Forest Basal Area Calculator
Use quadratic mean diameter (QMD), or matching diameter classes and stem counts, with the sampled area to calculate basal area.
A QUICK WALKTHROUGH
How to use this tool
- Choose QMD or DBH classes and enter diameters in cm with the matching stem counts.
- Enter the sampled area in hectares and calculate.
- Review total basal area and stand basal area per hectare or acre; copy or download the results if needed.
Method and scope
Basal area per tree is π × (DBH ÷ 2)². In QMD mode, multiply that area by the entered stem count. In DBH-class mode, calculate and sum the area for each diameter and count pair. Divide total tree area by sampled area to get stand basal area. This is a stand-structure measure, not a yield, harvest, or management forecast.
Diameter and area units
Enter diameters in centimetres and sampled area in hectares. The calculator reports total basal area in m² and area-normalized stand basal area in m²/ha and m²/acre. In DBH-class mode, enter matching diameter and count lists separated by commas or new lines. Arithmetic mean DBH is not quadratic mean diameter.
Source and local processing
USDA Forest Service basal area definition: https://apps.fs.usda.gov/fsgisx02/rest/services/r05/r05_SNV_ACCEL_01/MapServer/37. Inputs remain in this browser; results are estimates from values you supply.
GOOD TO KNOW
Common questions
What is basal area?
It is the cross-sectional area of a tree stem at breast height; stand basal area sums tree areas and can be divided by sampled area.
Can I use arithmetic mean DBH as QMD?
No. Enter a true quadratic mean diameter, or use the DBH-class mode with the diameter classes and counts.
Does this recommend equipment or management actions?
No. It reports calculations from your inputs and does not estimate yield or recommend actions.