Introduction
Do you ever pause mid-sentence, wondering whether to write “due to” or “because of”? You are not alone. Even advanced English learners often mix these two phrases up, and the difference is subtle but important—especially in formal writing like essays, reports, or business emails. In this guide, you will learn the grammatical rule that separates them, how to apply it step by step, and how to fix the most common mistakes ESL speakers make.
What Is “Due To” vs “Because Of”?
Both “due to” and “because of” explain why something happens or the reason behind a result. They are both prepositional phrases, and in everyday speech, people often use them interchangeably. However, strict grammar rules—especially in academic or professional writing—require a distinction.
“Because of” is an adverb phrase. It modifies a verb, an adjective, or an entire clause. It answers the question “why?” and always follows a verb or a clause that expresses an action or state.
“Due to” is an adjective phrase. It modifies a noun or a pronoun. It means “caused by” or “attributable to.” In formal grammar, “due to” should follow a form of the verb to be (is, are, was, were, has been, etc.) or directly follow a noun.
Rules
- Rule 1: Use “because of” after a verb or a clause. If you can replace the phrase with “caused by” and the sentence still makes sense grammatically, you likely need “due to.” If you can replace it with “for the reason that” or “as a result of,” use “because of.”
- Rule 2: Use “due to” after the verb “to be.” Example: “The delay was due to traffic.” Here, “due to” modifies the noun “delay.”
- Rule 3: Use “due to” directly after a noun. Example: “The cancellation due to bad weather upset everyone.” Here, “due to” modifies the noun “cancellation.”
- Rule 4: Never start a formal sentence with “due to.” In strict grammar, “due to” at the beginning of a sentence is incorrect because it has no noun or “to be” verb to modify. Instead, use “because of” or rephrase the sentence.
- Rule 5: In informal writing or speech, the distinction is often ignored. But for exams like IELTS, TOEFL, or Cambridge, and for professional emails, follow the strict rules.
How to Use It
Follow these simple steps to choose the correct phrase every time.
- Step 1: Identify what comes before the phrase. Look at the word immediately before “due to” or “because of.” Is it a verb (like “happened,” “left,” “failed”)? Or is it a noun or a form of “to be” (is, was, were)?
- Step 2: If the word before is a verb or a full clause, use “because of.” For example: “She stayed home because of her cold.” The verb “stayed” comes before the phrase.
- Step 3: If the word before is a noun or a form of “to be,” use “due to.” For example: “Her absence was due to a cold.” Here, “was” (a form of “to be”) comes before the phrase.
- Step 4: Test with a substitution. Replace the phrase with “caused by.” If the sentence still sounds natural, use “due to.” If not, use “because of.”
- Step 5: For formal writing, avoid starting sentences with “due to.” Instead, write “Because of the storm, the event was cancelled.” Or rephrase: “The cancellation was due to the storm.”
Examples in Sentences
- The match was postponed because of heavy rain. (Verb “was postponed” before the phrase.)
- The postponement was due to heavy rain. (Noun “postponement” before “was.”)
- He failed the exam because of lack of preparation. (Verb “failed” before the phrase.)
- His failure was due to lack of preparation. (Noun “failure” before “was.”)
- We arrived late because of the traffic jam. (Verb “arrived” before the phrase.)
- The traffic jam was due to an accident on the highway. (Noun “jam” before “was.”)
- She couldn’t sleep because of the noise outside. (Verb “couldn’t sleep” before the phrase.)
- The noise was due to construction work. (Noun “noise” before “was.”)
- Many flights were cancelled because of the snowstorm. (Verb “were cancelled” before the phrase.)
- The cancellation of many flights was due to the snowstorm. (Noun “cancellation” before “was.”)
- He resigned because of personal reasons. (Verb “resigned” before the phrase.)
- His resignation was due to personal reasons. (Noun “resignation” before “was.”)
Common Mistakes
Here are the most frequent errors ESL learners make, along with corrections.
- Mistake 1: Starting a sentence with “due to.”
❌ Due to the rain, the game was cancelled.
✅ Because of the rain, the game was cancelled.
✅ The game was cancelled due to the rain. - Mistake 2: Using “due to” after a verb.
❌ She missed the bus due to oversleeping.
✅ She missed the bus because of oversleeping.
✅ Her missing the bus was due to oversleeping. - Mistake 3: Using “because of” after a noun without “to be.”
❌ The delay because of traffic was long. (This is not strictly wrong, but it is awkward.)
✅ The delay due to traffic was long. - Mistake 4: Using “due to” without a form of “to be” or a noun.
❌ He left early due to feeling sick.
✅ He left early because of feeling sick.
✅ His early departure was due to feeling sick. - Mistake 5: Overusing “because of” in formal writing when “due to” is more precise.
❌ The increase in sales was because of the new marketing strategy.
✅ The increase in sales was due to the new marketing strategy.
Quick Summary
- “Because of” = adverb phrase. Use after a verb or a clause. Answers “why?”
- “Due to” = adjective phrase. Use after a noun or a form of “to be.” Means “caused by.”
- Test: Replace with “caused by.” If it fits, use “due to.” If not, use “because of.”
- Never start a formal sentence with “due to.” Use “because of” or rephrase.
- In informal English, the rules are relaxed, but for exams and professional writing, follow them strictly.
Practice Exercises
Fill in the blanks with either “due to” or “because of.” Answers are below.
- The school closed early __________ the storm warning.
- Her success was __________ years of hard work.
- He was tired __________ working late every night.
- The project’s failure was __________ poor planning.
- We missed the flight __________ the long security line.
Answers:
- because of (verb “closed” before the phrase)
- due to (noun “success” before “was”)
- because of (verb “was tired” before the phrase)
- due to (noun “failure” before “was”)
- because of (verb “missed” before the phrase)
Conclusion
Mastering the difference between “due to” and “because of” is a small change that makes a big impression in your writing. Remember the golden rule: “because of” follows verbs, and “due to” follows nouns or “to be.” Practice with the exercises above, and soon this choice will feel automatic. Your future essays and emails will thank you!
FAQ
1. Can I ever use “due to” at the beginning of a sentence?
In formal writing, no. “Due to” is an adjective phrase and needs a noun or a form of “to be” to modify. Starting a sentence with it leaves it dangling without a clear reference. Instead, use “because of” at the start, or rephrase the sentence so that “due to” follows a noun or “to be.” For example, instead of “Due to the delay, we left,” write “Because of the delay, we left” or “The delay was due to traffic, so we left.”
2. Is it true that “due to” is always followed by a noun?
Yes, in strict grammar, “due to” should be followed by a noun or a noun phrase. For example, “due to bad weather” (weather is a noun). You cannot say “due to raining” because “raining” is a verb form. You would say “because of the rain” or “due to the rain” (rain as a noun).
3. What is the easiest trick to remember the difference?
The easiest trick is the “caused by” test. If you can replace the phrase with “caused by” and the sentence still makes sense, use “due to.” If not, use “because of.” For example: “The accident was caused by speeding” → “The accident was due to speeding.” But “He left caused by the noise” does not work, so you say “He left because of the noise.”
4. Are “due to” and “because of” ever interchangeable?
In everyday informal English, yes, most native speakers use them interchangeably without noticing. However, in formal writing, academic papers, and proficiency exams, the distinction is expected. If you are writing an email to a professor, a business report, or an IELTS essay, always follow the strict rules to avoid losing marks or sounding unprofessional.