Quick answer: Allow is followed by object + to-infinitive: She allowed him to leave. Let is followed by object + bare infinitive (no “to”): She let him leave. Allow is also more formal than let. For a fuller definition, see the Cambridge Dictionary entry for ‘allow’.
Comparison Table
| Word | Register | Grammar Pattern | Example |
|---|---|---|---|
| allow | formal / neutral | allow + object + to-infinitive | They allowed us to enter. |
| let | informal / neutral | let + object + bare infinitive | They let us enter. |
Using Allow
Allow is the more formal verb. It means to give permission or to make something possible. It is followed by an object and then a to-infinitive. Allow can also be used in the passive: Smoking is not allowed.
The teacher allowed the students to use dictionaries.
Mobile phones are not allowed in the exam hall.
Please allow two weeks for delivery.
The new law allows companies to operate remotely.
Allow for
The phrasal verb allow for means to take something into account: Allow for possible delays. This meaning is not shared by let.
Using Let
Let is the more informal verb for giving permission. It is followed by an object and a bare infinitive (the verb without “to”). Let does not work well in the passive and is rarely used in formal writing.
Let me know when you arrive.
Her parents let her stay out late.
Don’t let it bother you.
Let the mixture cool before serving.
Let in Set Expressions
Let appears in many common fixed expressions: let alone, let go, let down, let it be. These are idiomatic and not interchangeable with allow.
Common Mistakes
✗ Let me to explain.
✓ Let me explain.
Note: let always takes a bare infinitive — no “to”.
✗ He was let to leave early.
✓ He was allowed to leave early.
✗ They allowed him leave.
✓ They allowed him to leave.
Also confusing: Attempt vs Try, Advise vs Advice, Already vs Yet. Browse all confusing word pairs →
Quick Check: Allow or Let?
Four questions — choose the correct option.
1. “Visitors are not ___ to take photographs.”
2. “___ me know if you have any questions.”
3. “Her parents ___ her to stay out until midnight.”
4. “Don’t ___ the fire go out.”
Frequently Asked Questions
What is the difference between allow and let?
Both mean to give permission, but they use different grammar. Allow is followed by object + to-infinitive: “She allowed him to go.” Let is followed by object + bare infinitive (no “to”): “She let him go.”
Do I use “to” after let or allow?
Use “to” after allow: “allow someone to do something”. Do NOT use “to” after let: “let someone do something” (bare infinitive). Saying “let him to go” is incorrect.
Is allow more formal than let?
Yes, allow is generally more formal than let. In written English, formal contexts, rules, and regulations, allow is preferred. Let is more common in everyday spoken English.
Can I say “let me to go”?
No. After let, always use the bare infinitive (without “to”): “Let me go”, “Let him speak”, “Let them decide”. Never “let me to go”.
Can “allow” be used in passive voice?
Yes. Allow works well in the passive: “Smoking is not allowed”, “He was allowed to leave early”. Let cannot easily be used in the passive in the same way.
What is the passive of let?
Let does not have a common passive form. Instead, use allow in the passive: “He was allowed to leave” (not “He was let to leave”). In informal speech, “let go” is occasionally used passively in set phrases.
Can “let” be used in formal writing?
Let appears in formal writing mainly in set expressions: “let it be known”, “let this serve as notice”, “let there be no doubt”. For general permission in formal writing, prefer allow.
What does “allow for” mean?
“Allow for” means to take something into account or to make provision for it: “Allow for delays when planning your journey”, “The budget does not allow for unexpected costs”. Let does not have this phrasal verb meaning.
Are allow and permit synonyms?
Allow and permit are near-synonyms. Permit is slightly more formal and is often used in official or legal contexts: “Parking is not permitted”, “You are not permitted to enter”. Allow is broader and more common in everyday use.
How do allow and let appear in IELTS?
In IELTS writing, allow is more appropriate in formal essays. A common mistake is “let someone to do something” — remember, let takes a bare infinitive. Using both correctly demonstrates grammatical range.