Tarkistan reitin kartasta ennen lähtöä.

I check the route on the map before leaving.

Breakdown of Tarkistan reitin kartasta ennen lähtöä.

• minä: I
• ennen: before
• -sta: from
• tarkistaa: to check
• reitti: route
• kartta: map
• lähtö: leaving

Questions & Answers about Tarkistan reitin kartasta ennen lähtöä.

Why is tarkistan in this form—what tense/person is it?

Tarkistan is the 1st person singular (I) form of the verb tarkistaa (to check / to verify). It’s in the present tense, which in Finnish also often covers the near future (so it can mean “I check” or “I’m going to check,” depending on context).
Conjugation pattern: tarkistaa → tarkistan.

Why isn’t there a word for I (minä) in the sentence?

Finnish usually doesn’t need subject pronouns, because the verb ending already shows the person. Tarkistan clearly signals I.
You can add minä for emphasis/contrast: Minä tarkistan reitin… (“I check…”, as opposed to someone else).

Why is reitti in the form reitin?

Reitin is the object in the -n form, commonly described as genitive/accusative singular. With many verbs (including tarkistaa), Finnish often marks a “complete/finished” object this way: you check the whole route, not just “some of it.”

When would it be reittiä instead of reitin?

You’d use reittiä (partitive) if the action is not seen as complete, or if it’s ongoing/partial, or in certain other environments (negatives, etc.). For example:

• Tarkistan reittiä kartasta. = “I’m checking the route (looking it over / not necessarily as a completed ‘full check’).”
• En tarkista reittiä. = “I’m not checking the route.” (negative typically takes partitive)

Why is kartasta used—what case is that?

Kartasta is elative case (-sta/-stä), meaning “out of / from inside”. With many information sources in Finnish, elative is used to mean “from” that source:

• kartasta = “from the map” (i.e., using the map as the source of information)

Could it also be kartalla instead of kartasta?

Sometimes, yes, but it changes the nuance:

• kartasta (elative) emphasizes getting/reading the information from the map
• kartalla (adessive, “on/at the map”) can sound more like using the map as a tool/location, closer to “on the map” literally
  For “check from a map,” kartasta is very natural.

What exactly does ennen do grammatically, and why is lähtöä not lähtö?

Ennen means “before” and it typically requires the following noun to be in the partitive case.
That’s why lähtö (“departure”) becomes lähtöä (partitive): ennen lähtöä = “before departure.”

Could I say ennen lähtöäni to mean “before my departure”?

Yes. Ennen lähtöäni is a very natural way to specify “before my departure,” using a possessive suffix:

• lähtöä = departure (partitive)
• -ni = “my”
  So: Tarkistan reitin kartasta ennen lähtöäni.

Is there any special reason for the word order Tarkistan reitin kartasta ennen lähtöä?

This is a neutral, very typical order: verb + object + source + time.
Finnish word order is flexible, though, and you can move parts to emphasize them:

• Ennen lähtöä tarkistan reitin kartasta. (emphasizes “before departure”)
• Kartasta tarkistan reitin ennen lähtöä. (emphasizes “from the map”)

How do I know that reitin is singular, and what would plural look like?

Reitin is singular (“the route”). Plural would be:

• reitit = routes (nominative plural)
• reitit as a “total object” in plural is often the same form as nominative plural in many contexts, but you’ll also see case-marked plurals depending on structure.
  A simple plural version could be: Tarkistan reitit kartasta ennen lähtöä. = “I check the routes from the map before departure.”

What’s the difference between reitti and matka here?

Reitti is specifically the route/path/itinerary (the way you go).
Matka is the trip/journey itself.
So Tarkistan reitin… is “I check the route…”, while Tarkistan matkan… would be more like checking details of the trip (less precise for “route”).

Why is it lähtöä and not something like a verb form (“before leaving”)?

Finnish often expresses “before doing X” using ennen + noun (partitive) rather than a gerund. Lähtö is a noun meaning “departure,” so ennen lähtöä neatly matches “before leaving/before departure.”
You can also express “before I leave” with a clause: ennen kuin lähden (“before I leave”), but that’s a different structure.