Wood Volume vs Wood Weight

reservoir logs sell wood by approximate volume (metre cubed or m3)

Weights of logs can vary within these volumes.  The weight can vary dramatically as it is affected by:

  • tree species
  • moisture content
  • wood density
  • log length
  • log shape/uniformity

We use a variety of differently sized net bags and this is made clear on the listing for the product.  Thus the packaging dictates the finished product. 

We have developed our firewood products from feedback from existing and new customers.  We endeavour to give you, the customer what you want and to exceed your expectations.

The stated volumes and weights are taken from an overall average of our products and are for guidance only.  Average weights and volumes of products may vary as may the packaging.  

Due to the restrictions of selling online being almost unanimously based upon weight, the following parameters have been applied to the quotes for delivery of logs both nationally and locally:

All 40 Litre Nets of kiln dried logs, regardless of type of wood are given a weight of 15kgs.  As per the characteristics shown above this weight may vary by 5kg either way.  

All 30 Litre Nets of kiln dried logs, regardless of type of wood are given a weight of 10kgs.  Again, this may vary depending on variables.

A popular misconception is that a "builders bag" also known as a "tonne bag" or a "bulk bag" is a cubic metre or "a tonne" of wood.

Firstly, builders bags come in many dimensions the most popular being 90cm x 90cm x 90cm = 0.729m3 (or three quarters of metres cubed).  When the logs are "loose" in this bag depending on the length this can give a stacked volume of approx half a cubic metre of stacked logs with no spaces.

This makes 12 x 40 Litre nets of logs (25cm long) the same as a builders bag and 24 the equivalent of a stacked cubic metre.  

The industry calculation for determining the volume of loosely bagged logs is to fill the bag with logs and then weigh the bag. The weight of the logs can then be converted to volume using the following formula:

Volume (in cubic meters) = Weight (in kilograms) / Density (in kilograms per cubic meter)

The density of wood varies depending on the species, but a common value used in the industry is 700 kilograms per cubic meter. This means that if you weigh a bag of loosely bagged logs and it weighs 350 kilograms, the volume of the logs would be:

Volume (in cubic meters) = 350 kilograms / 700 kilograms per cubic meter = 0.5 cubic meters

It is important to note that this method is based on the assumption that the logs are packed tightly in the bag and that there is no air space between them. If the logs are not packed tightly, the calculated volume may be higher than the actual volume.

In addition to weighing the bag, you can also estimate the volume of loosely bagged logs by visually filling the bag and measuring the dimensions. However, this method is less accurate and may not provide as reliable results as weighing the bag.

It is important to always check the volume of logs you would receive when purchasing a builders bag, also known as a bulk bag or tonne bag, because the size of the bag can vary. A builders bag can be either 100cm x 100cm x 100cm or 90cm x 90cm x 90cm, which can significantly impact the amount of logs you receive.

For example, a 100cm x 100cm x 100cm builders bag has a volume of 1 cubic meter, while a 90cm x 90cm x 90cm builders bag has a volume of 0.729 cubic meters. This means that if you purchase a builders bag without checking the size, you may end up with significantly more or less logs than you expected.

To avoid any confusion or disappointment, it is always a good idea to check the volume of the builders bag before making a purchase. This will help you to accurately determine how many logs you will receive and ensure that you are getting the best value for your money.

How much is a cubic meter of logs?  Standard Logs (10" or 12cm) = 25 nets average 16-20 logs per net approximately 400 logs per cubic metre