{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"lawn-seed-fertilizer"},"result":{"entity_type":"calculator","id":"lawn-seed-fertilizer","calculator_id":"lawn-seed-fertilizer","canonical_url":"https://tttkmbb.com/everyday/lawn-seed-fertilizer","name":"Lawn Seed and Fertilizer Calculator","title":"Lawn Seed and Fertilizer Calculator – Pounds of Grass Seed and Fertilizer for a Lawn Area","category":"everyday","category_name":"Everyday Life","tool_name":"estimate_lawn_seed_and_fertilizer","featured_mcp_tool":false,"description":"Computes the grass seed needed for a new lawn or overseeding from the area and the species' seeding rate (Penn State and UF/IFAS extension rates in lb per 1,000 ft²), and the fertilizer needed to apply a target amount of nitrogen from the N percentage on the bag.","use_when":"You are seeding or overseeding a lawn of known size and need to know how many pounds or kilograms of seed and of a given N-P-K fertilizer to buy.","do_not_use_when":"You are laying sod or turf rolls, need a soil-test-based lime or phosphorus recommendation, or want spacing for individual plants (use plant-spacing).","inputs":[{"name":"area","label":"Lawn area","type":"number","required":true,"max":10000000,"exclusive_min":0,"description":"Area to seed, in the chosen unit.","example":5000},{"name":"area_unit","label":"Area unit","type":"enum","required":false,"default":"ft2","values":[{"value":"ft2","label":"Square feet","aliases":["sqft","sq_ft","square_feet","ft²"]},{"value":"m2","label":"Square metres","aliases":["sqm","sq_m","square_meters","square_metres","m²"]}],"description":"Unit of area.","example":"ft2"},{"name":"grass_type","label":"Grass type","type":"enum","required":true,"values":[{"value":"kentucky_bluegrass","label":"Kentucky bluegrass – 2.5 lb/1000 ft² (Penn State 2–3)","aliases":["bluegrass","kbg"]},{"value":"tall_fescue","label":"Turf-type tall fescue – 7 lb/1000 ft² (Penn State 6–8)","aliases":["fescue","ttf"]},{"value":"perennial_ryegrass","label":"Perennial ryegrass – 5 lb/1000 ft² (Penn State 4–5)","aliases":["ryegrass","rye"]},{"value":"fine_fescue","label":"Fine fescues – 4.5 lb/1000 ft² (Penn State 4–5)","aliases":["creeping_red_fescue","chewings_fescue"]},{"value":"mix_cool_season","label":"Bluegrass / fine fescue / ryegrass mixture – 3.5 lb/1000 ft² (Penn State 3–4)","aliases":["mix","mixture","cool_season_mix","sun_and_shade"]},{"value":"bermuda","label":"Bermudagrass, hulled seed – 2 lb/1000 ft² (UF/IFAS 1–4)","aliases":["bermudagrass"]},{"value":"bahia","label":"Bahiagrass – 8 lb/1000 ft² (UF/IFAS 5–10)","aliases":["bahiagrass"]},{"value":"centipede","label":"Centipedegrass – 0.5 lb/1000 ft² (UF/IFAS 0.25–1)","aliases":["centipedegrass"]}],"description":"Grass species or mixture; sets the seeding rate for a new lawn.","example":"tall_fescue"},{"name":"seeding","label":"Seeding","type":"enum","required":false,"default":"new_lawn","values":[{"value":"new_lawn","label":"New lawn (full rate)","aliases":["new","establishment","bare_soil"]},{"value":"overseed","label":"Overseeding an existing lawn (half rate)","aliases":["overseeding","renovation"]}],"description":"New lawn on bare soil, or overseeding into existing grass at half the rate.","example":"new_lawn"},{"name":"fertilizer_n_percent","label":"Fertilizer nitrogen","type":"number","unit":"%","required":false,"default":24,"max":100,"exclusive_min":0,"description":"First number of the N-P-K analysis on the bag (24 for a 24-0-4 fertilizer).","example":24},{"name":"target_n_lb_per_1000ft2","label":"Target nitrogen","type":"number","unit":"lb N/1000 ft²","required":false,"default":1,"max":3,"exclusive_min":0,"description":"Nitrogen to apply per 1,000 ft² in this application; starter applications use 0.5–1 lb.","example":1}],"outputs":[{"name":"area_ft2","label":"Area","type":"number","unit":"ft²","decimals":0,"description":"Lawn area in square feet."},{"name":"area_m2","label":"Area","type":"number","unit":"m²","decimals":1,"description":"Lawn area in square metres."