Hydroponic Nutrient Calculator
Enter your reservoir size and the dose on your nutrient label for each part. You get the amount of each part to add, in ml, teaspoons and fluid ounces.
How the calculation works
The label dose is per unit of water, so the amount to add is the dose multiplied by how many of those units are in your reservoir:
Amount (ml) = dose (ml per unit) × reservoir volume (in the same unit)
Example: a 20 L reservoir with Part A at 2 ml/L, Part B at 2 ml/L and Part C at 1 ml/L needs 2 × 20 = 40 ml of A, 40 ml of B and 1 × 20 = 20 ml of C. If your label is in ml per US gallon, the tool first converts your reservoir to gallons (20 L ÷ 3.785 = 5.28 gal).
Teaspoon figures use 4.93 ml per US teaspoon and fluid ounces use 29.57 ml. Filling a bucket? See how much nutrient for a 5-gallon bucket. For small amounts, a syringe or marked pipette is more accurate than a spoon. After mixing, check the result against your target with the EC to PPM converter.
Always follow the mixing order and doses on your nutrient label. Check pH and EC with calibrated meters after mixing.
Frequently asked questions
Where do I find the dose for my nutrient?
On the bottle label or the manufacturer's feeding chart. Doses are usually given per litre or per US gallon, often per week of growth. Enter those numbers here for each part of your nutrient.
Why are there separate parts?
Many nutrients are sold as two or three bottles (such as Part A, Part B and Part C, or Grow, Micro and Bloom) because some ingredients react and precipitate if stored together in concentrate. Add each part to the water separately and stir in between, as the label directs.
Should I start with a lower dose?
Many growers start at a quarter to a half of the label dose for seedlings and young plants and work up while watching EC and plant response. Follow your nutrient maker's guidance for your crop.
Can I use this for powdered nutrients?
This tool works in millilitres, for liquid concentrates. For powders, measure by weight with a scale as the label directs.