How to Calculate Timber CFT for a Door
CFT (Cubic Feet) is the standard unit used in India’s timber industry to measure and price wood. To calculate the timber needed for a door, you need to account for three components: the frame, the shutter(s), and wastage from cutting and joinery.
A door frame has 2 vertical stiles (jambs) and 1 top horizontal rail. Some doors also have a bottom rail (threshold). Multiply Length x Width x Depth for each member and add them up.
Measure Height x Width x Thickness of each shutter panel. For double-shutter doors, each panel is half the door width.
Real-world cutting, shaping, and joinery always produce some waste. Add 8-10% to your net timber volume to get the practical requirement.
The formula: Total CFT = (Frame CFT + Shutter CFT) + Wastage %
Standard Door Sizes in India
Here are the commonly used door dimensions in Indian residential construction:
| Door Type | Height | Width | Frame Section | Shutters | Approx. CFT |
|---|---|---|---|---|---|
| Main Door | 7 ft | 3.5 – 4 ft | 5″ x 3″ | Double | 5.5 – 7.0 |
| Pooja Room Door | 7 ft | 2.5 ft | 4″ x 3″ | Double | 3.0 – 4.0 |
| Internal Room Door | 7 ft | 3 ft | 4″ x 3″ | Single | 3.5 – 4.5 |
| Bathroom Door | 7 ft | 2.5 ft | 4″ x 3″ | Single | 2.5 – 3.5 |
These are approximate values. Actual CFT depends on the exact frame section, shutter thickness, and whether a bottom frame member is included. Use the calculator above for precise figures.
Frequently Asked Questions
What is CFT?
CFT stands for Cubic Feet. It is the standard measurement unit used in India to calculate the volume of timber. 1 CFT = Length (ft) x Width (ft) x Thickness (ft).
Why is wastage included?
When timber is cut, shaped, and joined to form a door frame and shutter, some material is inevitably lost. Wastage of 8-10% is standard for straightforward doors; carved or profiled doors may need 12-15%.
Should I include the bottom frame?
Main doors and internal room doors typically do not have a bottom rail, allowing a flush finish with the floor. Bathroom and pooja room doors usually include a bottom threshold to contain water or define the space.
How does shutter type affect CFT?
A plain flush shutter uses the calculated CFT directly. Paneled, carved, or profiled shutters require thicker timber stock and produce more waste, so you should increase the wastage percentage accordingly.
What timber species are commonly used for doors?
Teak (Sagwan) is the most popular for main doors due to its durability. Sal, Neem, and Mango wood are common for internal doors. Honne (Matti) and Silver Oak are popular in South India.