🚪 Blackout Curtain Size Calculator
Size the length, overlap, and fabric package for blackout curtains that seal better at the edges.
📌 Blackout presets
⚙ Length settings
📊 Blackout fabric build guide
📝 Length and seal guide
| Target | Offset | Look | Best for |
|---|---|---|---|
| Float | 1 in above | Seal | Sleep rooms |
| Skim | 0.5 in above | Low gap | Bedroom use |
| Kiss | 0 in | Seal | Light seal |
| Apron | 6 in below | Quiet | Small rooms |
| Break | 1 in below | Heavy | Tall rooms |
| Puddle | 4 in below | Dark | Deep blackout |
🧱 Header allowance guide
| Header | Top add | Stack feel | Note |
|---|---|---|---|
| Rod pocket | 3.5 in | Quiet | Blackout header finish |
| Ring clips | 1.25 in | Light | Least top bulk |
| Wave tape | 2.5 in | Even | Neat ripple effect |
| Back tab | 2.0 in | Steady | Hidden hardware look |
| Pleated tape | 3.0 in | Formal | More structured top |
| Hidden tab | 1.5 in | Quiet | Minimal visible header |
📋 Hem and shrink guide
| Hem depth | Shrink | Added length | Use |
|---|---|---|---|
| 2 in | 0-2% | Small | Light blackout |
| 3 in | 2-3% | Medium | Double-lined poly |
| 4 in | 3-5% | Deep | Bedroom blackout |
| 5 in | 5-8% | Large | Heavy blackout |
| 6 in | 8% | Extra | Tall drapes |
📷 Blackout room presets
| Room | Reference | Finish | Panel note |
|---|---|---|---|
| Bedroom | Floor | Skim | Two panels, ring clips |
| Kitchen | Sill | Float | Two panels, rod pocket |
| Living room | Floor | Puddle | Two panels, wave tape |
| Nursery | Sill | Kiss | Quiet, safe, easy care |
| Bay window | Apron | Break | Three or four panels |
| Office | Sill | Skim | Neat, low-dust drop |
💡 Blackout tips
In the United States, curtains of 84 inches long are quite common. Ideally they just barely touch the floor. Short curtains end a few inches below the window sill.
People commonly find also 96 or 108 inches as standard lengths. The panels come in sizes as 54, 63, 84 and 95 inches. Widths range according to quality, from 37 to 52 inches for each panel.
How to Measure and Choose Curtains
Choose the widest for good results although they cost more.
Blackout curtains have standard widths of 42 or 52 inches each panel, with various lengths. Some stores offer more choices for different windows. Curtain measurements always show width first, length second, and you use inches.
Draw the window on paper helps, especially for newcomers.
For measuring, start from the rod to the bottom finish, where curtains will hang. If they rest under the window sill or to the floor, they will block most of light. It is better buy a bit longer than needed.
To stop light, curtains be 1.5 to 2 times wide and 6 to 12 inches longer than the window. Sometimes people advise even 2.5 to 3 times the width.
Specifically for blackout, 2 times the window width will prevent stretch and gaps at the rod when closed. If custom covers cost too much, buy several panels, sew them together or use hemp tape. Raise the rod 2 to 8 inches above the frame is good idea.
Blackout curtains weigh more. For lightweight, 7/8-inch rod works, but 1 1/8 inch gives needed strength for heavy panels. At lengths as 80 inches, extra support in the middle holds the weight and prevent sagging.
Remember the whole weight of curtains with possible blackout linings.
To stop light at edges, extend the rod wider, raise it, add a wrap return, widen panels for good overlap or seal gaps by means of removable clips. Right size for blackout curtains really matters. Portable versions have 62×40 or 86×54 inches and use suction cups for fitting to various windows.
They come in grommet- or rod-pocket styles, where grommet-tops slip easily on metal rods. For fullness, 1.5 times are standard, 2 timesoptional.
