Free Lawn & Garden Calculator: Get Seed, Fertilizer & Mulch Amounts Instantly
Use our free lawn calculator to find exactly how much grass seed, fertilizer, and mulch your yard needs. Just draw your lawn and garden beds on the map to get precise amounts in pounds, bags, or cubic yards - based on your exact area, grass type, and goals.
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GenLawn
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Lawn & Garden Calculator
Click on the map to place points
Click point-by-point along your lawn's edges for the most accurate measurement.
More points = more accuracy. Click near your starting point, or press Finish, to complete the shape.
📋 GenLawn — Lawn & Garden Area Report
FAQs about Gen Lawn
Quick answers to help you get the most out of Gen Lawn.
What does this lawn calculator actually do?
It's a free, all-in-one lawn calculator that lets you draw your yard directly on a satellite map instead of typing in length and width. Think of it as a lawn calculator, grass seed calculator, and fertilizer calculator rolled into one: draw your yard once, and get all three estimates instantly.
How do I measure my lawn with this tool?
Search your address or tap "Use My Location" to center the map on your property, then click point-by-point around the edge of your lawn to trace its shape. Click near your starting point (or press Finish) to close it, and your square footage updates instantly in feet, yards, meters, or acres.
How accurate is this lawn size calculator?
The area math itself is highly accurate, using the same geodesic calculation professional mapping tools rely on to convert a drawn shape into real-world square footage. The main variable is how closely you trace your yard's actual edges, so zoom in and add extra points around curves and corners. Also keep in mind satellite imagery can lag a season or two behind, so a recently added pool or bed may not show up until you draw an exclude zone around it yourself.
How much grass seed do I need for a new lawn or overseeding?
It depends on your grass type and whether you're seeding bare soil or thickening an existing lawn, since overseeding rates run roughly half of new-lawn rates. Pick your grass type (Kentucky Bluegrass, Tall Fescue, Bermuda, Zoysia, and others) and either "New Lawn" or "Overseed," and the calculator applies the correct rate to your drawn area automatically.
How much fertilizer per 1,000 sq ft does my lawn need?
Most lawns need about 0.5–1 lb of actual nitrogen per 1,000 sq ft per application. This lawn fertilizer calculator does that conversion for you: enter your fertilizer's N-P-K numbers (or pick a preset) and your target nitrogen rate, and it divides that rate by your fertilizer's nitrogen percentage, then multiplies by your lawn area for the exact pounds of product to buy.
What does N-P-K on my fertilizer bag mean?
N-P-K is the percentage, by weight, of Nitrogen, Phosphorus, and Potassium in the bag. A 16-4-8 fertilizer, for example, is 16% nitrogen, 4% phosphorus, and 8% potassium. Nitrogen is the number that drives most lawn fertilizer math, since it's what growth and green-up rates are based on.
Do I need to calculate mulch beds separately from my lawn?
Yes. Draw them as their own "Mulch Bed" zone rather than including them in your lawn outline. The tool keeps lawn and mulch totals independent, so your seed and fertilizer numbers are based only on actual turf, while your mulch depth calculation (cubic yards, cubic feet, and bags) is based only on your garden beds.
What if my yard has a pool, driveway, or other non-lawn area?
Use the "Exclude Area" tool to trace around anything that isn't grass, such as pools, patios, driveways, and sheds. Excluded areas are automatically subtracted from your total lawn area, so your seed and fertilizer estimates only cover the grass you're actually growing.
Is this lawn calculator really free, and do I need to sign up?
Yes. Every calculator on Gen Lawn, including this one, is 100% free with no email, account, or download required. Draw your yard and get your numbers instantly, no strings attached.
Should I still double-check the numbers before buying seed, fertilizer, or mulch?
It's a good habit for a large order. Use the calculator's estimate as your base, then round up slightly. Most pros suggest a 5–10% buffer for uneven terrain or an imprecise trace, and always check the coverage rate printed on your specific product, since it varies by brand.