},{"name":"seed_rate_lb_per_1000ft2","label":"Seeding rate","type":"number","unit":"lb/1000 ft²","decimals":2,"description":"Rate applied (half the new-lawn rate for overseeding)."},{"name":"seed_rate_g_per_m2","label":"Seeding rate","type":"number","unit":"g/m²","decimals":1,"description":"Same rate in grams per square metre."},{"name":"seed_lb","label":"Seed","type":"number","unit":"lb","decimals":1,"description":"seed_rate × area_ft2 / 1000."},{"name":"seed_kg","label":"Seed","type":"number","unit":"kg","decimals":2,"description":"Seed in kilograms."},{"name":"fertilizer_rate_lb_per_1000ft2","label":"Fertilizer rate","type":"number","unit":"lb/1000 ft²","decimals":2,"description":"target_n × 100 / fertilizer_n_percent."},{"name":"fertilizer_rate_g_per_m2","label":"Fertilizer rate","type":"number","unit":"g/m²","decimals":1,"description":"Same rate in grams per square metre."},{"name":"fertilizer_lb","label":"Fertilizer","type":"number","unit":"lb","decimals":1,"description":"fertilizer_rate × area_ft2 / 1000."},{"name":"fertilizer_kg","label":"Fertilizer","type":"number","unit":"kg","decimals":2,"description":"Fertilizer in kilograms."},{"name":"nitrogen_lb","label":"Nitrogen applied","type":"number","unit":"lb","decimals":2,"description":"target_n × area_ft2 / 1000."},{"name":"bags_note","label":"Shopping note","type":"string","decimals":4,"description":"Quantities to buy and the application limit."}],"input_schema":{"type":"object","properties":{"area":{"description":"Area to seed, in the chosen unit.","type":"number","maximum":10000000,"exclusiveMinimum":0,"examples":[5000]},"area_unit":{"description":"Unit of area.","type":"string","enum":["ft2","m2"],"default":"ft2","examples":["ft2"]},"grass_type":{"description":"Grass species or mixture; sets the seeding rate for a new lawn.","type":"string","enum":["kentucky_bluegrass","tall_fescue","perennial_ryegrass","fine_fescue","mix_cool_season","bermuda","bahia","centipede"],"examples":["tall_fescue"]},"seeding":{"description":"New lawn on bare soil, or overseeding into existing grass at half the rate.","type":"string","enum":["new_lawn","overseed"],"default":"new_lawn","examples":["new_lawn"]},"fertilizer_n_percent":{"description":"First number of the N-P-K analysis on the bag (24 for a 24-0-4 fertilizer). Unit: %.","type":"number","maximum":100,"exclusiveMinimum":0,"default":24,"examples":[24],"x-unit":"%"},"target_n_lb_per_1000ft2":{"description":"Nitrogen to apply per 1,000 ft² in this application; starter applications use 0.5–1 lb. Unit: lb N/1000 ft².","type":"number","maximum":3,"exclusiveMinimum":0,"default":1,"examples":[1],"x-unit":"lb N/1000 ft²"}},"additionalProperties":false,"required":["area","grass_type"]},"output_schema":{"type":"object","properties":{"area_ft2":{"description":"Lawn area in square feet. Unit: ft².","type":"number","x-unit":"ft²"},"area_m2":{"description":"Lawn area in square metres. Unit: m².","type":"number","x-unit":"m²"},"seed_rate_lb_per_1000ft2":{"description":"Rate applied (half the new-lawn rate for overseeding). Unit: lb/1000 ft².","type":"number","x-unit":"lb/1000 ft²"},"seed_rate_g_per_m2":{"description":"Same rate in grams per square metre. Unit: g/m².","type":"number","x-unit":"g/m²"},"seed_lb":{"description":"seed_rate × area_ft2 / 1000. Unit: lb.","type":"number","x-unit":"lb"},"seed_kg":{"description":"Seed in kilograms. Unit: kg.","type":"number","x-unit":"kg"},"fertilizer_rate_lb_per_1000ft2":{"description":"target_n × 100 / fertilizer_n_percent. Unit: lb/1000 ft².","type":"number","x-unit":"lb/1000 ft²"},"fertilizer_rate_g_per_m2":{"description":"Same rate in grams per square metre. Unit: g/m².","type":"number","x-unit":"g/m²"},"fertilizer_lb":{"description":"fertilizer_rate × area_ft2 / 1000. Unit: lb.","type":"number","x-unit":"lb"},"fertilizer_kg":{"description":"Fertilizer in kilograms. Unit: kg.","type":"number","x-unit":"kg"},"nitrogen_lb":{"description":"target_n × area_ft2 / 1000. Unit: lb.","type":"number","x-unit":"lb"},"bags_note":{"description":"Quantities to buy and the application