Understanding Log Measure Standards in Different Countries (Part 1)

According to incomplete statistics, in North America alone, there are nearly 100 different log measurement methods, with a total of 185 different names. Below are some common measurement methods used around the world, particularly those exported to China.

1) JAS gauge

(Full name: Japanese agricultural standard)

--Established by the Japanese Ministry of Agriculture and Forestry in 1841 (the second year of the Opium War)

--Widely applicable to importing countries such as New Zealand/Australia/Chile/Japan

--Round length to the next decimeter. Measure the diameter of the shortest diameter of the smaller end. For logs under 14cm, round to the next centimeter (e.g., 11.8cm is counted as 11cm). Round over 14cm to the next even-numbered centimeter (e.g., 17.8cm is counted as 16cm). Note that this is "rounding down," not "rounding off." Although only the short diameter of the smaller end is measured, if the log is "extremely flat," meaning the difference between the long and short diameters of the smaller end exceeds 6cm, add 2cm to the recorded value.

--Formula (different formulas are used for those below 6m and above!)

Below 6m: (D²xL)/10000

Over 6m: Add a coefficient of (length - 4)/2 to the diameter and then use the above formula.

2) Russian GOST gauge (full name: Russian GOST 2708-75)

The standard is very close to the Chinese national standard, the main differences are:

--Length: China uses 0.2m increments, while the Russian standard reserves a 3cm margin and rounds up to 0.25m. Any shortfall is discarded, but special lengths of 3.8m, 7.6m, and 8m are retained.

--Diameter: The Chinese standard takes the average of the shortest diameter and its perpendicular diameter; the Russian standard takes the average of the shortest diameter and the longest diameter.

--Both methods refer to the volume table for results (but the formulas behind them are slightly different).

In short, the actual inspection results are probably:

12-24cm increases by 10%; 26-40cm increases by 5%; 42-52cm increases by 1.5%; above 54cm, the size starts to increase!

3) SMALIAN ruler

--Measure the size of the head and calculate the average area

--The Canadian BC METRIC introduced in the previous issue is a typical SMALIAN gauge

--Formula: (Small head area + Large head area) x Material length/2

4) HUBER gauge

-- Common in European countries and Gabon, Africa

--At 1/2 of the material length, the amount of skin (this rule has certain disadvantages)

--The material length is divided into sections according to multiples of 2.7-3.0 meters and the allowance and defects are deducted.

--Formula: Calculated as a cylinder, just like the smalian, i.e.: middle cross-sectional area x length/2

Therefore, in theory and practice, the same log will have different results when measured by Smalian and Huber. For example, a log with a small end of 25cm, a large end of 31cm, and a length of 5m will have different results when measured by Smalian and Huber.

Smalian’s understanding:

Calculation results:

(0.125²+0.305²)*3.1416*5=0.311m3

HUBER's understanding:

Calculation results:

0.14² *3.1416*5=0.308m3

5) ATIBT standard (full name: Association Technique Internationale des Bois Tropicaux)

Commonly found in Africa, South America, Papua New Guinea, etc.

Similar to the SMALIAN ruler, the difference is that the length and short diameters of the log heads are measured and the average of the four data is used as the "average diameter" to calculate the volume.

The above five methods, plus the North American 1,000-board-foot measurement (introduced in the previous issue), are the most common methods for measuring the length of imported logs.

Tomorrow's next one-minute series will introduce some other various methods of measuring rulers.