The calibrated output is derived from what your sprayer actually delivered to a measured test area — not assumed from a label. Both field methods land on the same ounces-per-1,000-sq-ft backbone.

Catch-ounces:   oz/1,000 sq ft = oz collected × (1,000 / test area)
Tank-difference: oz used = before − after → same oz/1,000 sq ft

gal/1,000 sq ft = oz/1,000 ÷ 128        (128 fl oz per US gallon)
gal/acre        = gal/1,000 × 43.56      (43,560 sq ft per acre)

Mix plan (when supplied):
  coverage units    = full area / 1,000
  total carrier gal = coverage units × gal/1,000
  tank loads        = ceil(total carrier / tank capacity)
  total concentrate = coverage units × label rate
  concentrate/tank  = label rate × (tank capacity / gal/1,000)

Pass/fail (vs intended carrier rate):
  % error = (measured − target) / target × 100
  PASS if |% error| ≤ 5, otherwise ADJUST (sign drives the direction)

The canonical shortcut: a 1,000 sq ft plot is 20 ft × 50 ft, so the ounces you collect are your output in ounces per 1,000 sq ft. Arbitrary plot sizes work too — the oz × 1,000 / area step normalises any area to a per-1,000 rate.

The ±5% tolerance is the extension acceptance rule: if the measured rate is off by more than 5% of the intended rate, adjust your walking speed (most practical) or pressure and re-measure. Measured high → slow down or lower pressure; measured low → speed up or raise pressure.

Sources: Pesticide Environmental Stewardship — backpack sprayer calibration (the 57 oz / 1,000 sq ft worked example, 148 oz ≈ 1.1 gal carrier, 5.2 oz product); Ohio State University Extension FABE-531 — tank-difference and timed-catch methods, the × 43,560 acre conversion, and the verbatim ±5% acceptance rule.