Hydroponic Calculators
Seven free tools built for apartment growers. No signup, no email, no nonsense. Pick the one you need and get exact numbers for your setup in under 60 seconds.
Not sure which one you need?
Pick one and get your numbers
pH and Nutrient Calculator
Pick your crop and system type, then enter your reservoir size. Get exact pH range, EC target, PPM, water temperature, and nutrient doses in milliliters. Covers 39 hydroponic crops.
Beginner Shopping List Builder
Tell us what you grow, where it grows, how you want to run it, what you already own and your budget. Get a complete prioritized shopping list with every item explained, what to buy first, what can wait, and direct Amazon links. Live prices, no guesswork.
Grow Light Calculator
Enter your grow space size and crop type. Get the exact PPFD target, true wattage needed, daily light hours, hang height, and DLI. It also works for LED panels, bars and all-in-one kits.
Seed to Harvest Countdown
Enter your crop and planting date. See your current growth stage, estimated harvest date, days remaining, and the exact signs to look for when it is ready to pick. It updates every day, so you always know where the plant is.
Printable Hydroponics Tracker
A free two page PDF for the jar itself. Page one logs 14 days of top offs, pump checks, pH and EC. Page two holds the weekly check, the reservoir change list, and the numbers. Letter and A4.
Grow Planner
Pick a crop, a jar or bucket and a start date, and the planner writes the day-by-day care list: water checks, pH days, root checks, lights out and the harvest window. It runs in your browser and keeps your plants on this device; sign in with Google only if you want them on your phone too.
Running Cost Calculator
See what your garden costs a month to run: electricity for each light and pump, nutrients, and pods or seeds. US, UK, Canada and Australia electricity prices are filled in, and every number can be changed to match your bill.
Apartment Hydroponics for Beginners
The same six numbers and the same 39-crop chart, in order, from picking a system to a realistic first 90 days. Paperback and Kindle, free to read on Kindle Unlimited.
One worked example, start to finish
This is a real result from the grow light calculator, not a mockup. In fact, every tool answers in the same shape: you give it your setup, it gives you numbers you can act on the same afternoon.
Six numbers, one screen, no unit conversion in your head. The pH calculator, likewise, answers the same way with pH range, EC target, PPM and milliliters of nutrient. The countdown, meanwhile, answers with a harvest date and what to look for.
Four tools, one first grow
Shopping list
Five quick questions, including what you already own. You get the list in buying order, so you do not spend on a pump you never needed.
Build my list →Grow light
Measure the space the plants will actually occupy rather than the whole shelf. Get the wattage, the hang height and the schedule before the panel arrives.
Calculate my light →pH and nutrients
Your crop, your system, your reservoir size. Starting doses in milliliters, so the first mix starts close instead of a guess you correct for two weeks.
Get my recipe →Harvest countdown
Planting date in, growth stage and harvest date out, plus the signs to watch for. The one you keep open while the others sit idle.
Start my countdown →
I built these because I spent my first month guessing. Not at the hard things, but at the ordinary ones. How much light, how much nutrient, how long until I could eat any of it. The answers exist; however, they are scattered across forums written for greenhouses.
All tools are free forever with no signup required. Built by Urban Hydro Space for apartment growers who want real answers rather than vague advice. Every number is backed by research and verified math.
Common questions
I am a complete beginner. Which tool should I use first?
Start with the Shopping List Builder. It asks three questions and then gives you everything to buy, split into what to buy first and what can wait, with links and live prices. Once your equipment arrives, the pH and Nutrient Calculator sets up your first mix, and after that the Seed to Harvest Countdown tracks the grow.
Are these tools really free?
Yes. They are free, with no signup, no email gate and no limits. However, the tools do contain Amazon affiliate links, so if you buy through one of them we earn a small commission at no extra cost to you. That is how the tools stay free.
How accurate are the calculations?
Every number comes from verified source data rather than hardcoded guesses. For example, PPM is computed from EC with the standard 700 scale, and DLI is computed from PPFD and light hours. Similarly, wattage comes from your grow area and the watts per square foot your crop needs. Finally, the shopping list uses live Amazon prices, and anything without a current price is shown as unpriced instead of being counted as zero.
What crops do the tools support?
The pH Calculator and the Seed to Harvest Countdown each cover 39 crops, including lettuce, spinach, arugula, basil, mint, cilantro, chives, tomatoes, peppers, cucumbers, strawberries, microgreens, bok choy, wheatgrass and edible flowers. The Grow Light Calculator, on the other hand, works by crop group, with 7 groups ranging from seedlings and microgreens to woody herbs, fruiting vegetables and strawberries. Finally, the Shopping List Builder covers herbs, fruiting crops, microgreens and mixed setups.
Do the tools work on mobile?
Yes. All the tools are fully responsive, so they work on phones, tablets and desktop browsers alike. In addition, the buttons, input fields and results all adapt to your screen size automatically.