This Free Garden Calculator Does the Math So You Don't Have To 🌱
okay so I've been down a rabbit hole of garden planning tools lately and I finally found one that actually covers everything in one place instead of making you open twelve different tabs
it's called the Grow a Garden Calculator and it lives at — it's free, no account needed, works on mobile, and updates results in real time as you type
here's what it actually does:
🌿 five calculators. one page. zero math on your end.
1. Plant Spacing Calculator you put in your garden size (rectangle, circle, or triangle shape — yes, triangle beds are supported) and it tells you exactly how many plants fit. there's a dropdown with 30+ presets for vegetables, herbs, and flowers, or you can type in any custom spacing. it also lets you choose between square and offset planting patterns — offset fits about 15% more plants in the same space which honestly adds up fast in a small raised bed
2. Soil & Mulch Calculator type in your dimensions and depth, pick your material (topsoil, compost, or mulch), and it spits out cubic yards, cubic feet, and how many bags you need to buy. it even has a cost estimator field so you can price out bulk delivery vs bagged product before you leave the house
3. Watering Calculator not just "one inch per week" — it factors in your garden area, plant type, climate conditions (humid / average / hot-dry), and how often you plan to water. outputs gallons per week, per session, per month, and per year. also includes a watering time estimate so you can set a hose timer correctly
4. Harvest Yield Calculator pick a crop, enter how many plants you have and your season length in weeks, and it estimates total harvest weight, per-plant yield, weekly output, market value, and serving count. works for 15+ crops including tomatoes, cucumbers, kale, potatoes, beans, zucchini, and more
5. Fertilizer (NPK) Calculator enter your garden area and NPK ratio — there are presets for 10-10-10, 5-10-5, and 20-20-20 — and it tells you exactly how many pounds to apply, how much per application if you're splitting doses, and gives you a full broadcast schedule
🎮 also works for roblox grow a garden players
if you play the roblox game this is also your tool. it has mutation rate calculations, crop value estimates for trading, plot spacing optimization, and yield forecasting for in-game planning. the community around that game is huge right now and having actual numbers behind your decisions makes a real difference
some things I actually appreciate about this tool
✔ works in feet, meters, inches, AND centimeters — no unit conversion needed
✔ supports rectangular, circular, AND triangular garden shapes
✔ the visual layout preview in the spacing tab is genuinely useful for raised bed planning
✔ all five tabs stay loaded — switch between them without losing your inputs
✔ no ads interrupting your workflow, no paywall, no email required
🌱 first-time gardeners figuring out how much of anything to buy
🌱 raised bed builders doing material calculations before ordering soil
🌱 homesteaders planning harvests for preservation and canning
🌱 anyone who has ever bought too much or too little topsoil (we've all been there)
🌱 roblox grow a garden players optimizing plots and trades
quick plant spacing reference since we're here
plantspacingexpected yield🍅 tomatoes18–24"10–15 lbs/plant🥒 cucumbers12"~10 lbs/plant🥬 lettuce6–12"~0.5 lbs/plant🥕 carrots2–4"~0.5 lbs/plant🫑 zucchini24–36"6–10 lbs/plant🥔 potatoes10–12"5–10 lbs/plant🌽 corn8–12"1–2 ears/plant
the full tool is at 👉 smartcalculatortool.com/grow-garden-calculator/
five calculators, completely free, no login. honestly just keep it bookmarked for whenever you're planning a new bed or expanding your garden