Wood / Timber Volume (CFT) Calculator
Estimate the volume of round logs and sawn timber in Cubic Feet (CFT) and Cubic Metres (CBM). Includes Hoppus formula and custom pricing estimates.
How to calculate timber volume in CFT?
For Round Logs, the standard commercial formula in India and Bangladesh is the Hoppus Rule: Volume (CFT) = (Girth / 4)² × Length / 144 (with girth measured in inches and length in feet). For Sawn/Cut Wood, the formula is: Volume (CFT) = (Width in inches × Thickness in inches × Length in feet × Quantity) / 144.
🪵 Wood Volume (CFT & CBM) Calculator
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Popular Indian Wood Species Density and Price Guidelines
Reference weight and estimated cost per CFT for standard timber species traded in South Asia (2026 data).
| Wood Species (বাংলা নাম) | Density (kg/m³) | Weight per CFT (approx) | Grade / Quality | Est. Price per CFT (₹) |
|---|---|---|---|---|
| Teak Wood (সেগুন কাঠ) | 650 - 750 kg/m³ | 18 - 21 kg | Premium Hardwood | ₹2,500 – ₹5,000 |
| Sal Wood (শাল কাঠ) | 800 - 900 kg/m³ | 22 - 25 kg | Heavy Structural | ₹1,500 – ₹2,500 |
| Mahogany (মেহগনি) | 550 - 650 kg/m³ | 15 - 18 kg | Medium Furniture | ₹900 – ₹1,600 |
| Pine Wood (দেবদারু / পাইন) | 450 - 550 kg/m³ | 12 - 15 kg | Softwood / Utility | ₹600 – ₹1,000 |
| Jackfruit (কাঠাল কাঠ) | 650 - 700 kg/m³ | 18 - 20 kg | Furniture Hardwood | ₹1,200 – ₹2,000 |
| Mango Wood (আম কাঠ) | 550 - 600 kg/m³ | 15 - 17 kg | Low-cost Hardwood | ₹400 – ₹700 |
Frequently Asked Questions — Wood CFT Calculator
Volume = (Girth / 4)² x Length / 144. This formula is highly popular because it automatically discounts roughly 21.5% of the total cylindrical volume to account for typical bark, curve, and sawmill slab wastage.The Complete Guide to Wood & Timber Volume (CFT) Calculation
Wood remains a fundamental material for construction, flooring, ceiling frameworks, and premium furniture design across South Asia. Whether you are a homeowner getting custom doors crafted, a carpenter planning an interior project, or a timber merchant operating a sawmill, understanding how to calculate wood volume accurately is essential to avoid being overcharged.
In the commercial timber market of India, Bangladesh, and Pakistan, wood is bought and sold using two primary units of volume: Cubic Feet (CFT), which is the traditional and most popular unit of volume, and Cubic Metres (CBM), the international metric unit used for imported timber and large-scale industrial projects.
Wood volume calculations differ significantly depending on the form of the timber: Round Logs (uncut tree trunks) and Sawn Timber (squared logs, planks, and beams). This guide details the mathematics, standard formulas, and commercial practices used to determine timber volume.
How to Calculate Sawn Timber Volume (Size Wood)
Sawn timber refers to wood that has been processed through a sawmill and cut into rectangular shapes (planks, beams, rafters, or blocks). Because the shape is a regular cuboid, calculating its volume is straightforward.
Because length is traditionally measured in feet while width and thickness are measured in inches, the formula is adjusted to output the result directly in Cubic Feet (CFT):
Why Divide by 144? Volume in cubic feet requires all three dimensions to be in feet. To convert width and thickness from inches to feet, we must divide each by 12 (since 12 inches = 1 foot). Multiplying these together yields 12 × 12 = 144. Thus, dividing by 144 is the mathematically correct way to convert square inches multiplied by feet into cubic feet.
Practical Example of Sawn Wood Calculation:
Suppose you purchase 15 pieces of Sal wood rafters for a roof structure, with the following dimensions: Width: 5 inches, Thickness: 3 inches, Length: 14 feet.
If the merchant quotes a rate of ₹1,800 per CFT, the estimated cost is ₹39,375.
How to Calculate Round Log Volume
Round logs are raw, uncut tree trunks. Because tree trunks are roughly cylindrical but have natural tapering (wider at the base, narrower at the top), calculating their commercial wood volume requires specialized formulas. In South Asian markets, two primary methods are used:
Method 1: The Hoppus Quarter-Girth Rule (Standard Commercial Practice)
The Hoppus rule is an old forestry formula designed to estimate the amount of usable square timber that can be sawn from a round log. It automatically discounts the volume lost in bark, curves, and sawmill slab wastage. To apply this formula, you need the log midpoint girth (circumference) in inches and the length in feet:
Method 2: The Actual Cylinder Volume Formula
This calculates the true geometric volume of the cylinder log without discounting any waste. It is used when buying wood for pulping or veneer peeling where the entire round shape is utilized:
The Hoppus Rule: Commercial Waste vs. Geometric Truth
Why do timber merchants insist on using the Hoppus Rule instead of the true cylinder formula? Let us compare the volume of the same round log under both formulas (Girth = 48 inches, Length = 12 feet):
- Hoppus Rule Volume:
Volume = (48/4)² × 12 / 144 = 144 × 12 / 144 = 12.00 CFT - Actual Cylinder Volume:
Volume = 48² × 12 / 1809.56 = 27,648 / 1809.56 ≈ 15.28 CFT
The actual geometric volume is 15.28 CFT, but the commercial volume is calculated as 12.00 CFT. The Hoppus rule discounts roughly 21.5% of the physical volume. This discount is intentional: when a round log is run through a sawmill to create square planks, the outer round sections (slabs) and bark are cut away as waste. The Hoppus rule protects the buyer by charging only for the estimated usable squared timber.
How to Convert Wood Volume: CFT to CBM & CBM to CFT
When dealing with international timber shipments (such as imported Burmese Teak or Malaysian hardwood), volumes are often listed in Cubic Metres (CBM). You will need to convert this to Cubic Feet (CFT) to match local retail rates.
- To convert CFT to CBM: Multiply the CFT value by 0.0283168.
- To convert CBM to CFT: Multiply the CBM value by 35.3147.
Guide to Popular Indian & Bangladeshi Wood Species
When purchasing wood, volume is only half the equation; wood species and density determine its durability, strength, and price. Teak wood (Segun) is highly prized for its water resistance and aesthetic grain. Sal wood is extremely dense and heavy, making it ideal for door frames and structural support. Mahogany is an excellent, budget-friendly hardwood for furniture.
Buying Tips for Homeowners
Always measure log midpoint girth personally using a flexible measuring tape. Ensure that if a log is tapered, you measure at the narrow, wide, and middle points, and take the average. When purchasing sawn timber, inspect for natural knots, splits, and warping, and verify the thickness with a vernier caliper or tape to ensure you are getting the exact sizes invoiced.