> ## Documentation Index
> Fetch the complete documentation index at: https://pyfia.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Volume

> Net merchantable bole volume by diameter class, EVALIDator-validated.

Volume queries expand `TPA_UNADJ × VOLCFNET` with diameter-based adjustment factors, restricted to merchantable timber species (≥5" DBH, non-woodland) on timberland.

## California — net merchantable volume by diameter class

<Info>**EVALID:** 62101 (California 2021) · **Result:** 67.05 billion cubic feet (4,188.7 cu ft/acre) · [source](https://github.com/mihiarc/pyfia/blob/main/reference/queries/volume/california_volume_by_diameter.sql)</Info>

<Accordion title="View SQL">
  ```sql theme={null}
  SELECT
      CASE
          WHEN tree.dia <= 6.99 THEN '5.0-6.9'
          WHEN tree.dia <= 8.99 THEN '7.0-8.9'
          WHEN tree.dia <= 10.99 THEN '9.0-10.9'
          WHEN tree.dia <= 12.99 THEN '11.0-12.9'
          WHEN tree.dia <= 14.99 THEN '13.0-14.9'
          WHEN tree.dia <= 16.99 THEN '15.0-16.9'
          WHEN tree.dia <= 18.99 THEN '17.0-18.9'
          WHEN tree.dia <= 20.99 THEN '19.0-20.9'
          WHEN tree.dia <= 28.99 THEN '21.0-28.9'
          ELSE '29.0+'
      END AS diameter_class,
      SUM(
          TREE.TPA_UNADJ * TREE.VOLCFNET *
          CASE
              WHEN TREE.DIA < 5.0 THEN POP_STRATUM.ADJ_FACTOR_MICR
              WHEN TREE.DIA < COALESCE(CAST(PLOT.MACRO_BREAKPOINT_DIA AS DOUBLE), 9999.0) THEN POP_STRATUM.ADJ_FACTOR_SUBP
              ELSE POP_STRATUM.ADJ_FACTOR_MACR
          END * POP_STRATUM.EXPNS
      ) AS total_volume_cuft
  FROM POP_STRATUM
  JOIN POP_PLOT_STRATUM_ASSGN ON (POP_PLOT_STRATUM_ASSGN.STRATUM_CN = POP_STRATUM.CN)
  JOIN PLOT ON (POP_PLOT_STRATUM_ASSGN.PLT_CN = PLOT.CN)
  JOIN COND ON (COND.PLT_CN = PLOT.CN)
  JOIN TREE ON (TREE.PLT_CN = COND.PLT_CN AND TREE.CONDID = COND.CONDID)
  JOIN REF_SPECIES ON (TREE.SPCD = REF_SPECIES.SPCD)
  WHERE
      TREE.STATUSCD = 1                       -- Live trees
      AND COND.RESERVCD = 0                   -- Unreserved
      AND COND.SITECLCD IN (1, 2, 3, 4, 5, 6) -- Timberland site classes
      AND COND.COND_STATUS_CD = 1             -- Forest conditions
      AND TREE.VOLCFNET IS NOT NULL
      AND TREE.DIA >= 5.0                     -- Merchantable timber
      AND REF_SPECIES.WOODLAND = 'N'          -- Timber species
      AND pop_stratum.rscd = 26               -- California
      AND pop_stratum.evalid = 62101
  GROUP BY diameter_class
  ORDER BY MIN(tree.dia);
  ```
</Accordion>

<Tip>The Python equivalent is [`volume()`](/api/pyfia-estimation-estimators-volume) with `by_size_class=True`.</Tip>