Free, accurate garden planning calculators — built for home gardeners who want real answers, not guesswork.
"Every gardener deserves the same tools that professional growers use — without the paywall, the sign-up form, or the PDF download from a 2003 university extension page."
GardenCalcs is a free collection of garden planning calculators built specifically for home gardeners. Whether you're figuring out how many tomato plants fit in your raised bed, how much fertilizer to apply, or how many seeds to buy for spring planting — we built a tool for it.
Every calculator on this site works instantly in your browser, on any device, with no account required. Just enter your numbers and get your answer.
The formulas behind every GardenCalcs calculator are based on established horticultural guidelines from university cooperative extension services, USDA publications, and peer-reviewed gardening research. We don't invent numbers — we translate trusted agronomic data into tools that anyone can use.
Each calculator is tested across a wide range of inputs to make sure results are accurate and practical for real home gardens. Where ranges exist in the scientific literature, we present them honestly rather than picking a single arbitrary number.
Formulas grounded in university extension research and established horticultural practice.
No paywalls, no sign-ups, no email required. Every tool is free to use, forever.
Fully responsive on phones, tablets, and desktops. Use it in the garden on your phone.
No loading spinners, no server calls. Every calculation happens instantly in your browser.
We built GardenCalcs for the backyard vegetable grower who's tired of rough guesses and vague advice. Whether you're planting your first raised bed or expanding a well-established kitchen garden, these tools give you the specific numbers you need to plan with confidence.
GardenCalcs is especially useful for:
Gardeners setting up new raised beds and trying to figure out exactly how much soil to buy. Anyone applying fertilizer who wants to know the right amount based on their actual NPK product, not a generic "handful per plant" suggestion. Growers doing succession planting who need to know how many seeds to order. Anyone who's ever wondered whether their 4×8 bed can fit 6 tomatoes or 8.
Have a suggestion for a new calculator? Found an error in one of our formulas? We'd love to hear from you.
Reach us at: calcs.site@gmail.com