Garden Calculators & Feed Charts

Take the guesswork out of indoor and outdoor cultivation with our comprehensive suite of grow calculators. Access official manufacturer feed charts from leading nutrient brands alongside precision tools for soil volumes, extraction sizing, and running costs to ensure every parameter in your grow space is dialled in.

Feed Charts & Soil Calculators

  • Manufacturer Feed Charts: Instantly access official weekly feeding schedules, dilution rates, and EC guidelines for top brand lines including Shogun, BioBizz, Canna, Plagron, and more.
  • Custom Mix Recipes: Calculate tailored soil and substrate ratios for vegetables, root crops, herbs, and flowering plants.
  • Any-Shape Mulching: Effortlessly calculate volume requirements for square, round, or irregular beds and borders.
  • Zero Waste Volume: Buy the exact amount of soil, coco, or amendments in litres with zero wasted spend.
  • Potting Up Pro: Instantly calculate the precise gap volume required when stepping plants up to larger pots.
  • Biochar Ratios: Determine the safe, effective percentage of Biochar to add to your pots and raised beds.
  • Soil pH Adjustment: Calculate the exact amount of Citric Acid or Agricultural Lime needed to bring your soil pH into the target range.

Equipment & Environment Calculators

  • Extraction Fan Sizing: Find the correct CFM or m3/h air displacement rating required to properly ventilate your grow space.
  • Grow Tent Sizing: Calculate the ideal tent footprint based on plant count, pot sizes, and canopy layout.
  • Lighting Coverage & Wattage: Work out optimal light intensity, power draw, and coverage area for your grow.
  • Electricity Running Cost: Estimate exact daily, monthly, and per-cycle energy usage for all your lights, fans, and climate gear.

Soil Calculators

🪴

Soil Volume

Beds or tapered pots.

🧪

Potting Mix Pro

Custom crop recipes.

⛰️

Biochar Rate

Volume or Allotment m².

⚖️

pH Adjustments

Citric Down / Lime Up.

🪵

Mulch Volume

Now with Wavy Borders.

📈

Potting Up

Math for pot upgrades.

×

Equipment Calculators

⚡

Electricity Cost

Calculate daily & monthly running costs in £.

💧

Humidity Sizer

Humidifier tank & dehumidifier pint capacity.

💡

LED Wattage Sizer

Veg & Flower wattage recommendations.

🌀

Ventilation Sizer

Airflow & extraction requirements.

🪴

Plant Capacity

Plant count by tent size & training method.

Feed Charts

📋

Nutrient Feed Schedules

Select your nutrient brand and line to view official feeding charts.

Need Anything?

Pro-Tips for using your results

When filling a new raised bed, soil will naturally settle by about 10-15% after the first few waterings. We recommend buying 10% extra to "top up" after the first week.


When measuring a wavy garden border, lay a garden hose along the curve, then straighten the hose and measure it with a tape measure to get the exact "Path Length."

In our Potting Mix Pro recipes, "Aeration" can be Perlite (for lightweight pots), Pumice (for permanent long-term drainage), or even Coarse Sand (for Mediterranean herbs).

When applying mulch, don't pack it down with your feet. Let gravity and water do the work to keep the air pockets intact for soil health.

Biochar is a lifetime investment in your soil, but it must be used correctly. Never add 'raw' biochar directly to your plants, it acts like a sponge and will suck the nitrogen right out of your soil. Always 'Charge' your biochar first.

You'll notice our calculator asks if your soil is Sandy or Clay. This is because of 'Buffering Capacity.' Clay soil is chemically stubborn, it takes much more sulfur or lime to move the pH needle in clay than it does in sandy soil. Always be patient, pH changes are a marathon, not a sprint!

To size an extraction fan, calculate your grow space volume in m³ (length × width × height) and aim for a fan that can exchange the air at least every 1–3 minutes. Our Extraction Fan Calculator on this page does the maths for you — just enter your tent dimensions and it'll recommend the right m³/hr rating.

As a general rule, aim for 200–400W of actual power draw per m² depending on your target light intensity and crop type. Our Lighting Calculator factors in your grow area and target PPFD to help you choose the right number and wattage of lights for your setup.

A feed chart is a week-by-week nutrient dosing schedule provided by the manufacturer of your chosen nutrient brand. It tells you exactly how much of each product to add per litre of water at each stage of growth. Download brand-specific feed charts from the Feed Charts section on this page and follow the schedule, adjusting up or down based on how your plants respond.

To estimate running costs, multiply your equipment's total wattage by the number of hours it runs per day, divide by 1000 to get kWh, then multiply by your electricity unit rate (pence per kWh). Our Electricity Cost Calculator on this page automates this so you can quickly see your daily, weekly, and per-cycle running costs.