🖼 Cornice Size Calculator
Find finished width, face drop, projection, sheet count, and support spacing for a clean bedroom window finish.
📋 Cornice presets
🔧 Cornice inputs
📈 Cut list and reference tables
| Part | Cut size | Qty | Notes |
|---|
| Window span | Side add | Face drop | Projection |
|---|---|---|---|
| 24-36 in | 3-4 in | 8-10 in | 3-4 in |
| 36-60 in | 4-6 in | 10-12 in | 4-5 in |
| 60-96 in | 5-7 in | 12-14 in | 5-6 in |
| 96-132 in | 6-8 in | 14-18 in | 6-8 in |
| Span | Spacing | Support count | Note |
|---|---|---|---|
| 24-48 in | 28-32 in | 2 supports | Light span |
| 48-72 in | 24-28 in | 3 supports | Add center brace |
| 72-96 in | 20-24 in | 4 supports | Heavy span |
| 96-132 in | 18-22 in | 5 supports | Long wall run |
| Scenario | Width | Drop | Use |
|---|---|---|---|
| Small guest room | 36-42 in | 10-11 in | 4 in |
| Queen bedroom | 48-60 in | 11-12 in | 5 in |
| Primary suite | 60-84 in | 12-14 in | 5-6 in |
| Wide wall span | 84-120 in | 14-18 in | 6-8 in |
| Material | Density | Sheet wt | Best use |
|---|---|---|---|
| Painted plywood | 34 lb/ft3 | 27 lb | Most box cornices |
| MDF | 47 lb/ft3 | 38 lb | Smooth paint finish |
| Solid pine | 29 lb/ft3 | 24 lb | Light decorative trim |
| Foam core | 6 lb/ft3 | 5 lb | Very light pelmets |
| Upholstered shell | 9 lb/ft3 | 8 lb | Soft wrapped fronts |
| Trim composite | 24 lb/ft3 | 20 lb | Humidity-tough spans |
Choosing the right size of cornice matters more than many folks believe Measure from the floor to the highest spot of the ceiling to find the right size. At sloping or vaulted ceilings measure to the peak so that the cornice fits well and looks great. If it is too small or too big for the ceiling, that can ruin the look of the room.
General rule: higher ceilings need bigger profiles. In galleries and big hallways you usually use big to very big cornice, while in small rooms and bathrooms you use medium to small. For apartments with low ceilings small cornices work best.
How to Choose the Right Cornice Size
Are some useful guidelines for sizes. 55 mm cornice works for 2400 mm ceilings. 75 mm goes well with 2550 mm ceilings, and 90 mm for 2700 mm.
75 mm is not bad at 2400 mm, but 90 mm here is clearly too big. That counts for around 95 % of homes with cornice. At 2740 mm is 75 mm the standard size, while 90 mm costs a bit mroe.
The diagonal surface of the cornice shows most, but you do not measure the size by it. Use the drop and projection to avoid ordering too small or too big. At cornices of 100 mm the width of the face is 100 mm.
Coved cornices come in standard sizes, so measure the depth to ensure that you buy the right stuff.
Medium plaster coving and cornices suit many styles of rooms. They range from 80 mm to 120 mm, between classic plain cornices and ogee coving. The most popular sizes of plaster coving fall between 90 mm and 120 mm.
Think, should the cornice stand out or blend in. Traditionally you put big, bold cornices in main reception rooms to impress guests.
One important thing: 90 mm cornices of different brands differ by some millimeters from each other. One brand maybe does not fit where another sits perfectly, so check before. Some profiles with cyma recta form come in total heights of 4.625 inches and 6 inches, with depths of 5.16 inches and 6.7 inches.
Add cornice on top of bookcases for a nice touch. Do first L-shaped build from chipboard, and glue later polyurethane stucco-profile to the front. Cut the chipboards best to size at the local hardware store.
Cornice on top and reused skirting below hide any gaps and fit the piece into the room. Start at one corner of the room and measure every wall separately.
