Turf: Lawn Care Calculator
Fertilizer, seed & soil math
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
The lawn-care calculator that doesn't sell you fertilizer. Nitrogen, seed, lime, spreader and dilution math — every number cited to a turf-extension source.
Turf is the lawn-care calculator that doesn't sell you fertilizer. Most "lawn apps" are a funnel for one brand's products — Turf is a neutral, citation-backed tool that just does the math: how much nitrogen, how much seed, how much lime, what spreader setting, what dilution. Every number cites a named university turf-extension source. No account, no ads, no subscription, works offline.
NITROGEN RATE (FREE, FOREVER)
Enter your bag's N-P-K analysis, your target nitrogen rate, and your lawn size. Turf returns pounds of product per 1,000 sq ft and for the whole lawn, bags needed, and a slow-release advisory — with a hard guardrail if you exceed the roughly 1.0 lb N per 1,000 sq ft single-application cap (Purdue, Virginia Cooperative Extension). The hero calculator is free forever, at full citation quality.
TURF PRO (ONE-TIME $4.99, NO SUBSCRIPTION)
A single $4.99 purchase unlocks the other five calculators — pay once, keep forever, restore across your devices:
- Spreader calibration — the weigh-back method to dial any spreader to your target rate, because the settings printed on the bag are starting points, not guarantees (Penn State).
- Liquid dilution / tank-mix — convert a product's label rate into ounces per gallon and per 1,000 sq ft, driven by your real, measured sprayer output (US EPA, extension calibration method).
- Lime & sulfur pH amendment — pounds per 1,000 sq ft to raise pH with lime or lower it with elemental sulfur, by soil texture (sand / loam / clay), with per-application caps (Michigan State, Penn State, Clemson HGIC, University of Minnesota, NC State).
- Grass seed rate — pounds of seed per 1,000 sq ft, new seeding vs. overseed, by species: KBG, tall fescue, perennial ryegrass, fine fescue, bermuda, zoysia, centipede (Penn State, Cornell, Texas A&M).
- PGR growing-degree-day timing — accumulate GDD to time your next Primo Maxx / T-Nex (trinexapac-ethyl) application, on the Kreuser & Soldat model.
HONEST BY DESIGN
Turf shows its work and flags what's disputed. The popular "sand 25 / loam 75 / clay 100" lime table isn't in any primary extension publication, so Turf uses the documented turf topdress band instead — and tells you so. The 200-GDD PGR target is validated for golf putting greens, not home lawns, so Turf says that plainly rather than pretending it's universal. For any pesticide or plant-growth regulator, the law is the product label.
SOURCES
Purdue Turfgrass, Virginia Cooperative Extension, Clemson HGIC, Penn State Extension, Michigan State University, University of Minnesota, NC State, Cornell, Texas A&M AgriLife, US EPA, and Kreuser & Soldat (PGR growing-degree-day model).
DISCLAIMER
Turf is an educational reference calculator, not professional agronomic or pesticide-application advice. Always follow the product label and confirm rates with your local cooperative extension office. For any pesticide or plant-growth regulator, the label is the law: it is a violation of federal law to use a product in a manner inconsistent with its labeling (US EPA).
Free download includes the full nitrogen-rate calculator. Turf Pro is a single one-time purchase ($4.99) that unlocks spreader calibration, liquid dilution, lime & sulfur, seed rate, and PGR timing. No subscription, no ads, no account.
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The number keyboard now has a Done button, so you can dismiss it when you're finished. Thanks to everyone who wrote in about this.
The developer, Roman Kopaliani, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
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Information
- Seller
- Roman Kopaliani
- Size
- 578.6 KB
- Category
- Utilities
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later. - iPad
Requires iPadOS 17.0 or later. - Mac
Requires macOS 14.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Turf Pro $4.99
- Copyright
- © 2026 Roman Kopaliani