Tree Diameter (DBH) Calculator
Turn trunk circumference into diameter at breast height in inches, centimetres and feet, plus basal area, Doyle log scale and a size class.
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Stand Basal Area and Stocking Calculator
Work out the basal area of a woodlot from tree count and diameter, compare it with the target for your cover type and size the cut.
Stand Basal Area and Stocking Calculator
Chlorova · updated for 2026
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Click “Calculate” to see your results.
Target basal area figures are the commonly published full stocking guides for the northeast and lake states, and they vary by region, site index, ownership objective and edition of the guide, so check the table published for your state. Basal area is measured with a wedge prism or meter at breast height of 4.5 ft, and an average diameter hides a wide distribution that changes which trees should actually be cut. Doyle scale understates volume in large diameter logs, so a timber cruise by a consulting forester is the right step before a sale is marked or advertised.
Stocking is the one woodlot number that tells you whether to cut, and it takes two measurements. Basal area is the total cross sectional area of all the stems on an acre, expressed in square feet, and comparing it with the published target for your cover type says whether the crowns are closed, comfortable or wasting room. This calculator does the arithmetic from tree count and average diameter, converts the difference into stems to remove, and reports Doyle scale alongside, which is what a logger will price.
Measuring a Stand and Reading the Answer
- Choose the cover type that sets the target.
- Count stems per acre at sawline or larger.
- Enter the average diameter at breast height.
- Give the total area of the stand in acres.
- Set merchantable log length for your region.
- Read stocking percent before the volume lines.
- Use stems to remove as your marking budget.
- Compare the spacing figure with what you walk.
- Check both verdict bands before marking anything.
- Try a second cover type to see targets shift.
- Note basal deficit if the stand is thin rather than full.
- Cruise the timber before advertising a sale.
Basal Area, Stocking and Stems to Remove
Basal area of one tree is 0.005454 times diameter squared, which is the cross sectional area of the stem at breast height in square feet. Multiply by stems per acre and you have stand basal area, the density measure that stocking guides are written against, so sixty maples at 16 in give 1.40 sq ft each and 83.8 sq ft an acre.
Stocking percent is that figure over the target for the cover type, here 129 percent of 65 sq ft. The surplus is then converted back into trees by dividing the excess basal area by the basal area of one average stem, which is how a thinning budget in square feet becomes a count of stems to mark. Stem spacing is the square root of acre area over stem count, a sanity check on what the density really looks like on foot.
Worked Example: 60 Maples an Acre at 16 Inches
- Choose northern hardwoods, target 65 sq ft per acre.
- Sixty stems an acre at 16 in average diameter.
- Each tree holds 1.40 sq ft of basal area.
- The stand therefore carries 83.8 sq ft an acre.
- That is 129 percent of the target stocking.
- Surplus is 18.8 sq ft an acre to take out.
- Divide it by 1.40 and mark 13 stems an acre.
- Stems are about 26.9 ft apart on average.
- Across 5 acres that is 300 stems and 419 sq ft.
- Doyle scale is 144 bf per tree, 8,640 an acre.
- The whole stand therefore carries 43,200 bf.
- A wedge prism cruise would confirm or correct this.
Full Stocking Targets by Cover Type
Basal area in square feet per acre that regional stocking guides treat as fully stocked for sawtimber, which is the number the verdict band reads against.
| Cover type | Target sq ft | Stems at 16 in | Notes |
|---|---|---|---|
| Northern hardwoods | 65 | 47 | Self thins if left |
| Mixed oak | 75 | 54 | Cut on a seed year |
| Black walnut | 70 | 50 | Crop tree management |
| Loblolly pine | 85 | 62 | Thinned on a cycle |
| Red or white pine | 90 | 66 | First thinning runs late |
| Aspen and birch | 80 | 59 | Even aged, short rotation |
Key Terms
- Basal area
- Total cross sectional area of stems, in square feet per acre.
- Stocking
- How close basal area sits to the published target for a cover type.
- Sawline
- The smallest stem a logger will saw, usually 8 to 10 in diameter.
- Wedge prism
- A hand gauge that counts trees as a basal area sample.
