Free garden calculators
Garden math, done in your browser.
Instant calculators for mulch, soil, compost, topsoil, raised beds, and plant spacing. Type your measurements — get cubic yards, bags, and cost on the spot. No sign-up.
Mulch Calculator
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Free, from NOAA climate data
Frost Dates by ZIP Code
Last spring frost, first fall frost, and USDA hardiness zone for your US ZIP, at 10/50/90% risk, with the weather station behind every date.
- 30 years of station records
- 2023 USDA zone map
- CSV download
- Duluth, MN149 frost-free days
- Denver, CO156 frost-free days
- Chicago, IL208 frost-free days
- Atlanta, GA231 frost-free days
- Austin, TX252 frost-free days
- Sacramento, CA341 frost-free days
For people who’d rather measure once than guess and reorder.
Every calculator uses US units by default, with a metric toggle. We check the math against each formula, and spacing, depth, and timing against university extension and USDA sources. See our methodology.
No account or download needed. Results update as you type, right in your browser. Your measurements aren’t sent to a server or saved.
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Calculators
- 01Compost CalculatorTop-dress or amend a bed — cubic yards, bags, and tons.Open calculator →
- 02Plant Spacing CalculatorHow many plants fit — square, triangular, or square-foot grid.Open calculator →
- 03Topsoil CalculatorOrder by the yard or the ton, bagged vs bulk.Open calculator →
- 04Mulch CalculatorStop overbuying — yards, bags, and coverage at your depth.Open calculator →
- 05Raised Bed Soil CalculatorA full mix shopping list: topsoil, compost, and aeration.Open calculator →
- 06Soil CalculatorGarden soil, fill dirt, or a custom depth.Open calculator →
- 07Garden Soil CalculatorBed size and depth to cubic yards, bags, and cost.Open calculator →
- 08Garlic Planting CalculatorCloves needed and spacing for any bed size.Open calculator →
- 09Bulb CalculatorHow many fall bulbs fit your bed, by spacing.Open calculator →
- 10Leaf Mulch CalculatorBags of leaves needed, whole or shredded.Open calculator →
- 11Cover Crop CalculatorSeed by weight for your bed size and crop.Open calculator →
- 12Lawn Topdressing CalculatorCompost, topsoil, or sand for your lawn size.Open calculator →
Read first
Popular guides
Our most-read planting and harvest guides — the ones people search for most.
- 01How Far Apart to Plant Lettuce (Rows + Raised Beds)Spacing by row, raised bed, and lettuce type.
- 02How Far Apart to Plant OnionsSets vs. transplants, plus bulb size at harvest.
- 03How Far Apart to Plant GarlicClove spacing for the biggest bulbs at harvest.
- 04How Far Apart to Plant RadishesTight spacing for a fast, crowded-free crop.
- 05How Far Apart to Plant CarrotsThinning distance for straight, uncrowded roots.
- 06How Far Apart to Plant Spinach (Rows + Raised Beds)Row and square-foot spacing for leafy growth.
- 07How Far Apart to Plant Sweet PotatoesSlip spacing for vines that need room to sprawl.
- 08How Far Apart to Plant Butternut SquashHill and row spacing for a sprawling vine.
- 0913 Cabbage Companion Plants (and What to Avoid)What to plant near cabbage, and what to avoid.
- 10When to Harvest Sweet Potatoes (Signs They're Ready)The signs your slips are finally ready to dig.
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How to use these tools
Quick answers
How many bags of mulch are in a yard?
A cubic yard is 27 cubic feet, so it's about 13.5 standard 2-cubic-foot bags — round up to 14.
Try the calculator →How much soil does a 4×8 raised bed need?
At a 10-inch fill depth, that's about 26.7 cubic feet — roughly 1 cubic yard.
Try the calculator →How far apart should tomatoes be planted?
About 24 inches apart in a row, or one plant per square foot in square-foot gardening.
Try the calculator →How much compost do I need to top-dress a bed?
For a 1-inch layer, budget about 8.3 cubic feet per 100 sq ft (100 × 1 ÷ 12).
Try the calculator →The why behind the numbers
Not sure how deep to mulch, or how much soil a 4×8 bed needs?
Our plain-English guides explain the formula, the reference numbers, and the common mistakes — so the calculator result actually makes sense.