25 live calculators, growing every week

Free Garden & Plant Calculators

Do the math. Then go get your harvest.

Whatever you’re growing — a raised bed, a new lawn, a windowsill full of houseplants — getting the numbers right is what turns a planting day into a harvest you’re actually proud of. Free calculators for mulch, soil, fertilizer, watering, spacing, and more. No sign-up, no fluff, just enough math to get you back outside.

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

Find the tools for what you’re growing

Eight clusters, each built around a different part of the garden — from the soil you start with, to the lawn, beds, and houseplants it all becomes.

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Soil & Amendments

Build healthy ground from the bottom up. Calculate exact volumes for raised beds, garden plots, and topdressing without overbuying.

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Fertilizer & Nutrients

Match the right fertilizer to the right plant at the right dose. NPK math, feeding rates, and nutrient budgets made simple.

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Watering & Irrigation

Water smarter, not more. Drip emitter counts, run times, and weekly water budgets tuned to your plants and climate.

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Spacing & Planting

Plan beds that fit. Spacing, row layout, and plant count math for raised beds, square-foot gardens, and traditional rows.

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Lawn & Landscaping

Get the right amount the first time. Grass seed, sod, mulch, and landscape material math for lawns and paths of any shape.

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Indoor Plants

Keep houseplants thriving. Pot size, watering frequency, and light calculators tuned to container-grown indoor plants.

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Hydroponics & Greenhouse

Grow more in controlled environments. Nutrient solutions, EC targets, and greenhouse heating math for soil-free growing.

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Trees & Shrubs

Understand your trees and shrubs without cutting them down. Estimate age, growth, and value from a simple trunk measurement.

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Live now

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

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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 — including a bale count for pine straw.

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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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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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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.

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.

Diagnose a Problem

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Guide

Why Are My Plant Leaves Turning Yellow?

Diagnose by pattern — old leaves vs. new, whole-leaf vs. between the veins — to find the real cause.

 Guide

Why Is My Plant Wilting?

Sudden vs. gradual, soil-wet vs. soil-dry — the two quick checks that narrow it down fast.

 Guide

Why Are My Tomato Leaves Turning Yellow?

Bottom-up yellowing, spots, or curling each point to a different cause and fix.

Crop Guides

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Guide

How to Grow Tomatoes from Seed

Germination temps, the heat mat mistake to avoid, and when to transplant.

 Guide

Growing Tomatoes in Raised Beds

Spacing and bed depth, plus why raised beds get blossom end rot more often.

 Guide

How to Start a Vegetable Garden

A complete beginner's guide — pick the spot, size it right, choose what to plant first.

Guides & How-Tos

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Guide

Companion Planting Chart

What to grow together, what to avoid, and why — for vegetables and herbs.

 Guide

How to Read Your Soil Test Results

pH, organic matter, N-P-K, and how to turn them into an actual fertilizer plan.

 Guide

8 Mulch Mistakes That Are Secretly Hurting Your Plants

From volcano mulching to guessing the amount — and exactly how to avoid each one.
Browse All Guides

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