Active Ingredient PPM Converter

This is a four-way pesticide concentration converter: AI % ⇄ finished % ⇄ oz/gal ⇄ ppm. Pick the unit you have; the other three are computed. Every ppm figure carries its basis tag — finished solution or active ingredient — because the two differ by the product's AI fraction and confusing them is the most common mix error.

ppm          = finished% × 10,000          (1 ppm = 0.0001%)
finished%    = ppm ÷ 10,000
oz/gal       = (finished% ÷ AI%) × 1.28 × 128   (AI-aware)
finished a.i. ppm = finished% × (AI% ÷ 100) × 10,000
mL/L         = oz/gal × 7.81                (metric concentrate row)

The basis: a finished-solution ppm counts the whole mix; an active-ingredient ppm counts only the a.i. A 0.06% finished mix of a 9.1%-AI product is 600 ppm finished but 54.6 ppm active ingredient (600 × 0.091). ppm and percent are mass ratios, so they read the same in US and metric; only the per-gallon concentrate row switches between fl oz/gal (auto-stepped to tbsp/tsp for small doses) and mL/L.

The "derived" row: the oz-per-100-gallons ↔ ppm anchor (the ~75 factor) is shown only behind a "derived, verify" label. Its named source was unreachable when this tool was built, so it stands on the unit arithmetic alone (28,350 mg in 100 gallons ≈ 75 ppm) and is never presented as a cited conversion. For liquid SC products at 4–10% AI, route ppm through the AI % (the cited legs), not the raw 75 factor.

Per-acre mode (ppm to lb a.i./acre): a ppm is a concentration, not a rate. It becomes a rate only once you say how much spray lands on an acre. Since 1 ppm = 1 mg/L and a US gallon of water weighs 8.345 lb, a ppm read against a gallons-per-acre figure gives pounds of active ingredient per acre directly. Dividing by the product's a.i. fraction turns that into pounds of product per acre.

a.i. ppm     = ppm × (AI% ÷ 100)     (only when the ppm is on the finished basis)
lb a.i./acre = a.i. ppm × gal/acre × 8.345 ÷ 1,000,000
lb product/acre = lb a.i./acre ÷ (AI% ÷ 100)
kg a.i./ha   = lb a.i./acre × 1.1209
L/ha         = gal/acre × 9.354

Worked example: 1,000 ppm of active ingredient in the spray at 100 gal/acre gives 1,000 × 100 × 8.345 ÷ 1,000,000 = 0.8345 lb a.i./acre, which is 0.9354 kg a.i./ha (100 gal/acre is 935.4 L/ha, and 1,000 mg/L × 935.4 L ÷ 1,000,000 gives the same 0.9354 kg). With a 50% a.i. product that is 1.669 lb of product per acre. Switch the output units and the same numbers read in kg/ha and L/ha.

Sources: the 1 ppm = 0.0001% identity and the % × 1.28 rule come from OnlinePestControlCourses; the AI-% percent-solution method from PesticideStewardship. The per-acre constants are unit definitions and a standard applicator figure: 1 ppm = 1 mg/L (parts per million by weight, 1 mg in 1 kg of water); 8.345 lb per US gallon of water at about 60 F; 1 lb/acre = 1.1209 kg/ha and 1 gal/acre = 9.354 L/ha (both from the pound, gallon, acre and hectare definitions). The three are mutually consistent: 9.354 ÷ 8.345 = 1.1209. The 3.785 L/gal and gallon = 128 fl oz figures are common-knowledge unit constants.

This page answers what unit you are in. Two neighbours answer what to pour and how far it goes: the pesticide dilution calculator returns the concentrate and the water for a given ratio and tank size, and the spray coverage calculator turns a per-1,000-square-foot rate into finished gallons and tank loads for a real treatment area. Neither one, and not this converter, tells you whether the product in your hand is a restricted-use pesticide; that classification sits on the label and decides who may buy and apply it.