Lumber Calculator
About Lumber Calculation
The calculator determines the volume of lumber based on the specified cross-section dimensions and quantity of pieces. This type of calculation is used when purchasing sawn timber, checking the cubic volume of a batch, comparing different sections, and converting the result into cost based on the price per 1 m3.
The calculation is suitable for materials with constant thickness and width along the full length. The result helps quickly determine the volume of each item, the total cubic volume of the batch, and the overall cost without manual unit conversion.
Reference points and recommendations
How the volume of one item is calculated
Geometric model. Each board or timber piece is treated as a rectangular solid with a constant cross-section. The calculator first determines the volume of one piece from thickness, width, and length, and then multiplies the result by the number of identical pieces.
V = T × W × L × n / 1 000 000
Meaning of the formula. Here, T and W are entered in millimeters, L in meters, n in pieces, and the resulting volume V is obtained in m3. Division by 1 000 000 converts the product mm × mm × m into cubic meters, because 1 m2 = 1 000 000 mm2.
Intermediate result. For each line, the calculator determines a separate item volume. This is useful when a batch consists of several standard sizes and the total result must include every group of pieces.
How the total batch volume is determined
Summation of items. After calculating the volume for each line, the calculator adds all obtained values. This produces the total batch volume in m3.
Vtotal = V1 + V2 + V3 + ... + Vk
Logic of the final value. If only one size is used in the calculation, the total volume is equal to the volume of that line. If several sizes are used, the final result is the sum of all lines without additional factors, stacking corrections, or compaction adjustments.
How the cost is calculated
Basic principle. If the price per 1 m3 is given, the calculator multiplies it by the total batch volume. The result is the cost of the entire calculated volume.
C = Vtotal × P
Meaning of the formula. Here, C is the total price, Vtotal is the total volume in m3, and P is the price per 1 m3. This approach follows the common practice of selling sawn timber by cubic volume rather than by weight.
What is not included. The calculation does not include discounts, waste, cutting losses, grading, moisture content, delivery cost, or possible trade surcharges for processing. Therefore, the monetary result shows only the cost of the calculated geometric volume.
Which assumptions are used
Constant cross-section. The calculation assumes that thickness and width do not change along the length of the piece. If the material has noticeable warping, rounded edges, chamfers, grooves, tongues, or another complex shape, the actual timber volume may differ from the calculated value.
Nominal and actual sizes. The calculator uses exactly the values entered by the user. For this reason, the result will differ for a nominal size from a price list and for an actual size after drying, planing, or calibration.
No moisture adjustment. The geometry is not recalculated for a different wood moisture level. If the dimensions change because of shrinkage or swelling, this must be taken into account separately when choosing the input data.
Practical reference points
Units of measurement. For a correct result, thickness and width must be entered in millimeters, length in meters, and quantity in pieces. Mixing units, for example entering length in millimeters instead of meters, causes an error by hundreds or thousands of times.
Common sizes. Common lengths are 2, 3, 4, 5, and 6 m. For boards, common thicknesses are 20, 25, 32, 40, and 50 mm, with widths of 100, 125, 150, and 200 mm, while timber sections often include 50×100, 100×100, 100×150, and 150×150 mm.
Rounding. In practice, sawn timber volume is usually estimated to 0.001 m3, and cost to 0.01 of a currency unit. A small difference between your result and the supplier's documents is often caused only by the rounding method used at different stages.
Relation to European standards
Sawn timber sizes and tolerances. When checking dimensional compliance, common reference documents are EN 1313-1 Sawn timber. Preferred sizes. Softwoods and EN 1313-2 Sawn timber. Preferred sizes. Hardwoods. The calculator itself does not check tolerances automatically, but its calculation logic assumes the use of the product's geometric dimensions.
Structural timber. For structural timber, dimensional requirements and permissible deviations are commonly associated with EN 336 Structural timber. Sizes, permitted deviations. This is important when the cubic volume calculation is used not only for purchasing, but also for comparison with design cross-sections.
Wood moisture content. To determine the moisture content of sawn timber, the standard reference is EN 13183-1 Moisture content of a piece of sawn timber. Determination by oven dry method. This standard does not change the volume formula itself, but it helps explain why actual dimensions and volume may differ between green and dry timber.
FAQs
Why can the supplier's volume differ slightly from my calculation?
In most cases, the reason is different source dimensions and rounding. One supplier may calculate by nominal sizes, while another uses actual sizes after processing, so the cubic volume of sawn timber may differ slightly.
Is this calculator suitable for several board and timber sizes in one batch?
Yes, the sawn timber volume calculation is performed for each item separately, and then the results are summed. This is convenient for mixed orders where the total cubic volume of the whole batch is needed.
Can this calculation be used for planed boards?
Yes, if you enter the actual dimensions after planing. For an accurate result, it is important not to use the nominal size from the product name if the real cross-section has already been reduced by machining.
Why does the calculator not consider wood moisture content and density?
Because this online sawn timber calculation is based on geometric volume rather than weight. Moisture content and density are important for determining timber weight, but they do not change the principle of volume calculation from dimensions.
When is it better to enter nominal sizes and when actual sizes?
For a quick estimate of cost and cubic volume from a price list, nominal sizes are usually used. To check an actually delivered batch, it is better to measure the real board or timber dimensions and perform the calculation using those values.