When talking about the future in English, we rarely know exactly what is going to happen. Instead, we use different words to show how confident we are. Whether you are 100% sure about a future plan or just guessing, mastering the grammar of future certainty is essential for clear communication.
In this comprehensive guide, we will break down how to use modal verbs, adverbs, and key phrases to express different degrees of certainty about the future.
1. Using Modal Verbs and Adverbs
Combining the future modal verb will (or won’t) with adverbs like definitely and probably is one of the easiest ways to show your level of certainty.
🔴 Very Sure (100% Certainty)
When you have absolutely no doubt about a future event, use will definitely for positive statements and definitely won’t for negative statements.
- Positive: People will definitely work from home more in the future.
- Negative: Robots definitely won’t replace all human jobs.
- ⭐ Bonus Example: I will definitely be at the meeting, don’t worry.
⚠️ Word Order Alert: Notice that definitely goes after “will” in positive sentences, but before “won’t” in negative sentences!
🟠 Sure (80%–90% Certainty)
If you feel confident about an outcome based on a strong feeling or current evidence, use will, really will, or won’t.
- Positive: Donna will really enjoy this film.
- Negative: You won’t regret it.
- ⭐ Bonus Example: I’m confident that prices will drop next month.
🟡 Almost Sure (70%–80% Certainty)
When you think something is highly likely but there is still a small margin of doubt, use probably.
- Positive: We ‘ll probably finish the project by tomorrow.
- Negative: He probably won’t have enough time.
- ⭐ Bonus Example: It probably won’t rain later according to the weather forecast.
🟢 Not Sure (50% or Less Certainty)
When you are uncertain or just guessing, use might, may, or could. For negatives, use might not or may not.
- Positive: I might go to the party, but I’m not sure yet.
- Negative: He hasn’t studied much, so he might not pass the exam.
- ⭐ Bonus Example: The traffic is bad, so the flight could be delayed.
⚠️ Grammar Tip: We don’t usually use could not to talk about future uncertainty. Stick to might not or may not.
2. Using Advanced Phrases and Expressions
To make your English sound more natural and sophisticated, you can use specialized phrases, structures, and specific opinion verbs instead of just relying on “will”.
🔴 Very Sure
- be bound to / be certain to: Used when something is guaranteed to happen due to a natural law or an inevitable pattern.
- He’s bound to feel nervous before his driving test.
- She’s certain to get that job!
- be certain that: He’s certain that he’ll get here on time.
- there’s no chance / way that:
- There’s no chance that we’ll ever win the lottery.
- There’s no way that my boss will give me the day off.
🟠 Sure
- I’m sure that…
- I’m sure that you’ll do well in the interview.
- Are you sure that you won’t be available?
🟡 Almost Sure
- be likely to / be unlikely to:
- The government’s likely to call an election soon.
- Ali’s unlikely to be invited to the party.
- ⭐ Bonus Example: She’s likely to say yes if you ask nicely.
- there’s a good chance / not much chance that:
- There’s a good chance that it’ll snow this week.
- There’s not much chance that I’ll finish this essay tonight.
- think / don’t think / doubt:
- She thinks he’ll be able to help.
- I don’t think we’ll have petrol-based cars in the future.
- I doubt they’ll have any trouble finding the address.
🟢 Not Sure
- there’s a chance that…
- There’s a chance that she’ll be back at work tomorrow.
- There’s a chance that he might come and visit us next week.
- think… might / not sure that…
- I think we might see more of these problems in the next few years.
- I’m not sure that I’ll be able to finish this pizza!
Summary Reference Table
| Degree of Certainty | Positive Expressions | Negative Expressions |
| 100% (Very Sure) | will definitely, be bound to, be certain to | definitely won’t, there’s no way/chance |
| 85% (Sure) | will, will really, I’m sure that | won’t, I’m sure… won’t |
| 75% (Almost Sure) | will probably, be likely to, good chance | probably won’t, be unlikely to, doubt |
| 50% or less (Not Sure) | might, may, could, there’s a chance | might not, may not, I’m not sure that |
Interactive Practice Exercise
Test your knowledge! Choose the correct phrase to complete each sentence based on the level of certainty indicated in the brackets.
- The sky is completely clear. It ─── rain today. (100% Certainty / Negative)
- She has a fever, so she ─── come to school tomorrow. (75% Certainty / Negative)
- I haven’t decided yet, but I ─── buy a new laptop this weekend. (50% Certainty / Positive)
(Drop your answers in the comments section below to see if you got them right!)
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