Japanese Agricultural Standard (JAS) Calculator

Spike VM

Formula developed by the Japanese Ministry of Agriculture and Forestry.

Measuring Log Length

Lengths are measured in metres and tenths of metres and rounded down to each fixed-length class

Measuring Log Diameter

For small-end diameters less than 14 cm
Measure the shortest small-end diameter inside the bark through the centre of the log. Round down to the nearest whole centimetre.
Example: 12.00 - 12.99 cm, enter 12 cm
For small-end diameters equal to and greater than 14 cm
Measure the shortest small-end diameter inside the bark through the centre of the log.
Round down to the nearest even 2-cm interval.
Example: 16.00 - 17.99 cm, record as 16 cm
Japanese Agricultural Standard (JAS) Scale
If the short axis is between 14 and 40 cm, add 2 cm to the short axis for every 6 cm of difference. If the short axis exceeds 40 cm, add 2 cm to the short axis for every 8 cm of difference.
Example:

S=16.00 -  L=22.99 cm, record as 18 cm
S=16.00 -  L=32.99 cm, record as 28 cm
S=42.00 -  L=45.99 cm, record as 42 cm
S=41.00 -  L=49.60 cm, record as 43 cm


Diameter Measured Inside Bark = DIB
Length of Log in Metres M
DIB Measured Small End cm

Results:

Log Volume in Cubic Metres

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