Slab Pre-Treatment Coverage Calculator

The verified part is the coverage rate. For a horizontal pre-pour barrier the canonical rate is 1 gallon of finished dilution per 10 square feet (0.1 gal/sq ft) on normal/compacted fill. The part most online prose drops is the coarse-fill bump: coarse / gravel fill needs 1.5 gallons per 10 square feet because the product has to penetrate the gravel. This tool foregrounds it as a one-tap toggle:

coverage units  = slab area (sq ft) / 10
finished gallons = coverage units × fill factor
                 = 0.1 × slab area × fill factor
   fill factor   = 1.0  (normal / compacted)
                 = 1.5  (coarse / gravel fill)

concentrate (fl oz) = finished gallons × rate (fl oz / gal)
water (gal)         = finished gallons − concentrate / 128
bottles needed      = ceil(concentrate / bottle size)

Why the fill factor matters: a 4,000 sq ft pad on normal fill needs 400 gal; the same pad on coarse / gravel fill needs 600 gal — the 1.5× bump adds 200 gallons. Get it wrong and you under-buy.

Slab vs trench: this is the horizontal barrier — square feet × a per-10-sq-ft rate. The vertical trench barrier is a different unit basis entirely (linear feet × 4 × trench depth); use the Termite Trench Gallons Calculator for that. Don't conflate the two.

The slab rate (1 gal/10 sq ft) is verified against Pest Control Technology and Virginia Pesticide Safety; the coarse-fill 1.5× factor against Termike. The concentrate dilution figures (0.06% ≈ 0.8 fl oz/gal, 0.09% ≈ 1.2, 0.125% ≈ 1.6) are an illustrative default, not independently confirmed — they ship as an editable rate you override with your product label's figure before mixing. Areas are summed and converted through square meters internally; the gallons math runs in the rate's published imperial units so it reproduces the cited arithmetic exactly.