Free grow calculators for every crop
Tools that do the grower math for you — nutrient conversions, environmental targets, tent sizing, substrate recipes, light intensity. Pick your crop to see the tools that matter for your grow.
Tools curated for what you grow
Every crop has its own environmental targets, nutrient needs, and growing workflow. Each crop hub below is a curated toolkit — only the calculators that matter for that species, framed for that species.
Cannabis Tools
The full cannabis grower toolkit. VPD, PPM/EC, tent sizing, light intensity, nutrient mixing, harvest timing, training schedules. Home grow to small commercial.
Mushroom Tools
Substrate recipes, fruiting chamber climate, spawn ratios, species-specific targets. Built for monotub growers, Martha tent growers, and everything between.
Microgreens Tools
Seeding density, soak and rinse schedules, light timing, harvest windows. Everything for the 7 to 14 day growth cycle.
Herbs Tools
Indoor herb garden planning, pot sizing by variety, companion planting, harvest rotation for continuous yield.
Vegetables Tools
Indoor vegetable yield estimators, pot sizing, light requirements by crop, harvest rotation for leafy greens to fruiting vegetables.
Bonsai Tools
Watering schedules, pruning timers, soil composition, wiring timing. Species-specific care for indoor and outdoor bonsai.
Jump straight to a calculator
Questions about the tool suite
Are these tools really free?
Yes. Every tool on this site is free to use, no account required, no daily limits, no watermark. We built them because growers were using spreadsheets and napkin math to make decisions that deserve better inputs. If you want more — persistence across sessions, AI-powered troubleshooting, grow journal integration — that's what grohaus.app provides. But the calculators themselves stay free forever.
Why are tools organized by crop instead of by function?
Growers think in crops, not functions. A cannabis grower looking for environmental tools doesn't want to wade through mushroom fruiting chamber calculators. A mushroom grower doesn't need to scroll past tent sizing for cannabis canopies. Each crop hub pulls together the tools that matter for that species, with stage targets calibrated for that species. Tools that apply to multiple crops (like VPD) include a crop selector so you get the right targets for your grow.
Which tool should I start with?
Depends on where you are. If you're planning a new grow, start with the Grow Tent Sizer — it tells you what equipment to buy and in what sizes. If you're already running plants, start with the VPD Calculator and the PPM/EC Converter — those are the two daily-use measurements that separate average grows from great ones. If you're growing mushrooms, the Substrate Calculator is the obvious first stop.
How do these compare to paid grow apps?
Paid apps bundle calculators with grow journals, task calendars, and photo tracking. They're persistence tools first, calculators second. Our free tools are calculators first — each one is a full-featured, dedicated page for its specific calculation, with deeper educational content than most paid tools include. If you want the calculators only, stay here. If you want persistence and AI advice on top, grohaus.app handles that. We don't try to be both.
Can I trust the numbers?
Yes, with a caveat. Every calculator uses peer-reviewed or industry-standard formulas — VPD uses the Magnus equation, PPFD/DLI follows published conversion coefficients, EC/PPM scales use the verified 500 and 700 conversion factors. The math is right. The application of the math to your specific situation depends on variables the calculator can't see: your genetics, your medium, your growing experience. Calculators are starting points, not verdicts.
How often do new tools ship?
Weekly to monthly, depending on complexity. Simple tools (pH drift tracker, pot size calculator) ship in a few days each. Complex tools with novel math (the Substrate Calculator, the Fruiting Chamber Calculator) take longer because we build and test the underlying formulas before shipping the interface. Grōbot will notify you when a tool relevant to your crop ships if you tell it what you're growing.