Pesticide Product Swap Calculator

When two pesticide products share the same active ingredient but differ in concentration (for example, a 2F liquid at 2 lb a.i. per gallon versus a 4F at 4 lb a.i. per gallon), the equivalent rate for the replacement product is a simple ratio:

rate_B = rate_A x strength_A / strength_B

Worked example: product A is a 2F liquid (2 lb a.i./gal) applied at 2 fl oz per 1,000 sq ft. Product B is a 4F liquid (4 lb a.i./gal). The equivalent rate is 2 x (2 / 4) = 1 fl oz per 1,000 sq ft. The stronger product needs half the volume to deliver the same active ingredient per area.

The same formula works for dry formulations when both strengths are stated as percent a.i. by weight (for example, 80 WDG at 80% versus 75 WP at 75%): rate_B = rate_A x 80 / 75. Cross-formulation swaps (liquid to dry or vice versa) are not supported because the strength units are fundamentally different and a simple ratio does not convert between them.

Enter both strengths on the same basis (both a.i. or both a.e.) as printed on each label. Salt and ester forms of the same herbicide may list strength as acid equivalent (a.e.) rather than active ingredient (a.i.); mixing a.i. and a.e. in this calculator gives an incorrect result.

Constants: there are none beyond the label-stated AI strengths you enter. Every figure in this calculator is your input or a direct ratio of your inputs.

Build guard: this calculator is a cross-check. Product B's own EPA label must list your target site and pest. The label rate on product B is the rate you follow. If the calculated equivalent rate exceeds product B's maximum label rate, you must use the lower label rate.

For related conversions, see the active ingredient PPM converter (AI % to ppm, finished %, and oz/gal), the pesticide dilution calculator (concentrate and water for a given ratio and tank), and the chemical cost per 1,000 sq ft calculator (material cost from jug price and spray volume).