- Thinning
- Removing stems to release the ones you want to grow on.
- Doyle scale
- A board foot rule that suits small and medium eastern hardwoods.
How Foresters Use These Numbers
- A stocking percentage tells you when to act, but the diameter distribution tells you what to cut, and an average of 16 in can hide either a even stand or a few big stems over many thin ones.
- Landmark and DoNothing style gauges for hardwoods were built to keep landowners out of trouble, and both lean toward leaving more basal area than a mature stand can grow on.
- The most common mistake on a small woodlot is cutting to a basal area target with no marking rule, then losing the best trees because they were the easiest to identify.
- Pine plantations respond predictably to thinning, which is why the target is higher and the cycle is scheduled, while a mixed hardwood stand is managed toward a future crop rather than a volume number.
- Volume rules disagree deliberately, since Doyle understates large logs, so two buyers quoting a tract on different scales are not cheating each other.
Common Mistakes & Fixes
- Measuring diameter at 3 ft instead of 4.5 ft.
- Using a stocking target from another region entirely.
- Counting seedlings in a sawtimber stem tally.
- Averaging diameter across every species in the stand.
- Cutting the biggest trees because they are obvious.
- Thinning a fully stocked oak stand in a poor acorn year.
- Ignoring access, which decides what can actually be pulled.
- Selling by estimated volume with no written contract.
- Leaving no buffer along a stream, road or property line.
- Judging a whole stand by one casual walk through it.
When to Reach for This
Use it before hiring a forester so you can follow the conversation, when deciding whether a stand is ready for a thinning, when comparing two woodlots for purchase, and when writing a forest stewardship plan. Pair it with the tree diameter calculator to get honest DBH from a tape measure, the timber value calculator to price what you would cut, the planting spacing planner for what to leave room for, and the feed a family planner if the woodlot is heating fuel.
Stand Basal Area and Stocking Calculator: Frequently Asked Questions
What is basal area and why use it instead of tree count?
It is the total cross sectional area of the stems on an acre, in square feet, which accounts for both how many trees you have and how big they are. A count of 60 stems tells you almost nothing on its own, while 84 sq ft of basal area says the crowns are closed and growth is slowing.
How do I measure basal area without a forester?
Either count stems and average diameter and let this calculator do it, or use a wedge prism or angle count gauge, which is quick and cheaper than a cruise. The gauge version counts only trees that appear offset through the wedge, and each count equals a fixed square feet of basal area.
What stocking percentage means it is time to thin?
Around one hundred to one hundred twenty percent of full stocking is the usual trigger for a thinning that will pay, since the stand is using all its site and additional growth is slowing. Below about seventy percent you are usually early, and the money is better spent on release cutting.
Why is the target for pine so much higher than hardwoods?
Because plantations are single species, even aged and bred for straight growth, so they hold more area per acre before crowns shut down height growth. A northern hardwood stand at that density would be losing trees to self thinning rather than putting on sawlog volume.
Does the calculator tell me which trees to mark?
No, and that is the part a person has to do. It gives a budget in square feet and stems, and marking then follows crop tree rules, which favor well spaced trees with live crown, straight stems and the species you want standing in twenty years.
How accurate is the Doyle volume figure?
It is a rule of thumb priced from diameter and log length, and it is known to understate volume on large diameter logs while being reasonably fair on medium eastern hardwoods. Log buyers use it, so the number here is useful for a conversation, but it is not a cruise.
Sources & Further Reading
- Forest Management: Release, Thinning and Intermediate Cuttings — Penn State Extension. Basal area targets and thinning triggers for eastern stands.
- A Field Guide to the Identification and Management of Northern Hardwood Stands — University of Maine Cooperative Extension. Stocking guides and marking rules for hardwoods.
- Thinning Pine Stands — Auburn University Extension. Pine stocking levels, thinning cycles and expected response.
- Timber Volume and Scaling Rules Compared — USDA Forest Service, Southern Research Station. Doyle, Scribner and International scales and their bias.
Chlorova Gardening Team
Builds, checks and documents every tool we publish
Chlorova editorial review
Checked against extension-service publications
Formula verified against published references · Updated
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