Log Weight Calculator — Weight of a Wood Log
Estimate how much a round wood log weighs: enter the diameter and length, choose the species, and get the approximate weight in kilograms and pounds — modelling the log as a solid cylinder.
cm
m
Wood species
Cylinder approximation using air-dry wood density (≈ 15% moisture content)
127.2 kg
- 1
Radius (diameter ÷ 2 ÷ 100)
30 ÷ 2 ÷ 100 = 0.15 - 2
Log volume (π × r² × length)
π × 0.15² × 2.5 = 0.1767 - 3
Log weight (volume × density)
0.1767 × 720 = 127.2
How does this calculator work?
Weight = π × (diameter/2)² × length × wood_density. A 30 cm diameter, 2.5 m oak log (air-dry 720 kg/m³) weighs about 127 kg. Densities are for air-dry wood (≈ 15% moisture); green wood is 40–100% heavier.
Formula
How this is calculated
A round log is closely approximated by a solid cylinder. The volume is V = π × r² × L, where r is the radius (half the mid-point diameter in metres) and L is the length in metres. Multiplying the volume in cubic metres by the wood's density in kg/m³ gives the mass in kilograms. This approach is known as Huber's formula in timber measurement and is the most accurate single-measurement method for a tapered trunk.
Densities listed are for air-dry wood at approximately 15% moisture content, sourced from the Forest Products Laboratory Wood Handbook (2021) and Hoadley's "Understanding Wood" (2000). Green (freshly felled) wood contains significantly more water — oak, for example, can be 40–100% heavier when freshly cut. Kiln-dried wood at 8% moisture may be 5–15% lighter than the air-dry estimate. If your log was recently felled, expect the actual weight to be noticeably higher.
Use the custom density option if you know your species' actual density from a specific reference or from a sample measurement (immerse a small piece in water and use Archimedes' principle).
Frequently asked questions
Most likely because the wood is green (freshly cut) and still contains its natural moisture. Green oak can weigh 50–100% more than air-dry oak at 15% moisture content. Let the wood season for 1–2 years in a covered, ventilated stack; the weight will drop substantially and the heat output per kg will increase.
Wrap a measuring tape around the log's circumference at the mid-point and divide by π (≈ 3.14159) to get the diameter. Alternatively, measure the widest and narrowest diameters and average them. The mid-point diameter gives the best representative figure for Huber's formula.
Huber's formula (cylinder at mid-diameter) is accurate for modestly tapered logs — typically within 1–3% of the true volume. For strongly flared butts, Smalian's formula (average of top and base cross-sections × length) or Newton's formula (a weighted combination) gives higher precision, but requires two diameter measurements.
Also known as
TG we-Calculate Editorial Team. (2026). Log Weight Calculator — Weight of a Wood Log [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/log-weight-calculator
TG we-Calculate Editorial Team. "Log Weight Calculator — Weight of a Wood Log." TG we-Calculate. 2026. https://we-calculate.com/calculator/log-weight-calculator.
TG we-Calculate Editorial Team, "Log Weight Calculator — Weight of a Wood Log," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/log-weight-calculator
@misc{wecalculate_log_weight_calculator, title = {Log Weight Calculator — Weight of a Wood Log}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/log-weight-calculator}}, year = {2026}, note = {TG we-Calculate} }
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