How Much Does OSB Weigh?

Oriented strand board (OSB), or chipboard or flakeboard as it’s sometimes referred to, is a popular engineered sheet material used for wall panels, subfloors, and roof sheathing.

OSB features thin strands of veneer bonded in a cross-oriented pattern, giving the board its trademark look, dimensional stability, and high strength.

In this article, we’ll take an in-depth look at the weight of OSB, and we’ll also compare its weight to popular alternatives such as plywood and MDF.

The weight of a 4-ft x 8-ft OSB sheet ranges from about 26.5 lbs (1/4″ thick) to almost 120 lbs (1-1/8″ thick). A metric 2440mm by 1220mm OSB sheet weighs from around 11.5 kg (6mm thick) to 72.5 kg (38mm thick). OSB is approximately 31% heavier than softwood plywood but about 9% lighter than MDF.

Whether you’re working with imperial or metric OSB, keep reading to find helpful reference tables of the weights of standard OSB sheet sizes and thicknesses. We’ve also included a handy OSB calculator to help you figure out the weight of custom sheet sizes too.

How Much Does OSB Weigh?

As you’ll see below, a 1/2″ thick, 4′ x 8′ feet sheet of OSB is approximately 31% heavier than softwood plywood but about 9% lighter than MDF sheets of the same size.

Because of its increased weight and density versus plywood, even a slight increase in the thickness of an OSB sheet can lead to pretty sizeable weight increases.

From how much a sheet weighs in both imperial and metric measurements to how much OSB weighs per square foot, here’s everything you need to know about the weight of OSB:

How Much Does a Sheet of OSB Weigh?

For those in the United States, or anyone working with imperial sizing, the weight of a standard 4′ x 8′ OSB sheet ranges from around 26.5 lbs (1/4″ thickness) to almost 120 lbs (1-1/8″ thickness).

Here’s a full summary of the approximate weight of the same 4-foot by 8-foot sheet of OSB across a variety of imperial thicknesses:

For readers outside the United States, or anyone working with metric sizing, the weight of a standard 2440mm by 1220mm OSB sheet ranges from around 11.5 kg (6mm thickness) to almost 72.5 kg (38mm thickness).

Here’s a full summary of the approximate weight of the same 2440mm by 1220mm OSB sheet across a variety of metric thicknesses:

How Much Does OSB Weigh per Square Foot?

The table below provides a summary of approximate weights for OSB on a square foot basis.

The weights have been calculated based on an average OSB density of approximately 39.95 lb/ft3 (converted from the average 640 kg/m3 referenced here).

How Much Does OSB Weigh per Square Meter?

The table below provides a summary of approximate weights for OSB on a square meter basis.

As above, the weights have been calculated based on an average OSB density of 640 kg/m3 (i.e., the average of the 600-680 kg/m3 range referenced here).

OSB vs. Plywood Weight

Like OSB, plywood is another common engineered sheeting material that is highly versatile.

Plywood is manufactured from thin veneers of wood, with each layer cross-grained and glued at 90-degrees to the piece below to give the wood its trademark stability and strength.

Several varieties of plywood are available, and each has different properties suited to various applications.

OSB is typically heavier than plywood, particularly versus softwood, hardwood, and premium baltic birch plywood variants. Pressure-treated plywood is one type of plywood that tends to be heavier than OSB, however.

Here’s a summary table that shows how much OSB weighs versus comparably-sized plywood sheets:

OSB Density – An Overview

The density of an object or construction material is a measure of its mass per unit volume.

Both the density and the volume (the size in terms of length, width, and thickness) therefore impact the mass (in other words, weight) of an OSB sheet.

As mentioned above, OSB has a typical average density of 39.95 lb/ft3.

For reference, poplar plywood has a density of approximately 515 kg/m3, making these sheets much lighter overall, while standard MDF has an average density of around 700 kg/m3 leading to a heavier sheet versus OSB.

Why Is OSB So Dense?

OSB sheets typically consist of 95% wood fibers bonded together using wax and synthetic resins.

The thin strands of veneer (usually pine) are bonded in three cross-oriented (in other words, at 90-degrees to each other), giving the OSB excellent dimensional stability and superior strength versus MDF.

A contributing factor to OSB’s relatively high density is its lack of void or knots that you’d find in cheaper plywood, with these defects lowering the density and weight of these boards.

It’s worth mentioning that it is possible to find OSB sheets with a lower density than the average 39.95 lb/ft3, which reduces the overall weight of the sheet.

While the lighter weight can be beneficial in terms of making the sheet easier to handle, it can impact the mechanical properties of the OSB, for example, through reductions in overall strength, air tightness, and water resistance.

How Do You Calculate the Weight of OSB?

A simple way to work out the weight of OSB is by using the weight per square foot reference table above (for imperial weights, i.e., lbs).

The first step is to work out the square foot area of the sheet you want to figure out the weight of, with a 4-foot by 8-foot sheet having an area of 32 square feet, for example (calculated by multiplying the two dimensions together).

Next, you’ll need to know the weight per square foot, which looking at a 3/4″ OSB sheet for this example is 2.49 lbs/ft² as per the reference table above.

The final step is to multiply the sheet area (32 square feet, in this case) by the weight per square foot (2.49 lbs/ft² for this example) to give a sheet weight of approximately 79.68 lbs.

The process is the same for metric weights (i.e., kilograms), but you’ll need to use the weight per square meter table above instead.

For example, if you multiply the sheet area of 2.9768m² (for a standard 2440mm x 1220mm sheet) by 11.52 kg/m² for an 18mm OSB sheet, you’ll get an approximate sheet weight of 34.29 kg.

Alternatively, a much quicker and easier way to calculate the weight of a sheet of OSB is by using the simple OSB weight calculator below.

OSB Weight Calculator

Need to work out how much a sheet of OSB weighs in either imperial or metric units? Use our simple OSB weight calculator:

Final Remarks

Oriented strand board (OSB) is typically heavier than plywood but lighter than MDF. A 1/2″ thick 4-foot by 8-foot sheet of OSB weighs around 53 lbs, for example, versus about 40.5 lbs for a softwood plywood sheet and 58 lbs for an MDF sheet of the same size.

Because of its increased weight versus plywood, another popular sheeting material, OSB may require a larger supporting structure to deal with the increased weight, which could add additional complexity or expense to your project.

Another potential disadvantage of OSB’s increased weight is that it can be harder to lift and maneuver, especially when dealing with thicker full sheet sizes or working by yourself.

We’ve included handy weight tables above that you can use to check the approximate weight of both metric or imperial sheet sizes, and you can use the calculator to figure out how much OSB weighs in custom sheet sizes, too.