Pick your state to see its cited lime source. Where the exact method is live, enter your soil-test values and get a rate computed from your state's land-grant extension publication — not a national average. Staged methods are marked before any inputs. Six live calculators today: Penn State Mehlich Buffer acidity, UGA Ca(OH)2 titration → LBCEq, UVM reactive aluminum, MSU's 1.5×ΔpH wheat rule, and the UC ANR / Texas A&M pH×texture tables. Honest "lime rarely needed" advisory for all six alkaline-soil states (Arizona, Colorado, Nevada, New Mexico, Utah, Wyoming) — no automatic zero rate. Pending methods stay labeled pending; they are never sold as live lab-specific math.
Pick your state and enter your soil-test values. We'll show the lime rate per acre, the math, and your state's source citation.
Lime rate is driven by your soil's reserve acidity, not its measured pH alone. The lab measures reserve acidity several ways depending on your state's extension method — exchangeable acidity, a buffer-pH reading, reactive aluminum, a Ca(OH)₂ titration, even pH × soil texture. Zone Forge maps every state to published guidance and labels each method as live or pending. When the mapped method is live, this calculator auto-selects it; pending methods stay visible but cannot be submitted. Two live examples show how different the methods can be:
Penn State (Mehlich Buffer / Exchangeable Acidity) — the method Penn State publishes today. Penn State retired the older Adams-Evans buffer-pH method a few years back; the AASL lime recommendation is now driven by the Mehlich Buffer test, reported on the soil-test report as "Acidity" in meq/100 g. We look up your acidity in the published table at the pH-goal column matching your crop, then convert lb CCE/ac to tons.
UGA Ca(OH)2 titration → LBCEq — Georgia's Circular 874 path: lab LBC30 converts to equilibrium LBCEq, then to a rate for the crop's published target pH. Different lab report, different inputs — not a buffer-pH crosswalk.
Other live methods — Vermont reactive aluminum (UVM Table 3), Montana's 1.5×ΔpH wheat rule with incorporation guidance, and California / Texas pH×texture tables for their published crop scopes. Pending midwest buffer-pH sources (for example Iowa PM 1688 and Tri-State) stay labeled coming soon until their exact tables ship.
On every live method we divide by your product's ECCE rating to get the actual tons of physical product per acre. Most online lime calculators skip ECCE. That matters: a 70% ECCE product needs ~43% more tons-per-acre than a 100% ECCE pelletized lime to deliver the same neutralizing capacity. Get this wrong and you'll over- or under-apply by a third.
This page runs Zone Forge's production lime engine for a single point — the same math the in-app lime panel and chat tool use when a method is live. Variable-rate field zoning and equipment delivery are separate product work; this free tool does not generate a lime shapefile or push an in-cab prescription. Sign up for field tools and soil maps without assuming lime Rx delivery is already built.
This free calculator answers one point with a cited rate. Inside the app you can upload soil tests, map fields, and use Zone Forge's field tools — without a claim that lime variable-rate shapefiles or John Deere in-cab lime prescriptions are delivered today. When those lime Rx surfaces ship, they will use the same live methods and citations shown here.
Lime is just the start. Upload your full soil test and Zone Forge grades every nutrient in your own state university's rating words for 26 states — and for the rest, honestly shows the measured value with a note on why we don't grade that lab format yet. Worst-first, color-coded, with your fertility trend across past tests.
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