Probability adverbs let you say how sure you are that something is true — from a faint maybe to a flat certainly. Dutch has a rich set of them, and they form a fairly clean scale from low to high confidence. Two things make this group worth a dedicated page for English speakers: first, several of these words have no one-to-one English match (vast wel especially); second, and most importantly, when you put one of them at the front of a clause, Dutch's verb-second rule kicks in and the verb comes before the subject — Misschien komt hij morgen, not Misschien hij komt. Getting that inversion right is the single biggest thing on this page.
The probability cline
Here is the scale from least to most certain. The percentages are rough feel, not official values.
| Adverb | English | Rough confidence | Register |
|---|---|---|---|
| misschien | maybe, perhaps | ~50% | neutral |
| mogelijk | possibly | ~50% | neutral / slightly formal |
| wellicht | perhaps | ~50–60% | formal / written |
| waarschijnlijk | probably | ~75% | neutral |
| vermoedelijk | presumably | ~75% | formal / journalistic |
| vast (wel) | surely, bound to | ~85% | informal, spoken |
| zeker | certainly, definitely | ~95% | neutral |
| ongetwijfeld | undoubtedly | ~99% | formal / emphatic |
Misschien regent het straks, neem voor de zekerheid een paraplu mee.
Maybe it'll rain later — take an umbrella just in case.
Hij komt waarschijnlijk rond zeven uur, want er zijn files onderweg.
He'll probably arrive around seven, because there are traffic jams on the way.
Dat is ongetwijfeld de beste oplossing die we hebben.
That is undoubtedly the best solution we have.
The headline rule: fronting triggers inversion
Dutch is a verb-second (V2) language: in a main clause, the finite verb must be the second element, no matter what sits first. A probability adverb is a perfectly good first element — and when you put one there, it takes the first slot, so the verb comes next and the subject is pushed to after the verb. This is inversion, and English does not do it.
| 1st slot | Verb (2nd) | Subject | Rest |
|---|---|---|---|
| Misschien | komt | hij | morgen. |
| Waarschijnlijk | heeft | ze | het al gehoord. |
| Hij | komt | — | misschien morgen. |
Misschien komt hij morgen langs.
Maybe he'll come by tomorrow. (front 'misschien' → verb 'komt' second → subject 'hij' after it)
Waarschijnlijk weet zij het antwoord wel.
She probably knows the answer.
Zeker krijgen jullie je geld terug, daar zorg ik voor.
You'll certainly get your money back — I'll see to that.
You can also leave the adverb in the middle of the sentence, after the verb and subject. Then there is no inversion, because the subject came first:
Hij komt misschien morgen langs.
He'll maybe come by tomorrow. (subject first → normal order, no inversion)
Ze weet het waarschijnlijk al lang.
She probably already knows it.
Vast (wel): the "I'm pretty sure" marker
Vast is the one with no clean English equivalent. As a probability adverb it means roughly surely / I'm sure / bound to — high confidence, but based on reasoning rather than knowledge. You say Hij komt vast wel when you have good reason to expect him, not when you have been told. It is warm, reassuring, very spoken, and almost always pairs with wel: vast wel.
Maak je geen zorgen, het komt vast wel goed.
Don't worry, it'll surely be fine.
Ze hebben vast al gegeten, het is al negen uur.
They've surely already eaten — it's already nine.
Je hebt het vast druk gehad vandaag.
You've surely had a busy day.
Beware: vast has a completely different everyday meaning as an adjective/separable prefix — vast = "fixed, stuck, permanent" (een vaste baan, a permanent job; de deur zit vast, the door is stuck). As a sentence adverb of probability it is unstressed and usually followed by wel. Context keeps them apart.
Zeker: certainly — and a question particle
Zeker means certainly / definitely / for sure. Fronted, it inverts like the rest. But note a second, distinctively Dutch use: dropped into a yes/no question, zeker turns it into a "I assume this is the case, right?" question — like English tag …right? or I take it….
Je bent zeker moe na die lange reis?
You're tired after that long trip, I take it? / You must be tired, right?
Dat heb jij zeker gedaan!
You did that, didn't you! / I bet you did that!
