Learn Hardcore Indonesian: Saya mengganti tirai kamar karena tirai lama sudah kusam. - I change the room’s curtain because the old curtain is already dull.

It means “to replace” (swap out the old item for a new one). If you say mengganti tirai, you’re replacing the curtains. Use mengubah for changing a property (e.g., the color) without swapping the item itself.

What’s the difference between "mengganti" and "menggantikan"?

mengganti X (dengan Y): You, the doer, replace X (optionally state the new item with dengan). Example: Saya mengganti tirai lama dengan tirai baru.
menggantikan X: The subject is the substitute that replaces X. Example: Tirai baru menggantikan tirai lama. Avoid forms like Saya menggantikan tirai lama dengan tirai baru in careful/formal usage; many people say it, but standard grammar prefers the two patterns above.

Can I just say "ganti" instead of "mengganti"?

Yes. In everyday speech, ganti is very common: Saya ganti tirai kamar. Mengganti is neutral-to-formal; ganti feels more casual/colloquial.

Do I need "dengan" to mention what I replaced the curtains with?

Yes, use dengan to introduce the replacement: Saya mengganti tirai kamar dengan tirai baru. Without dengan, if you name both items, it sounds incomplete. Another option is two sentences: Saya mengganti tirai kamar. Tirai barunya warna krem.

Is "tirai kamar" natural, or should I say something else?

tirai = curtain (general); gorden/korden = window curtains (very common in daily speech); kerai = blinds/slatted shades.
tirai kamar or gorden kamar both sound natural for “the room/bedroom curtains.”
If you mean a shower curtain, say tirai kamar mandi.
To be very clear: gorden jendela kamar (tidur) = the bedroom window curtains.

Does "kamar" mean any room, or specifically a bedroom?

On its own, kamar often defaults to “bedroom” in casual Indonesian, but it can mean “room” generally. For clarity:

kamar tidur = bedroom
kamar mandi = bathroom
ruang tamu = living room (note the use of ruang for common/shared rooms)

Should it be "tirai lama" or "tirai yang lama"? What’s the difference?

tirai lama = old curtains (adjective directly modifying the noun).
tirai yang lama = the old one(s), emphasizing identity or contrast with the new ones; good when the noun is already known. You can also say yang lama by itself to avoid repeating the noun: “the old one(s).”

Indonesian has no articles—how do I say “the old curtains” vs “some old curtains”?

Context usually handles it. To make it explicit:

tirai lama itu = that/the old curtains (already known)
tirainya / tirai lamanya = often signals definiteness (“the curtains”)
beberapa tirai = some curtains

What does "sudah" add before "kusam"?

Sudah indicates a completed/resulting state: the curtains have already become dull. Variants:

telah (more formal)
udah (colloquial) Negation contrasts:
belum kusam = not dull yet
tidak kusam = not dull (no “yet” implication)

Can I put the “because” part first?

Yes: Karena tirai lama sudah kusam, saya mengganti tirai kamar. Use a comma after the reason clause in writing. Meaning and tone stay the same.

Is "karena" the only way to say “because”?

karena = neutral “because”
sebab = formal/literary “because”
soalnya = colloquial “because/it’s because”
gara-gara = “because of” with a negative/annoying nuance To say “so/therefore”: jadi, makanya, oleh karena itu (more formal)

How do I negate "kusam" correctly?

Use tidak for adjectives: tirai lama tidak kusam. If it hasn’t happened yet, use belum kusam. Don’t use bukan here; bukan negates nouns, not adjectives.

How do I show singular/plural for “curtain(s)”?

Number is usually unmarked:

tirai = curtain/curtains (context decides) To be specific:
dua tirai or dua lembar/helai tirai
For a typical pair: sepasang gorden
Reduplication (tirai-tirai) is possible but less common in everyday speech

How would a passive version look?

Tirai kamar saya diganti karena tirai lama sudah kusam. The curtains are the subject. You can add the agent with oleh (e.g., …diganti oleh saya…), but it’s often omitted.

Why does "mengganti" have “gg,” and how is it pronounced?

It’s meng- + ganti. The prefix meN- becomes meng- before roots starting with g; the root keeps its g, so you see mengg-. Pronounce ngg as [ŋg] (like “sing-ga”). Examples: menggambar, menggosok.

Could I use "mengubah" instead?

Use mengubah when you change a property, not the item:

Saya mengubah warna tirai = I change the curtains’ color (same curtains).
Saya mengganti tirai = I replace the curtains with new ones.

Is "kusam" the right adjective for curtains? How does it differ from similar words?

kusam = dull/lacking luster (looks tired or slightly dirty)
pudar = faded/washed-out color
lusuh = shabby/worn-looking (often for clothes)
usang = worn-out/obsolete
kotor = dirty Your sentence is natural with kusam.

Could "tirai kamar" be mistaken for “shower curtain”?

If you mean a shower curtain, specify tirai kamar mandi. Without mandi, tirai kamar is normally taken as the curtains belonging to a room/bedroom.

How would a natural casual version of the sentence sound?

Aku ganti gorden kamar soalnya yang lama udah kusam. Notes: Aku (informal “I”), gorden (very common word), soalnya (because), udah (colloquial sudah), and the bare verb ganti are all typical in speech.

How do I say exactly what I replaced them with?

Examples:

Saya mengganti tirai kamar dengan gorden baru warna krem.
Saya mengganti tirai kamar dengan kerai bambu. Or make the replacement the subject: Gorden baru menggantikan tirai lama.