Japanese Curtain Sizes Explained: How to Measure and Buy Ready-Made Curtains
Ready-made curtains in Japan are sold per panel, usually 100 cm wide, in lengths of about 135 cm (waist-high windows), 178 cm and 200 cm (floor-length balcony windows). Measure the width of the curtain rail and multiply by about 1.05 to allow for gathers; that total covers both panels. For length, measure from the rail hook ring to where you want the curtain to end — about 1 cm above the floor for balcony windows.
Standard sizes
- Width: 100 cm per panel is the most common. A pair (2枚組) covers a rail of about 180–190 cm.
- Length 135 cm: for waist-high windows (腰窓).
- Length 178 cm: for taller windows.
- Length 200 cm: for floor-length balcony windows (掃き出し窓).
- Other sizes are available as made-to-order (オーダー) at a higher price.
How to measure
Width: measure the rail from end to end and multiply by 1.05. Divide by two for each panel of a pair.
Length for a waist-high window: from the ring of the rail runner to about 15–20 cm below the bottom of the window frame.
Length for a balcony window: from the ring of the rail runner to about 1 cm above the floor.
Blackout grades (遮光等級)
- 遮光1級: the strongest — the room becomes dark enough to sleep in daytime.
- 遮光2級: dim, with faces still visible.
- 遮光3級: shaded, but you can tell it is daytime.
- Lace curtains (レースカーテン) go behind for privacy in the day; ミラーレース makes the inside harder to see from outside.
Fire-retardant curtains in tall buildings
Under Japan's Fire Service Act, buildings taller than 31 m (about 11 storeys and above) must use fire-retardant curtains, marked 防炎 with a label. If you live in a tower block, choose curtains labelled 防炎.
Picks with checked prices
-
Blackout curtains 100×200 cm (pair)
カーテン 4枚セット 防音 コーティング 断熱 遮光1級 アゲインスト 厚地2枚組＋選べるミラーレース 2枚組セット 4枚組 幅100cm×丈110cm(108
¥5,980（サンロック@インテリア · checked 2026-10-24）
Why this one: The standard size for floor-length balcony windows.
Check on the item page: 遮光1級 = strongest blackout. 幅100×丈200 = per panel. 2枚組 = a pair. 形状記憶 = pleats hold their shape.
View on RakutenOther price levels: Budget ¥2,499Premium ¥12,590
-
Blackout curtains 100×135 cm (pair)
【マラソン期間クーポン有】 ★遮光カーテン アウトレット 2枚組 カーテン 遮光 お買い得 遮光カーテン祭り 2枚セット 既製品 幅100cm×丈135 178
¥2,189（カーテン天国 · checked 2026-10-24）
Why this one: The standard size for waist-high windows (腰窓).
Check on the item page: 丈135 = 135 cm long. Check 遮光1級 and 2枚組.
View on RakutenOther price levels: Budget ¥2,499Premium ¥10,560
-
Mirror lace curtains (pair)
【最大2,880円OFF】10/24 20:00〜10/27 9:59省エネ節電レース カーテンくれない レースカーテン K-wave-L-total high
¥4,830（カーテンメーカーくれない直販店 · checked 2026-10-24）
Why this one: Hangs behind your blackout curtains; in daytime it lets light in while making the room hard to see into.
Check on the item page: ミラーレース = mirror lace. UVカット = blocks UV. 遮熱 = keeps summer heat out.
View on RakutenOther price levels: Budget ¥1,610Premium ¥7,530
-
Fire-retardant blackout curtains
【最大2,880円OFF】10/24 20:00〜10/27 9:59省エネ節電カーテン カーテン くれない 「K-wave-D-plain」40色 遮光カーテ
¥5,780（カーテンメーカーくれない直販店 · checked 2026-10-24）
Why this one: Required in buildings over 31 m tall; check for the 防炎 label.
Check on the item page: 防炎 = fire-retardant (with an official label). 防炎ラベル付き = comes with the label.
View on RakutenOther price levels: Budget ¥2,980Premium ¥19,020
FAQ
- What size curtains do I need for a Japanese balcony window?
- Usually a pair of 100 cm × 200 cm panels, but measure your rail and floor height first. Floor-length curtains should end about 1 cm above the floor.
- What does 遮光1級 mean?
- The highest blackout grade in Japan. The room becomes dark enough that faces are hard to see.