Agriculture & Forestry
Timber Stand Density Index (SDI) Crown Thinning Sizer
Calculate timber stand density index (sdi) crown thinning using the stated engineering or scientific relationship and adjustable field inputs.
Preparing your result…
What this calculator does
Calculates Timber Stand Density Index (SDI) Crown Thinning Sizer using the formula verified against the cited source.
What your result means
An estimate from the inputs you enter, within the scope stated below — not advice.
Formula
SDI = TPA × (QMD ÷ 10)^1.605
The step-by-step working for your own numbers appears with the result above and in the PDF report.
Frequently asked questions
Symbols and assumptions
- Inputs
- The values entered in the fields above
- • Reineke SDI (English convention)=trees per acre×(quadratic mean DBH inches/10)^1.605.
Sources and review
Reviewed 2026-10-18 · Next review 2027-04-18
- • QMD=sqrt(mean(DBH²)), not arithmetic mean diameter. Original index describes equivalent density at10-inch QMD, especially even-aged stands. Thinning/crown recommendations additionally need species/site-specific maximum SDI and management objectives; do not apply one universal threshold or metric input without conversion.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Quick reference
| Scenario | Trees per acre | Quadratic mean diameter (in) | Stand density index |
|---|---|---|---|
| Worked example | 300 | 9 | 253.3264 |
| Half the amounts | 150 | 4.5 | 41.6387 |
| Double the amounts | 600 | 18 | 1,541.2164 |
Need the full picture? Get the detailed PDF report with charts, tables, formulas and working steps.
Reviewed 2026-10-18 · Next review 2027-04-18
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