limit.","type":"string"}}},"formula":"area_ft2 = area (× 10.7639 if m²); seed_lb = rate_lb_per_1000ft2 × (0.5 if overseed) × area_ft2 / 1000; fertilizer_lb = target_n_lb_per_1000ft2 × 100 / fertilizer_n_percent × area_ft2 / 1000; kg = lb × 0.45359237; g/m² = lb/1000 ft² × 4.882","method":"New-lawn rates are the midpoints of the extension ranges (Penn State for cool-season species, UF/IFAS for warm-season species); overseeding uses half the rate as a rule of thumb, although some services seed thin lawns at the full rate. Nitrogen should not exceed about 1 lb per 1,000 ft² per application (Penn State starter guidance 0.5–1 lb), so larger seasonal totals are split into several applications.","sources":[{"name":"Penn State Extension – Lawn Establishment (seeding rates and starter fertilizer)","url":"https://extension.psu.edu/lawn-establishment","type":"reference","retrieved_at":"2026-09-24"},{"name":"UF/IFAS Extension ENH-03 – Establishing Your Florida Lawn (warm-season seeding rates)","url":"https://edis.ifas.ufl.edu/publication/LH013","type":"reference","retrieved_at":"2026-09-24"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"5,000 ft² new tall fescue lawn, 24-0-4 fertilizer","inputs":{"area":5000,"area_unit":"ft2","grass_type":"tall_fescue","seeding":"new_lawn","fertilizer_n_percent":24,"target_n_lb_per_1000ft2":1},"expected":{"area_ft2":5000,"seed_rate_lb_per_1000ft2":7,"seed_lb":35,"seed_kg":15.88,"fertilizer_rate_lb_per_1000ft2":4.17,"fertilizer_lb":20.8,"fertilizer_kg":9.45,"nitrogen_lb":5},"url":"https://tttkmbb.com/api/v1/calculate/lawn-seed-fertilizer?area=5000&area_unit=ft2&grass_type=tall_fescue&seeding=new_lawn&fertilizer_n_percent=24&target_n_lb_per_1000ft2=1"},{"name":"400 m² bluegrass overseeding, 20-5-10 at 0.75 lb N","inputs":{"area":400,"area_unit":"m2","grass_type":"kentucky_bluegrass","seeding":"overseed","fertilizer_n_percent":20,"target_n_lb_per_1000ft2":0.75},"expected":{"area_ft2":4306,"seed_rate_lb_per_1000ft2":1.25,"seed_lb":5.4,"seed_kg":2.44,"fertilizer_rate_lb_per_1000ft2":3.75,"fertilizer_lb":16.1,"fertilizer_kg":7.32},"url":"https://tttkmbb.com/api/v1/calculate/lawn-seed-fertilizer?area=400&area_unit=m2&grass_type=kentucky_bluegrass&seeding=overseed&fertilizer_n_percent=20&target_n_lb_per_1000ft2=0.75"}],"faq":[{"q":"Why is the seeding rate so different between species?","a":"Seed size: Kentucky bluegrass has about 2 million seeds per pound, tall fescue about 230,000, so fescue needs far more weight to reach the same 15–20 seeds per square inch."},{"q":"How do I convert a 20-5-10 bag?","a":"The first number is the percentage of nitrogen by weight: 20 % means 5 lb of product per pound of nitrogen, so 1 lb N per 1,000 ft² needs 5 lb of that fertilizer per 1,000 ft²."},{"q":"Should new seed get fertilizer at all?","a":"Cool-season lawns benefit from a starter fertilizer at 0.5–1 lb N per 1,000 ft² worked into the seedbed; Florida guidance for warm-season grass is to wait until the lawn is fully covered before adding nitrogen."}],"tags":["grass seed calculator","how much grass seed do i need","lawn fertilizer calculator","seeding rate per 1000 sq ft","overseeding rate"],"related":[{"calculator_id":"area","reason":"Convert the lawn area between square feet and square metres."},{"calculator_id":"plant-spacing","reason":"Plant counts for beds and borders."},{"calculator_id":"gravel","reason":"Aggregate for paths around the lawn."}],"links":{"html":"https://tttkmbb.com/everyday/lawn-seed-fertilizer","markdown":"https://tttkmbb.com/everyday/lawn-seed-fertilizer.md","json":"https://tttkmbb.com/everyday/lawn-seed-fertilizer.json","api":"https://tttkmbb.com/api/v1/calculate/lawn-seed-fertilizer","schema":"https://tttkmbb.com/api/v1/calculators/lawn-seed-fertilizer","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T03:54:30Z","next_actions":[{"tool":"run_calculator","calculator_id":"lawn-seed-fertilizer","reason":"Run Lawn Seed and Fertilizer Calculator with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/everyday/lawn-seed-fertilizer.md"}}