Gardening Calculators & Converters
Save to PinterestFive tools for gardeners, landscapers, and backyard growers: a seed spacing calculator that converts row length and plant spacing into a plant count; a lawn seed and fertilizer quantity estimator from area and application rate; a rainfall converter between millimeters and inches for comparing weather data and irrigation specs; a mulch and topsoil volume calculator from area and depth to cubic yards; and a USDA Plant Hardiness Zone lookup by ZIP code that identifies your zone and typical minimum winter temperature. Hardiness zone data is sourced from the USDA 2023 Plant Hardiness Zone Map — a direct verification link is shown next to every result.
All Gardening Tools
Rainfall Converter — mm to Inches
Convert rainfall between millimeters and inches instantly. 1 inch = 25.4 mm exactly (NIST SP 811). Useful for comparing weather data and irrigation specs.
Seed Spacing Calculator — Plants per Row
Calculate how many plants fit in your garden rows. Enter row length, plant spacing, and number of rows to get total plant count.
Lawn Seed Calculator — Pounds Needed
Calculate how many pounds of grass seed you need. Enter lawn area and your seed's application rate. Supports new seeding and overseeding rates.
Mulch Calculator — Cubic Yards and Bags
Calculate how much mulch, topsoil, or compost you need in cubic yards and bags. Enter area and depth — works for any loose landscaping material.
USDA Hardiness Zone Lookup by ZIP Code
Find your USDA Plant Hardiness Zone by ZIP code. Shows zone code and minimum temperature range (°F and °C). Data from USDA 2023 PHZM.