Grass seed calculator
A 5,000-square-foot lawn seeded at 5 pounds per 1,000 square feet needs 25 pounds of seed. Turn the rate on the bag into seed per square foot, multiply by your measured area, and buy for a new lawn, an overseed or a patch. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Area
- 5,000
- Interest rate
- 0.005
- Seed amount
- 25
- Unit area
- area_unit
- Unit rate
- seed_per_area
- Unit seed
- seed
This grass seed calculator multiplies lawn area by a seeding rate per unit area to tell you how much seed to buy for a new lawn, an overseed, or a patch repair. Homeowners and landscapers often mis-scale bag labels when the label quotes pounds per thousand square feet while the yard was measured in total square feet, or when a metric rate in grams per square metre is applied to a plan drawn in feet. The response is fully deterministic with no network calls, no sampling, and no date-dependent shortcuts.
What the calculator returns and how seed amount is defined
Grass seed amount here is the product of the measured lawn surface and the manufacturer or agronomic seeding rate expressed per unit of that same surface. Seed bags and professional specs almost always quote a rate such as pounds per thousand square feet, kilograms per hectare, or grams per square metre; this tool expects you to convert that published rate into seed per one unit of area so multiplication stays linear and transparent.
For example, five pounds per thousand square feet becomes zero point zero zero five pounds per square foot, then multiplies by five thousand square feet to yield twenty-five pounds of seed. Treat the result as a planning estimate and round up slightly for edges, bare spots, or the extra seed many bag labels recommend for new establishment versus overseeding.
Where grass seed estimates fit for DIY, quotes, and software
DIY gardeners meet this problem when a spring overseed needs a lighter rate than a bare-soil new lawn, when a rectangular backyard is measured in feet but the bag aisle quotes seed per thousand square feet, or when a small patch repair must not open a full commercial bag without knowing the true need.
Trade estimators use the same identity across dozens of lots: measure plan area, pick the rate from the seed label or the job specification, convert rate to per-unit-area form if needed, and multiply for total seed before ordering pallets or retail bags. Teachers and vocational trainers can pre-generate answer keys for modest lawn sizes without trusting opaque mobile apps that switch units mid-form or forget that a thousand-square-foot rate must be scaled to the whole yard.
Developers call the same contract from scripts to seed deterministic test vectors for landscape calculators, to normalise user-entered lawn sizes before a cart suggests bag counts, or to satisfy programming-challenge statements that demand seed mass rather than a hand-waved “about two bags.” Product tools use the multiply when a homeowner types five thousand square feet and a converted rate and the UI must show total seed before checkout.
What you can do with it
Contractor multi-lot quotes
Feed measured lot areas and specified seeding rates from the plant schedule to produce reproducible seed totals for bids.
FAQ
What does the grass seed calculator cost?
It is free in your browser on this page.
How is seed amount calculated?
Use matching units (for example square feet with pounds per square foot, or square metres with grams per square metre).
What if I enter zero or negative area or rate?
Both area and rate must be strictly positive numbers greater than zero.
Does the tool convert between square feet and square metres?
No. You supply a consistent area unit and a matching per-area rate; the calculator only multiplies them.
Do I use the same rate for overseeding and a new lawn?
No. A spring overseed usually calls for a lighter rate than seeding bare soil, and many bag labels recommend extra seed for a new lawn. Take the rate for your job from the label or the job specification.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/home/grass-seed \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"area":5000,"rate":0.005}'const res = await fetch("https://api.kit.forhosting.com/home/grass-seed", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"area": 5000,
"rate": 0.005
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/home/grass-seed",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"area": 5000,
"rate": 0.005
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/home/grass-seed", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"area":5000,"rate":0.005}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"area":5000,"rate":0.005}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/home/grass-seed", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"area": 5000,
"rate": 0.005
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "home.grass_seed",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
max_abs | 1000000000 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
The engine accepts any consistent pair of units: if area is in square feet and rate is in pounds per square foot, seed_amount is in pounds; if area is in square metres and rate is in grams per square metre, seed_amount is in grams. The identity is simply seed_amount equals area times rate, with strict rejection of zero or negative area and rate so a blank form field cannot claim free seed.
What the calculator returns and how seed amount is defined
The JSON response echoes area, rate, seed_amount rounded to the requested precision, unit tags that mark area, rate, and seed as abstract consistent units, the method tag area_times_seeding_rate, and a short formula string. There is no grass-species database, no climate zone lookup, no germination percentage adjustment, and no shopping cart: the page answers only the mass or volume of seed implied by area times rate with stable numbers suitable for worksheets, contractor quotes, and API consumers that must match goldens run after run.
How inputs are read, validated, and kept reproducible
Preferred fields are area for lawn surface in your chosen area unit and rate for seed amount per unit of that area, plus optional precision for display rounding. Aliases such as lawn_area, sqft, and square_feet for area, and seeding_rate, seed_rate, and rate_per_area for rate are accepted so spreadsheets, query strings, and typed forms can reuse the same contract without renaming columns. Every numeric field must be finite; non-positive area or rate is rejected with invalid_input so a zero-area form field cannot silently claim free seed and a negative rate cannot invert the physics of planting. An optional precision field, with aliases decimals and dp, chooses how many decimal places to expose for area, rate, and seed_amount, defaulting to four and capped at fifteen so JSON goldens stay stable across engines. Pair the free browser run on this page with the priced API when you need the identical mathematical result inside an automated pipeline without re-implementing the grass seed formula yourself.
Where grass seed estimates fit for DIY, quotes, and software
On this page the work runs entirely in your browser; through the API each successful lookup costs $0.002, failed validation is not charged, and nothing is stored after the response returns. That split — free interactive exploration and a priced, identical API — matches the rest of the KIT tier-A catalog and lets you move from a backyard demo to an automated quoting pipeline without changing the mathematical result. Pair it with unit converters when your tape measure and bag label disagree on systems of units, and with other home or geometry endpoints when you are building a small lab of free, deterministic planning helpers for outdoor projects.
Integration use cases
New lawn or overseed shopping list
Convert the bag’s lb-per-1000-sq-ft rate to per-square-foot form, enter total lawn area, and buy the exact seed_amount you need.
Deterministic fixtures for apps
Generate stable seed_amount values for unit tests in landscape planners, e-commerce bag suggesters, and CI checks.
Technical questions
My bag says 5 lb per 1,000 sq ft — what rate do I enter?
Convert to seed per one square foot: 5 / 1000 = 0.005, then pass rate=0.005 with area in square feet. seed_amount will be in pounds.