Rommet er dobbelt så stort.

Rommet means the room. The base noun is et rom = a room.

Norwegian often adds the definite article to the end of the noun:

• et rom = a room
• rommet = the room

So Rommet er dobbelt så stort is talking about one specific room, not just any room.

Because rom is a neuter noun: et rom.

Adjectives in Norwegian often change form to match the noun:

• en stor bil = a big car
• et stort rom = a big room

Since rom is neuter, the adjective takes the -t form: stort.

Dobbelt så ... means twice as ....

So:

• dobbelt så stort = twice as big
• literally, something like double so big

This is a very common Norwegian pattern:

• dobbelt så lang = twice as long
• dobbelt så dyrt = twice as expensive
• dobbelt så raskt = twice as fast

In Norwegian, så is part of the comparison pattern så ... som, which corresponds to English as ... as.

For example:

• Rommet er så stort som kjøkkenet = The room is as big as the kitchen
• Rommet er dobbelt så stort som kjøkkenet = The room is twice as big as the kitchen

In your sentence, the second part is simply left out because it is understood from the context:

• Rommet er dobbelt så stort = The room is twice as big

Normally, the full pattern is:

dobbelt så + adjective + som + comparison

Example:

• Rommet er dobbelt så stort som badet.

But if the thing being compared with is already known, Norwegian can leave som ... out:

• Rommet er dobbelt så stort.

English does the same sometimes:

• The room is twice as big.

So the sentence is complete even without som.

Here, dobbelt functions as a degree modifier, similar to how twice works in English. It modifies the whole expression så stort.

So in practice, it tells you how much bigger the room is.

You do not need to think of it as a normal adjective describing rommet directly. It is more like a quantity/intensity word in this sentence.

Yes. To ganger så stort also means twice as big.

Compare:

• Rommet er dobbelt så stort.
• Rommet er to ganger så stort.

Both are correct. Dobbelt så stort is very common and natural.

It can mean either big or large. In many cases, stor/stort covers both English words.

So this sentence could be understood as:

• The room is twice as big
• The room is twice as large

Both are good English translations.

No, this is normal Norwegian word order for a simple statement:

• Rommet = subject
• er = verb
• dobbelt så stort = complement

So the structure is:

Subject + verb + description

This is very similar to English:

• The room is twice as big.

The dictionary form is stor.

Adjectives are usually listed in their basic form, and then they change depending on grammar:

• stor = basic form
• stort = neuter singular
• store = plural / definite

Examples:

• en stor stol
• et stort rom
• store rom

Yes. Stort is general and can refer to size in whatever sense the context suggests.

For a room, it often means:

• floor area
• overall spaciousness
• general size

So unless the context is very technical, Rommet er dobbelt så stort simply means the room is twice the size of something else in a general sense.

You would add som plus the thing you are comparing it with:

• Rommet er dobbelt så stort som det andre rommet.
• Rommet er dobbelt så stort som kjøkkenet.

This makes the sentence fully explicit:

• The room is twice as big as the other room
• The room is twice as big as the kitchen

Then the adjective would change form.

For example, with a common-gender noun:

• en bil = a car
• Bilen er dobbelt så stor. = The car is twice as big.

With a neuter noun:

• et rom = a room
• Rommet er dobbelt så stort.

So the difference is:

• stor with common gender
• stort with neuter gender