About
LawnToolbox exists because the arithmetic of lawn care is settled and almost nobody presents it that way. Extension offices published the rates decades ago. What's been missing is a set of tools that apply them to your square footage, show their working, and tell you the truth even when the truth is "you don't need to buy anything."
Ask the internet how much fertilizer to put on your lawn and you'll get three kinds of unhelpful answer. The bag says "covers 5,000 sq ft," which tells you nothing about how much nitrogen that is. The month-by-month calendars say "fertilize in September," with no quantity and no adjustment for whether you're in Minnesota or Georgia. And the genuinely good math — pounds of nitrogen per 1,000 square feet, seeding rates by species, frost-shifted timing — is scattered across extension PDFs that nobody reads at the garden center.
Meanwhile none of it is secret. It just needs implementing with some care, attaching to the one number that makes it personal — your lawn area — and explaining without an upsell attached.
I'm Brian Hamilton, and I build and maintain every calculator, guide and line of arithmetic on LawnToolbox. The site is published by Hamilton Digital Media Limited, my company — the same one behind a wider collection of calculators and tools, alongside puzzle games, apps and books. Company details are in the footer of every page and in the terms; there is a real, registered business behind this site, which is not something most lawn-advice pages can say.
I'm not a turf scientist or a landscaper, and I'm not going to pretend to be one. I build calculation tools for a living — that's the work, and this site is that work pointed at lawns, gardens and grow tents.
I think that's the right qualification for this particular job, and here's the honest reasoning: most of lawn care is a math problem wearing muddy boots. The rates are published. What goes wrong in practice isn't the agronomy — it's square footage that was guessed, bags that were never converted to pounds of nitrogen, and advice shaped by what the person giving it happens to sell. Those are engineering and integrity problems, and they're the ones I can actually fix.
Where genuine domain expertise is required, I lean on the people who have it and say so by name — the extension publications cited on each page. And where I'm uncertain, the site says it's uncertain rather than rounding up to confidence: the planner tells you when its dates are a template, the lime estimate tells you a soil test replaces it.
Not "trust us" — here's the mechanism, and you can check every part of it yourself.
Seeding rates, nitrogen math, frost-date conventions and the seasonal calendar come from university extension publications and standard agronomic formulas — each table names its source, rather than copying another site's numbers where an error would propagate silently.
Every calculator and the planner call the same calculation modules. Two tools on this site physically cannot give you different answers for the same lawn, because there is only one implementation of each formula.
The engine is covered by an automated test suite that runs on every change, cross-checked against hand-worked and published reference values. If a change would alter a known-good result, the build fails before it reaches you.
Every result has a "show the math" panel with the actual arithmetic, in your units. You should never have to take a number on trust — and if the reasoning looks wrong, you can see exactly where.
The agronomy here isn't ours and we don't claim it. Seeding rates, mowing heights and nitrogen schedules come from university extension guides — Penn State, Maryland and Purdue for cool-season turf; Clemson, Georgia and Texas A&M for warm-season — and from the fertilizer-rate fact sheets published by UNH and Rutgers. Frost dates by zone are the common almanac conventions, offered as defaults you can override with your own. Irrigation and hydroponic math follows the standard published relationships, cited where used.
Our contribution is the implementation, the testing, the planner that ties it to your zone and area, and the writing — plus a stubborn insistence on showing the arithmetic so you're never asked to take a number on faith.
A site whose entire promise is "the numbers are right" has to mean it, which means being easy to correct. If you find a mistake — in a calculation, a rate, a date, a recommendation, or a fact in an article — [email protected] goes straight to a person. We'll fix it quickly and note on the page what changed and when. No defensiveness, no quiet edits.
That's not politeness. Regions differ, products get reformulated, and state fertilizer rules change. A correction channel that people actually use is the cheapest quality control there is.
Some links to products earn a commission at no cost to you. That's the whole model — no ads that follow you around, no paid reviews, no sponsored placements, and nothing gated behind a signup (the printable plans and calendar files are free and ask for no email). The rules we hold ourselves to are written down in the affiliate disclosure, and the important one is this: the math picks the recommendation, and we say so when the cheapest option is the right one. Plenty of the best answers in lawn care — plain urea, a soil test before lime, a tuna can to measure your sprinklers — earn us almost nothing. We publish them anyway, because a site that recommends whatever pays best gets read once.
LawnToolbox is new. The Lawn Care Planner is the centerpiece — grass type, area and zone in, a dated year out — and the first calculators it draws on are live: lawn area, lawn fertilizer, grass seed, sod, lime application, topdressing sand, sprayer & tank mix, spreader calibration, pre-emergent timing, mulch, topsoil, raised bed soil, soil blend, plant spacing, seed starting dates, gravel & paver base, sprinkler precipitation rate, watering run time, drip irrigation, zone gpm & pipe sizing, rainwater harvesting, irrigation water cost, vpd, dli, grow light coverage, ec ↔ ppm, nutrient dosing, reservoir top-off, robot mower savings and lawn care annual cost. The rest of the toolbox — garden beds and mulch, irrigation, indoor growing, cost calculators — is being added in the order people need them, with the guides that explain the why behind each number following close behind.
Your yard's details are remembered in your own browser so you don't retype them every visit — and they never reach us, which is the sort of thing that's easy to promise and easy to verify: it's covered in the privacy policy, and there's a button there that deletes the lot.