New HarvestMath Garden plans your whole garden in five minutes.

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New: HarvestMath Garden

Your whole garden, planned in five minutes

ZIP code, a starter garden and your space: frost dates, layout, watering, shopping list and every job on a calendar.

One-time purchase. Works offline. Your garden stays on your device.

Plan it once. Keep it for good.

10 planners and one app that does it all. Pay once, no subscription, works offline. Try the real app free first.

10 free books. Just an email.

Short, practical PDFs: seed rates, planting dates, feeding, watering and more. Pick one, or take the five planning books together.

Free garden and plant calculators

31 free calculators in eight groups, from the soil you start with to the lawn, beds and houseplants it becomes. No sign-up.

Find the right calculator for whatever season your garden is in. Explore

Live now

Jump into any of these right now — no waiting, no roadmap to squint at. New calculators join the list most weeks.

Live

Mulch Calculator

Calculate how much mulch you need in cubic feet, cubic yards, and 2-cubic-foot bags for any garden bed or landscape area, plus a bale count for pine straw.

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Pine Straw Calculator

Calculate how many bales of pine straw you need for any bed, border or tree ring, from extension coverage you can adjust to your bale, with an optional cost estimate.

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Cover Crop Seed Calculator

Cover crop seed in pounds and ounces for any bed or plot, using extension seeding rates for broadcast or drilled sowing, with mixes and a seed cost estimate.

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Cubic Yard Calculator

Convert between cubic yards, cubic feet, tons, and dimensions for dirt, gravel, or mulch: a unit-conversion tool, not a how-much-do-I-need calculator.

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Topsoil Calculator

Calculate how much topsoil you need in cubic yards, cubic feet, and estimated tons for raised beds, garden filling, and lawn leveling.

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Raised Bed Soil Calculator

Calculate exactly how much soil you need for a raised bed in cubic feet, cubic yards, and bags. Includes presets for common bed sizes.

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Soil Volume Calculator

Calculate how much soil you need to fill a pot, container, raised bed, or any rectangular or cylindrical space, in cubic feet, cubic yards, and liters.

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Plant Spacing Calculator

Calculate how many plants fit in any bed using proper in-row and between-row spacing. Supports row garden and square foot gardening modes with crop presets for 20+ vegetables, herbs, and flowers, plus a Trees & Shrubs mode with real mature spacing for fruit trees, pecans, and landscape shrubs.

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Bulb Planting Calculator

Calculate how many flower bulbs to buy for a bed in sq ft or m², with planting depth and spacing for tulips, daffodils, crocus, hyacinth, alliums, and more, from university extension tables.

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Plants per Acre Calculator

Calculate plant population from in-row and between-row spacing per acre, per hectare, per 1,000 sq ft, and per sq ft. Work back from a target population, lay out beds with paths, and size your seed or transplant order for germination and survival.

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Grass Seed Calculator

Calculate how many pounds and 50 lb bags of grass seed you need by grass type, for a new lawn or for overseeding an existing one.

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Overseeding Calculator

Calculate how much grass seed and topdressing you need to overseed an existing lawn, by grass type and lawn condition.

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Sod Calculator

Calculate how much sod you need in square feet, pallets, and individual pieces, by grass type and lawn shape.

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Frost Date Calculator

Estimate your last spring frost and first fall frost date range by ZIP code or hardiness zone, then get a full planting timeline built around it.

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USDA Hardiness Zone Finder

Find your exact USDA plant hardiness zone by ZIP code, plus the average annual minimum winter temperature range that zone represents.

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Tree Age Calculator

Estimate how old a tree is from its trunk circumference and species. No cutting or coring required.

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NPK Calculator

Calculate fertilizer application rates, mix a liquid feed solution, or blend multiple fertilizers to approximate a target N-P-K ratio.

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Pot Size Calculator

Convert pot sizes between inches, gallons, and liters, find the recommended next size up when repotting, or look up the minimum container size for a plant or vegetable.

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Compost Calculator

Calculate how much compost you need in cubic feet, cubic yards, bags, and estimated weight, for top-dressing beds, containers, or mixing into new soil.

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Soil Type Calculator

Classify your soil texture using the official USDA soil triangle, from sand, silt, and clay percentages or jar test measurements.

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Seed Starting Calendar

Get a personalized seed starting calendar based on your frost date: when to start seeds indoors, when to transplant, and when to direct sow, by crop.

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Drip Irrigation Calculator

Calculate drip irrigation run time and total water delivered based on your emitter count, flow rate, and target water amount per plant or over an area.

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Lawn Irrigation Calculator

Work out sprinkler run time per zone for your lawn: minutes per watering day and per week, gallons per week, cycle and soak for clay, and a catch-can test helper.

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Rain Barrel Calculator

Calculate how much rainwater you can collect from your roof, and the water pressure from your rain barrel spigot.

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DLI & Grow Light Calculator

Calculate Daily Light Integral (DLI) from a PPFD reading, recommended grow light wattage and electricity cost for your growing area, or recommended hanging distance for your light and growth stage.

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Greenhouse Heater Calculator

Calculate your greenhouse's heat loss and the recommended heater size in BTU/hr, by shape, glazing type, and climate.

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Hydroponic Nutrient Calculator

Calculate hydroponic nutrient dosing by reservoir size and growth stage, and convert EC readings to PPM on all three common scales.

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Vegetable Yield Calculator

Estimate how much food your garden will produce, by crop and either plant count or growing area, using published yield data.

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Growing Degree Days Calculator

Calculate growing degree days (GDD/GDU) from daily high and low temperatures, with base temperature presets, the 86/50 cap, and single-day or season-long accumulation tracking.

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Tree Height Calculator

Measure a tree's height three ways (clinometer angle, shadow ratio, or the stick method) without climbing, including a slope correction for sloped ground.

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Tree Planting Calculator

Work out how many trees fit an area at extension-published spacing (grid, triangular, or a single row), plus the planting hole, mulch volume, and watering for every tree.

Guides for Every Stage of the Garden

Calculators answer “how much do I need.” These guides cover the rest — what to plant when, what’s gone wrong, and how to fix it.

Built for the way you actually garden

Most gardening sites bury the calculator under ads and a wall of life-story before you get an answer. We’d rather get you back outside — the tool comes first, the explanation is there if you want it, and nothing else gets in the way. Every calculator updates live as you type, works fine on your phone in the store aisle, and answers in the units you’re actually going to buy — bags, cubic feet, pounds.

  • Live results. No submit button. Type your numbers, get your answer.
  • Buyable units. Cubic feet, cubic yards, 2-cu-ft bags, pounds — what the store actually sells.
  • Mobile-first. Big tap targets, no zooming, no popups. Pinterest-friendly.
  • No sign-up. No account, no email wall, no upsell. Just the math.

Example output

Mulch for a 4'x8' bed at 3" deep

Cubic feet
8.0
Cubic yards
0.30
2-cu-ft bags
4
Open the Mulch Calculator

5 free books · 120 pages, PDFs

Five free books: planting dates and spacing, companion beds, feeding, soil and watering.

We email the books right away, then a few short emails over the next week or two. After that, about one email a month. Unsubscribe anytime. Privacy policy

5 free books · 120 pages, PDFs

The Garden Starter Bundle

Five free books: planting dates and spacing, companion beds, feeding, soil and watering.

We email the books right away, then a few short emails over the next week or two: a tip from them and how our garden apps can help. After that, about one email a month. Unsubscribe anytime. Privacy policy