Here zeker is not stating certainty about a fact; it is signalling that the speaker strongly suspects the answer is yes. This is a flavour English handles with intonation and tags, which is why learners miss it.
Misschien is not "eens"
A frequent confusion: misschien (maybe) versus eens. They are unrelated. Eens is not a probability word at all — it means once / sometime / one day (and, as a modal particle, softens a request: Kijk eens! — Have a look!). Do not let the vague "some-" feeling of misschien pull you toward eens.
Misschien ga ik volgend jaar naar Japan.
Maybe I'll go to Japan next year. (probability)
Ik wil ooit / eens naar Japan.
I want to go to Japan someday. (indefinite time, NOT probability)
Common Mistakes
❌ Misschien hij komt morgen.
Incorrect — a fronted probability adverb triggers V2 inversion; the verb must come second, before the subject.
✅ Misschien komt hij morgen.
Maybe he'll come tomorrow.
❌ Waarschijnlijk het regent straks.
Incorrect — same inversion rule: after fronted 'waarschijnlijk', the verb 'regent' comes before the subject 'het'.
✅ Waarschijnlijk regent het straks.
It'll probably rain later.
❌ Misschien ik ga eens naar Japan.
Two errors — missing inversion, and 'eens' (someday) is not 'maybe'. Front-misschien inverts, and probability ≠ indefinite time.
✅ Misschien ga ik volgend jaar naar Japan.
Maybe I'll go to Japan next year.
❌ Het komt zeker wel goed.
Wrong word for reassurance — 'zeker' overclaims certainty; the natural reassuring marker is 'vast wel'.
✅ Het komt vast wel goed.
It'll surely be fine.
❌ Hij is meer waarschijnlijk laat.
Incorrect — Dutch doesn't say 'meer waarschijnlijk'; 'waarschijnlijk' already means 'probably', and 'more likely' is 'waarschijnlijker'.
✅ Hij is waarschijnlijk laat.
He's probably late.
Key Takeaways
- The cline runs misschien/mogelijk → wellicht → waarschijnlijk/vermoedelijk → vast wel → zeker → ongetwijfeld, low to high confidence.
- A probability adverb at the front of a main clause triggers V2 inversion: verb second, subject after it — Misschien komt hij.
- In the middle of the sentence (after subject + verb), there is no inversion — Hij komt misschien morgen.
- vast (wel) = "I'm pretty sure / bound to," based on reasoning; don't confuse it with adjective vast (fixed/stuck).
- zeker also works as a question particle: Je bent zeker moe? = "You must be tired, right?"
- misschien (maybe) is not eens (someday) — probability versus indefinite time.
Now practice Dutch
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Start learning Dutch→Related Topics
- Dutch Adverbs: OverviewA2 — The big picture for the Adverbs group: the main types (manner, time, place, degree, and sentence/modal adverbs); the headline fact that Dutch adverbs never inflect — no -e ending, unlike attributive adjectives; that the plain adjective IS the manner adverb (no -ly to add); and the time–manner–place ordering, which is the exact reverse of English's manner–place–time.
- Sentence Adverbs: Helaas, Gelukkig, Natuurlijk, BlijkbaarB1 — Whole-sentence comment adverbs that voice the speaker's stance on the entire statement — helaas (unfortunately), gelukkig (fortunately), natuurlijk (of course), blijkbaar/kennelijk (apparently), hopelijk (hopefully) — and why putting one at the front of a Dutch clause triggers verb-second inversion: 'Helaas kan ik niet komen'.
- Verb-Second (V2) in Main ClausesA1 — The backbone of Dutch main clauses — the finite verb sits in the second position, where 'position' means the second constituent, not the second word.
- Inversion After a Fronted ElementA2 — When anything but the subject opens a Dutch main clause, the subject and finite verb swap — including the hallmark 'verb-comma-verb' collision after a fronted subordinate clause.
- Ja, Nee, Wel, Toch, Jawel: Affirmation and ContradictionB1 — Dutch's polarity system — ja/nee, the positive polarity word 'wel' that English lacks (the counter to niet), 'toch' for contradiction and 'after all', and 'jawel' for answering a negative question with yes — including the crucial 'Kom je niet?' → 'Jawel!' pattern.