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Nutrient Solution Dosing Calculator

Work out exactly how much nutrient concentrate to add to your reservoir, scaled from your product's own full-strength dose to match your reservoir size and your plants' growth stage.

Amount to add87.5 mL/g

How to measure your inputs

  • Full-strength dose: copy this directly from your nutrient product's label (usually given per litre or per gallon).
  • Reservoir size: the actual volume of nutrient solution in your system.

Methodology

Proportional strength scaling: dose = full-strength dose per litre × reservoir litres × strength percentage. Deliberately avoids EC/PPM conversion, since those scales differ by meter/manufacturer in ways that would make a single target figure genuinely ambiguous.

Dosing nutrients by growth stage, not just by the label

Why this calculator doesn’t use EC or PPM

EC-to-PPM conversion uses different industry scales (commonly "500" and "700") depending on your meter and manufacturer — a PPM figure from one source can mean a meaningfully different actual concentration than the same PPM figure from another. Rather than pick one scale and risk being wrong for your specific meter, this calculator scales your product’s own labeled dose proportionally, which sidesteps the ambiguity entirely.

Why seedlings need less than mature plants

Young seedlings and clones have limited root systems and are more sensitive to nutrient concentration — full-strength solution can burn tender roots. Starting at 25-50% strength and increasing as the plant matures is standard practice across most hydroponic and vertical-farm growing guides.

Why flowering/fruiting stages often go above 100%

Fruiting crops in their reproductive stage have higher nutrient demand than the same crop in vegetative growth, which is why some growers push above the "standard" labeled dose during flowering/fruiting — within the range the specific product’s manufacturer considers safe.

Frequently asked questions

Why isn't there a single 'correct' PPM number for my crop?

Because PPM readings depend on which conversion scale your meter uses (commonly 500 or 700), a "1500 PPM" target from one source and another source can mean genuinely different actual concentrations. EC in mS/cm is more consistent between meters, but still varies by manufacturer calibration — which is why this calculator works from your product’s own labeled dose instead.

Can I use this for soil-based fertigation, not just hydroponics?

Yes — the same proportional-dosing logic applies to any liquid feed product with a labeled full-strength dose per litre, whether it’s going into a hydroponic reservoir or a soil-based drip/fertigation system.

What if my nutrient product doesn’t list a dose per litre?

Convert whatever unit it’s given in (per gallon, per US gallon, per 5L, etc.) to a per-litre figure first — the calculator needs a consistent per-litre baseline to scale from.

Should I trust the calculator over my plants’ visible response?

No — use this as a starting point, then adjust based on how your plants actually respond (leaf color, growth rate, any nutrient burn or deficiency signs), since real growing conditions vary from any generic guideline.