What are "Should" and "Shouldn't" in English Grammar?
Should and its negative form shouldn't (should not) are modal verbs used primarily to give advice, make recommendations, and state weak obligations or expectations.
When you use should, you are telling someone what you believe is the "right", "proper", or "best" thing to do in a situation. It is much softer and less demanding than must or have to.
As true modal verbs, should and shouldn't do not change their form based on the subject (there is no "-s" added for third person), and they are strictly followed by a bare infinitive (a verb without "to").
"Should" and "Shouldn't" Structure and Formula
The formula for should is consistent across all subjects.
Standard Formula:
- Positive: Subject + should + base verb + Object
- Negative: Subject + shouldn't / should not + base verb + Object
- Question: Should + Subject + base verb + Object?
Pedagogical shorthand:
- (+) S + should + V(bare) + O
- (-) S + shouldn't + V(bare) + O
- (?) Should + S + V(bare) + O?
How to Form "Should" and "Shouldn't"
Positive (Affirmative) Sentences
Use should to give positive advice or state an expectation.
| Subject (S) | Modal | Main Verb (V_bare) | Object/Complement |
|---|---|---|---|
| You / We | should | see | a doctor about that cough. |
| The parcel | should | arrive | by tomorrow morning. |
Example: You should really read this book; it's fantastic.
Negative Sentences (Seeking to Prevent)
Use shouldn't to advise against doing something, or to say a behavior is a bad idea.
| Subject (S) | Modal | Main Verb (V_bare) | Object/Complement |
|---|---|---|---|
| I / He / She | shouldn't | eat | so much sugar before bed. |
| You | shouldn't | drive | if you are feeling tired. |
Example: We shouldn't waste so much electricity.
Yes/No Questions and Asking for Advice
Invert the subject and the modal to politely ask for someone's opinion or advice.
| Wh- Word | Modal | Subject | Main Verb (V_bare) | Object/Complement |
|---|---|---|---|---|
| (none) | Should | I | call | him right now? |
| What | should | we | wear | to the interview? |
Short Answers: Yes, you should. / No, you shouldn't.
When to Use "Should" and "Shouldn't" in English
1. Giving Advice and Recommendations
This is the most common use. You are expressing an opinion about what is best for the other person.
- You should drink at least eight glasses of water a day.
- You shouldn't work so late; you need more sleep.
2. Moral Obligation / Weak Duty
Use should to describe the "right thing to do" based on morals or social norms, even though it isn't legally mandated.
- People should be kind to one another.
- He should apologize for his rude behavior yesterday.
3. State an Expectation (Probability)
Use should to state that something is highly likely to happen because it is logical or planned. (Note: Only use the affirmative should for this, not the negative).
- The train left an hour ago, so it should be arriving any minute now.
- It should be warm enough to go to the beach tomorrow.
Common Signal Words for "Should"
- When giving advice: in my opinion, I think you should, it would be a good idea to...
- When expecting something: probably, by now, according to the schedule, I expect...
- When asking for help: What do you think I should...?, Do you think we should...?
How to Tell the Difference Between "Should" and Similar Grammar Topics
"Should" vs. "Must" or "Have To"
This is a question of strength.
- Should: Weak obligation. It is a good idea, but there is no serious punishment if you ignore it. (You should exercise more.)
- Must / Have To: Strong obligation. It is a hard rule, and there will be consequences (legal, health, or professional) if you ignore it. (You must wear a seatbelt while driving.)
"Should" vs. "Should Have"
- Should: Present or general advice. (You should study for the test tomorrow.)
- Should have + V3: Past regret or criticism for an action that did not happen. (You failed the test. You should have studied yesterday!)
"Should" vs. "Ought to"
- Grammatically, they mean exactly the same thing (advice/weak obligation).
- Should is significantly more common in modern spoken English and is much easier to use in questions (Should I go? vs. Ought I to go?).
Common Mistakes with "Should" and "Shouldn't"
- ❌ Mistake: Adding an "-s" to the modal for third-person singular.
- Incorrect: He shoulds go home.
- Correct: He should go home.
- ❌ Mistake: Using "to" after the modal verb.
- Incorrect: You should to eat more vegetables.
- Correct: You should eat more vegetables.
- ❌ Mistake: Using a continuous or past tense verb after the modal.
- Incorrect: Should you speaking right now?
- Correct: Should you speak right now?
- ❌ Mistake: Using should forcefully for absolute rules.
- Incorrect: Guests should not steal items from the hotel! (Too soft/polite).
- Correct: Guests must not steal items from the hotel!
Real-life Examples of Usage
- (Advice): You should try the seafood restaurant near the port; their fish is delicious.
- (Negative Advice): I think you shouldn't tell him the bad news until he finishes his exams.
- (Asking for Advice): Should I book the plane tickets in advance to get a better price?
- (Expectation): The board meeting should finish by 5:00 PM.
- (Moral Duty): Students should read all the assigned chapters before attending the seminar.
- (Asking for Advice): What time should we meet at the cinema tonight?
- (Negative Advice): You shouldn't leave your laptop unattended in a public cafe.
- (Moral Duty): She should really apologize; what she did to her friend was wrong.
- (Expectation): We followed the recipe perfectly, so the cake should taste amazing.
- (Negative Advice): We shouldn't waste so much perfectly good food.
Summary & Cheatsheet for Should and Shouldn't
| Meaning/Context | Modal | Formula Structure | Example |
|---|---|---|---|
| Positive Advice | should | S + should + V(bare) | You should rest. |
| Negative Advice | shouldn't | S + shouldn't + V(bare) | You shouldn't smoke. |
| Moral Obligation | should | S + should + V(bare) | People should be fair. |
| Expectation | should | S + should + V(bare) | The bus should arrive soon. |
| Asking Advice | should | Wh- + should + S + V(bare)? | What should I do? |
Frequently Asked Questions
Can I use "Should" to talk about the past?
No. If you say "I should write," you are giving advice for the present or future. To talk about the past, you must fundamentally change the grammar structure to the modal perfect: "I should have written" (See dedicating topic: Should have / Could have / Would have).
Is it polite to use "you should"?
It depends on the context and tone of voice. If someone asks for your opinion, "you should" is perfectly polite. However, if you offer unprompted advice, saying "you should..." can sometimes sound bossy or critical. A softer, more polite alternative is "Maybe you could..." or "It might be a good idea to...".