, because and when.
- Free
- No sign-up
- Instant
- Runs in your browser
A complex sentence pairs an independent clause with at least one dependent clause — "Although the librarian hesitated, the detective examined the dusty map." This generator produces varied complex sentences for studying subordination.
Subordination is where English sentences start to carry real reasoning. A subordinating conjunction does more than glue clauses together; it defines the logical relationship between them — cause (because, since), time (when, while, after, before), and concession (although). The generator always places the dependent clause first, followed by a comma, which is the pattern most style guides teach first and the one most often tested in exams.
For advanced learners and writing students, a useful exercise is transformation: take a generated complex sentence, identify its two clauses, and rewrite the whole thing as a compound sentence or as two simple ones. Comparing the three versions makes the trade-offs between subordination and coordination concrete in a way definitions never do.
Who this page is for
- Upper-intermediate and advanced English learners studying subordinate clauses.
- Teachers who need fresh examples of concession, cause and time clauses for every lesson.
- Academic-writing students learning to layer reasoning into a single sentence.
- Exam candidates practicing the dependent-clause-first, comma, main-clause pattern.
Popular ways to use it
Advanced Grammar
Practice recognizing subordinating conjunctions and clause boundaries.
Academic Writing
Study how dependent clauses add reasoning and contrast to a sentence.
Sentence Combining
Use examples as models for combining short sentences into richer ones.
Why this generator is different
Instant
Sentences are generated locally in your browser — no network round-trip, no waiting.
Private
Nothing you generate or save ever leaves your device.
Customizable
Control structure, tone, length, tense, vocabulary level and quantity.
Exportable
Copy everything, or download TXT, CSV and JSON for real workflows.
How to use it
Configure
Pick how many sentences you want, then set structure, tone, length, tense and vocabulary — or keep the defaults.
Generate
Click Generate (or press Cmd/Ctrl+Enter). Results appear instantly, and Surprise Me shuffles the settings for you.
Copy or save
Copy single sentences, copy the whole batch, save favorites to your browser, or export TXT, CSV and JSON.
Sentence structures explained
Simple sentences
One independent clause with a subject and a verb: “The teacher opened the notebook.” The building block of all English writing.
Compound sentences
Two independent clauses joined by a coordinating conjunction: “The chef baked a cake, and the children watched eagerly.”
Complex sentences
An independent clause plus a dependent clause: “Although the librarian hesitated, the detective examined the map.”
Frequently asked questions
What is a complex sentence?
A complex sentence contains one independent clause and at least one dependent clause introduced by a subordinating conjunction such as although, because, when or while.
Which subordinators does this tool use?
Although, because, when, while, after, before and since, with the dependent clause placed first followed by a comma.
What is the difference between compound and complex sentences?
Compound sentences join two independent clauses with a coordinating conjunction; complex sentences attach a dependent clause that cannot stand alone.