Terminbeløpet øker i den grad den effektive renten stiger.

Because Norwegian normally writes compound nouns as a single word.

Here, terminbeløpet is built from:

• termin = a payment period / installment term
• beløp = amount

So the whole noun means the amount for that payment term or installment. English often uses several words where Norwegian uses one compound word.

A useful rule: in Norwegian compounds, the last part is the main noun. So beløp tells you that the whole word is a kind of amount.

-et marks the noun as singular definite for a neuter noun.

So:

• et terminbeløp = an installment amount
• terminbeløpet = the installment amount

This is very common in Norwegian: the definite article is often attached to the end of the noun instead of being a separate word.

I den grad is a fixed expression meaning to the extent that, insofar as, or in proportion as.

It does not just mean when or if. It shows a relationship of degree: the first thing changes depending on how much the second thing changes.

So this phrase suggests a proportional idea, not just a simple condition.

In i den grad, den is just part of the fixed expression. It is not working like the in normal English.

You can think of i den grad as a chunk that you learn as a whole. Historically, it is something like in that degree, but in modern Norwegian it functions as an idiomatic expression meaning to the extent that.

So the first den is different from the den in den effektive renten.

Because this is a definite noun phrase with an adjective.

In Bokmål, when a noun is definite and has an adjective before it, you usually get:

• den/det/de
  • adjective + noun in definite form

So:

• effektiv rente = effective interest rate
• den effektive renten = the effective interest rate

This pattern is often called double definiteness, because both the article and the noun show definiteness.

Renten is definite because it refers to a specific interest rate, not the idea of interest rates in general.

Compare:

• effektiv rente = effective interest rate, as a general term or category
• den effektive renten = the specific effective interest rate being discussed

In financial writing, Norwegian often uses the definite form when the context makes it clear which rate is meant.

The part den effektive renten stiger functions as a subordinate clause after the expression i den grad.

In this sentence, the word order looks the same as in a main clause:

• den effektive renten stiger

But that is only because there is no sentence adverb like ikke.

If you add ikke, you can see the difference more clearly:

• Main clause: Den effektive renten stiger ikke.
• Subordinate clause: ... i den grad den effektive renten ikke stiger.

So after a subordinating expression, Norwegian typically places ikke before the finite verb.

Yes, both can often be translated as increase, go up, or rise.

But they are not used in exactly the same way all the time:

• å stige often means to rise and is very common with things like prices, rates, temperatures, and levels
• å øke is more general and often works well with amounts, quantities, and measurable changes

So:

• renten stiger sounds very natural
• terminbeløpet øker also sounds very natural

Using two different verbs also avoids repetition and makes the sentence sound smoother.

Yes. This sounds fairly formal and fits financial or legal language well.

Especially formal-sounding parts are:

• terminbeløpet
• i den grad
• den effektive renten

A more everyday version might use a different structure, depending on the exact meaning you want. For example:

• Jo mer den effektive renten stiger, desto mer øker terminbeløpet.
• Hvis den effektive renten stiger, øker terminbeløpet.

These are not always identical in nuance:

• i den grad emphasizes extent/proportion
• hvis gives more of a simple if condition