Meridian includes 15 free interactive calculators designed for indoor growers. They work without an account and save your recent calculations automatically.
Available tools
Environment
VPD Calculator — Enter air temperature, humidity, and optional leaf temperature offset to get your Vapor Pressure Deficit. Color-coded ranges for seedling, veg, and flower stages.
DLI Calculator — Calculate your Daily Light Integral from PPFD and photoperiod. Tells you if you're hitting optimal light levels for your plant type.
CO2 Calculator — Estimate supplementation rates, cost per month, and target PPM by growth stage.
Lighting
PPFD Map — Visualize light distribution across your grow space. Enter your light and hanging height to see center vs. edge intensity.
Light Calculator — Plan hanging height and intensity for your specific light and space combination.
Nutrients & Water
EC/PPM Converter — Convert between EC (mS/cm), PPM-500, and PPM-700 scales. Every meter brand uses a different scale — this clears up the confusion.
pH Calculator — Target pH ranges by growth stage, growing medium, and crop type.
Nutrient Calculator — Mix ratios and feeding schedules for common nutrient lines.
Feed Schedule Builder — Build a custom week-by-week feeding program.
Equipment & Space
Dehumidifier Sizing — Calculate the pints/day capacity you need based on your space volume and target humidity.
Reservoir Calculator — Volume calculations for reservoir sizing and nutrient mixing.
Substrate Calculator — How much growing medium do you need for your containers?
Power Budget — Estimate monthly electricity costs from your equipment list.
Air Exchange — Calculate the CFM your exhaust fan needs based on space volume and desired air exchange rate.
Equipment Fit — Will that light or fan physically fit in your tent? Enter dimensions and find out.
How to access them
Tap Tools in the sidebar, or visit growmeridian.com/tools. Each tool is also directly accessible at its own URL (e.g., /tools/vpd-calculator).
No account needed
All calculators work without logging in. If you do have an account, your recent calculations are saved for easy reference.