About LawnMate

LawnMate is a free, browser-based tool that turns your smartphone into a GPS lawn measurement device. Instead of guessing your lawn's size or paying for professional surveying, you can measure it yourself just by walking your yard's perimeter.

How It Works

Using your phone's built-in GPS, LawnMate tracks your position as you walk around the edge of your lawn. The app records each coordinate, calculates the perimeter distance in real time, and uses the shoelace formula to compute the enclosed area. When you return to your starting point, the loop closes automatically and your measurement is ready to save.

There are no accounts to create and no data sent to any server. Your GPS coordinates are processed entirely on your device, and saved measurements are stored in your browser's local storage. You own your data completely.

Built-In Calculators

Knowing your lawn's area is only the first step. LawnMate includes three calculators that turn that measurement into practical answers:

• Fertilizer Calculator — Enter your product's NPK nitrogen percentage and choose a light, standard, or heavy application rate. The calculator tells you exactly how many pounds (or ounces for liquid products) you need for your lawn. No more guesswork, no more over-applying.
• Grass Seed Calculator — Select from eight common grass types and choose between new lawn establishment and overseeding. The calculator uses industry-standard seeding rates to tell you how many pounds of seed to buy.
• Soil Calculator — Planning to add topsoil, compost, or fill dirt? Enter your desired depth and the calculator converts your lawn area into cubic feet, cubic yards, or metric equivalents.

Who LawnMate Is For

LawnMate was built for anyone who takes care of a lawn:

• Homeowners who want to stop wasting money buying too much (or too little) fertilizer, seed, or soil
• DIY lawn care enthusiasts looking for a quick, accurate way to measure irregularly shaped yards
• Landscapers and lawn care professionals who need fast field estimates without expensive survey equipment
• Property managers overseeing multiple lawns and green spaces

Why Accurate Measurement Matters

Applying lawn care products without knowing your lawn's actual size leads to real problems. Over-applying fertilizer wastes money and can burn your grass, leach nitrogen into groundwater, and contribute to algal blooms in nearby waterways. Under-applying means thin, patchy results and wasted effort. The same principle applies to grass seed: too little leaves bare spots, while too much creates overcrowding that weakens the stand.

According to the EPA, excess nitrogen and phosphorus from residential lawn fertilizer is a leading source of nutrient pollution in the United States. Accurate measurement is one of the simplest ways homeowners can reduce their environmental impact while getting better results from their lawn care products.

Free and Private

LawnMate is completely free to use. It works on any GPS-enabled device with a modern web browser — no app store download required. As a Progressive Web App, you can add it to your home screen for quick access. All data stays on your device: we have no servers, no user accounts, and no tracking beyond what is needed to show advertisements that keep the tool free.