Possible and probable are both correct, but they express different judgments. Use possible when something can happen, be true, or be done. Use probable when the available facts make something likely.
A possible result may still be unlikely. A probable result is not certain, but you have a reason to expect it.
Quick Answer
Possible means “able to happen, exist, be true, or be done.” It does not tell the reader how likely the outcome is.
Probable means “likely to happen or be true,” often because evidence, experience, or current conditions point toward it.
A power outage is possible whenever a storm approaches. It becomes probable when strong winds have already damaged nearby lines.
Why People Confuse Them
Both words describe something that is not certain and often appear before nouns or after “it is.”
However, possible sets a wide boundary: the outcome is not ruled out. Probable makes a narrower judgment: the outcome is expected. Ordinary English does not assign a fixed percentage to either word.
Key Differences At A Glance
- Possible: The event can happen; its likelihood may be high, low, or unknown.
- Probable: The event is considered likely, though not certain.
- Possible: Also describes ability or feasibility: “It is possible to finish today.”
- Probable: Usually expresses an evidence-based expectation: “A delay is probable.”
Meaning and Usage Difference
Possible has two main uses. It can describe an outcome that may occur: “Snow is possible tonight.” It can also describe something that can be achieved: “It is possible to submit the form online.”
Probable focuses on likelihood. “Snow is probable tonight” means current conditions make snow likely. “The probable cause” means the cause most strongly supported by the evidence, without claiming final certainty.
Both words are mainly adjectives. They can modify nouns, as in “a possible route” and “a probable outcome.” They also fit that-clauses: “It is possible that the office will close” and “It is probable that the office will close.”
Tone, Context, and Formality
Possible is common in conversation, requests, planning, and professional writing. It sounds open because it leaves the likelihood undecided.
Probable often sounds more analytical and fits forecasts, investigations, reports, and careful predictions. Neither word guarantees an outcome. Probable expresses more confidence, but it still leaves room for a different result.
Which One Should You Use?
| Context | Best Choice | Why |
| An outcome is not ruled out | Possible | You are stating that it can happen |
| Evidence points toward an outcome | Probable | You believe it is likely |
| A task can be completed | Possible | The issue is ability or feasibility |
| Naming the expected cause or result | Probable | The issue is an evidence-based judgment |
| You do not know the odds | Possible | You should not imply stronger confidence |
| Several options could work | Possible | Each option is available, not necessarily expected |
Use this test: Are you saying can, or are you saying likely? Choose possible for can and probable for likely.
When One Choice Sounds Wrong
Probable sounds wrong when you mean that something can be done:
Incorrect: “Is it probable to change my appointment?”
Better: “Is it possible to change my appointment?”
Possible may be too weak when strong evidence supports one outcome:
Weak: “A shipping delay is possible; the highway is already closed.”
Clearer: “A shipping delay is probable because the highway is closed.”
Also, “It is probable that the train will be late” sounds more natural than “The train is probable to be late.”
Common Mistakes (and Quick Fixes)
Treating the words as exact synonyms: Use possible for an available outcome and probable for an expected one.
Assuming possible means unlikely: Possible does not set the odds. Something may be both possible and probable.
Treating probable as certain: Probable still allows doubt.
Giving probable a universal percentage: Let context show the prediction’s strength unless a field defines a threshold.
Everyday Examples
- It is possible to renew your license online.
- Rain is possible this afternoon, but the forecast remains uncertain.
- Based on the interview, a second round seems probable.
- The probable delivery date is Friday.
- Remote work is possible for this position.
- A price increase is probable after the supplier raised its rates.
- Several explanations are possible, but one is more strongly supported.
- The team can still qualify, although that result is not probable.
Dictionary-Style Word Details
Verb
Possible: Not commonly used as a verb in standard US English.
Probable: Not commonly used as a verb in standard US English.
Noun
Possible: Not commonly used as a standalone noun in standard US English. Use possibility for the noun idea.
Probable: Can be a noun for a person or thing considered probable, especially in specialized reporting. The adjective is much more common.
Synonyms
Possible: Closest plain alternatives include achievable, feasible, conceivable, and potential, depending on context. A clear antonym is impossible.
Probable: Closest plain alternatives include likely, expected, and sometimes plausible. A clear antonym is improbable.
Example Sentences
Possible: “Is a Tuesday delivery possible?” “One possible explanation is a billing error.”
Probable: “The probable winner will be announced after the final count.” “It is probable that demand will rise.”
Word History
Possible: Came through French from Latin possibilis, connected with being able.
Probable: Came from Latin probabilis, related to testing, approving, or proving.
The histories reflect the contrast: possible centers on ability; probable centers on a reasoned judgment.
Phrases Containing
Possible: as soon as possible; whenever possible; if possible; possible cause; possible solution; best possible result.
Probable: probable cause; probable outcome; probable winner; most probable explanation; highly probable; increasingly probable.
FAQs
Yes. Probable expresses a stronger expectation that something will happen or be true. Possible only says the outcome can happen or cannot be ruled out. However, probable still falls short of certainty, so it should not describe a confirmed result.
Yes. A person could possibly win a large lottery prize, but that outcome is not probable. The event is allowed by the rules, yet the chance remains low. This contrast is one of the clearest ways to separate the words.
Yes. An outcome can be possible because it can occur and probable because the evidence makes it likely. For example, rain may be both possible and probable when dark clouds, radar data, and a strong forecast point toward it.
No universal percentage applies in ordinary conversation. Probable generally means likely, but its exact strength depends on context. Some legal, medical, scientific, or business settings may define the word more precisely, so follow the stated standard in those settings.
Use possible to when discussing whether an action can be done: “It is possible to reschedule.” Probable to is often awkward. When expressing likelihood, use a that-clause: “It is probable that the meeting will be rescheduled.”
No. Formal writing benefits from keeping the distinction clear. Possible identifies an available or feasible outcome, while probable identifies the outcome supported as likely. Replacing one with the other can make a report sound either too uncertain or too confident.
Conclusion
Use possible when something can happen, exist, be true, or be done. Use probable when evidence or circumstances make an outcome likely.
The simplest memory aid is direct: possible means can; probable means likely. Because likely does not mean certain, probable still leaves room for doubt.
