Eu não sei medir tempo.

I don't know how to measure time.

Breakdown of Eu não sei medir tempo.

• eu: I
• não: not
• o tempo: the time
• saber: to know
• medir: to measure

Questions & Answers about Eu não sei medir tempo.

Why is medir in the infinitive form here? Why not something like eu não sei meço tempo?

In Portuguese, when one verb expresses ability / knowledge how to do something, it is usually followed by another verb in the infinitive (the “dictionary form”).

• saber + infinitive = to know how to (do something)
  
  • Eu sei medir. = I know how to measure.
  • Eu não sei medir tempo. = I don’t know how to measure time.

You cannot conjugate the second verb in this structure:

• ❌ eu não sei meço tempo
• ✅ eu não sei medir tempo

So medir must stay in the infinitive after sei here.

Can I drop the Eu and just say Não sei medir tempo?

Yes.

Portuguese is a “null subject” language: the subject pronoun (like eu, I) is often omitted because the verb ending carries the information about the person.

• Eu não sei medir tempo.
• Não sei medir tempo.

Both mean exactly the same. Using eu can add slight emphasis to I in contrast to others (I don’t know how to measure time, maybe others do), but grammatically both are correct and natural.

Why is não placed before sei? Can it go anywhere else?

The basic rule is:

não + conjugated verb

So in this sentence:

• sei is the conjugated verb
• não goes directly before it

✅ Eu não sei medir tempo.

You cannot move não to other positions like:

• ❌ Eu sei não medir tempo. (wrong)
• ❌ Eu sei medir não tempo. (wrong)

In simple tenses, não almost always stands right before the main conjugated verb.

Why is there no article before tempo? Why not Eu não sei medir o tempo?

Both forms can occur, but there is a nuance.

1. Without article – generic / abstract sense

   • Eu não sei medir tempo.
     More abstract: I don’t know how to measure time / I’m no good at dealing with time in general.

2. With article – more specific or concrete

   • Eu não sei medir o tempo.
     Can sound a bit more like I don’t know how to measure (the) time, referring to time as a particular quantity or “thing” (for example, in a technical context).

In everyday speech, dropping the article with an abstract, mass-like concept such as tempo is very typical and sounds natural in European Portuguese.

Does tempo here mean “time” or “weather”?

In Portuguese, tempo can mean time or weather, depending on context.

In this sentence:

• Eu não sei medir tempo.
  It clearly means time, because we typically talk about measuring time, not measuring weather.

For “weather” with tempo, you’d normally use a different verb:

• O tempo está bom. = The weather is good.
• Como vai estar o tempo amanhã? = What will the weather be like tomorrow?

So here, you should understand tempo as time (duration, passing of time).

Is Eu não sei medir tempo the most natural way to say “I’m bad at keeping track of time” in European Portuguese?

It’s understandable and correct, but depending on what you mean, you might also hear:

• Eu não tenho noção do tempo.
  = I have no sense of time / I lose track of time.
• Sou péssimo(a) a gerir o meu tempo.
  = I’m terrible at managing my time.
• Não sei gerir bem o meu tempo.
  = I don’t know how to manage my time well.

Eu não sei medir tempo sounds a bit more literal or technical ("I don’t know how to measure time”), but in context it can also be taken more loosely as “I’m not good with time.”

How do you pronounce Eu não sei medir tempo in European Portuguese?

A rough phonetic approximation (European Portuguese) is:

• Eu → like “eh-oo” mashed a bit, often reduced: [ew] or [eu]
• não → nasal sound, like “now” but with nasal “ow”: [nɐ̃w]
• sei → like “say”: [sēj] (closer to [sɐj] for many speakers)
• medir → [mɨˈdiɾ]
  
  • me- → [mɨ] (a very reduced vowel, like a short “uh”)
  • -dir → [diɾ], with an r that is a light tap, like the Spanish r in pero
• tempo → [ˈtẽpu]
  
  • tem- → [tẽ], nasal vowel (like “ten” but nasalized)
  • -po → [pu]

Spoken fairly naturally:

Eu não sei medir tempo. → approximately “Ew nãw say mɨ-DIR TÊ-pu”

What’s the difference between saber and conhecer? Why is it sei medir and not conheço medir?

Portuguese has two main verbs for “to know”:

1. saber – knowing facts, information, skills, how to do something

   • Eu sei medir tempo. = I know how to measure time.
   • Eu sei a resposta. = I know the answer.

2. conhecer – being familiar with people, places, works, things

   • Eu conheço Lisboa. = I know Lisbon / I am familiar with Lisbon.
   • Eu conheço o João. = I know João.

So for “know how to (do something)”, you must use saber + infinitive:

• ✅ Eu sei medir tempo.
• ❌ Eu conheço medir tempo. (incorrect)

Is the sentence the same in Brazilian Portuguese?

Grammatically, yes. In Brazil you can also say:

• Eu não sei medir tempo.

Main differences:

• Pronunciation:
  
  • Brazilian Portuguese will have clearer vowels: [ew nãw ˈsej meˈd͡ʒiʁ ˈtẽpu]
  • The r in medir is usually a guttural [ʁ] (like French r) in most Brazilian accents.
• Vocabulary alternatives might differ a bit:
  • BP: Eu não sei administrar o meu tempo.
  • EP: Eu não sei gerir o meu tempo.

But your original sentence is valid in both varieties.

Can I change the tense to say “I didn’t know how to measure time”?

Yes. You mainly have two past tenses to consider:

1. Imperfect (sabia) – past state / ongoing situation

   • Eu não sabia medir tempo.
     = I didn’t know how to measure time (over a period in the past).

2. Perfect (soube) – past moment of realisation / discovery

   • Eu não soube medir o tempo.
     = I didn’t manage to measure the time / I failed to measure the time (in a specific situation).

For “I didn’t know how (generally, in that period of my life)”, the imperfect:

• Eu não sabia medir tempo.

is usually what you want.