# ppm of an element

> Ppm of an element means milligrams of that element per litre of solution (mg/L), the unit nutrient recipes use; it is not the ppm shown on an EC meter.

- Canonical: https://genetixbay.com/knowledge/glossary/elemental-ppm.html
- Also written: elemental ppm, mg/L of an element, ppm N, ppm per element, parts per million (nutrient)
- Glossary category: Nutrients · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

In nutrient recipes, "ppm" of an element means parts per million by mass, which in water equals milligrams of that element per litre (mg/L). "150 ppm N" means 150 mg of nitrogen per litre, whatever salt it came from. Research papers often use mmol/L instead.

## In practice

A recipe written in elemental ppm lets growers compare feeds and build their own. To find how much of a salt delivers a target, use its percentage: 1 g/L of a salt supplies (percent × 10) mg/L of each element. [Calcium nitrate](https://genetixbay.com/knowledge/glossary/calcium-nitrate.md) at 19% Ca gives 190 ppm Ca per g/L, so 150 ppm Ca needs about 0.79 g/L.

## Units and formula

- mg/L of element = g/L of salt × element % × 10
- mmol/L × atomic mass = mg/L (N 14.0, P 31.0, K 39.1, Ca 40.1, Mg 24.3, S 32.1)

## Don't confuse with

- **EC meter ppm (ppm500 / ppm700)**: an estimate of total dissolved salts converted from [electrical conductivity](https://genetixbay.com/knowledge/glossary/ec.md), not a count of any element. 1.0 [mS/cm](https://genetixbay.com/knowledge/glossary/ms-cm.md) reads about 500 or 700 "ppm" depending on scale.
- **Oxide ppm**: some charts quote P2O5 or K2O instead of P or K; convert first.

## Related terms

[Per-element dosing](https://genetixbay.com/knowledge/glossary/per-element-dosing.md), [Guaranteed analysis](https://genetixbay.com/knowledge/glossary/guaranteed-analysis.md), [Stock solution](https://genetixbay.com/knowledge/glossary/stock-solution.md), [Feed chart](https://genetixbay.com/knowledge/glossary/feed-chart.md)

## Read more

- [EC vs PPM: the 500 and 700 scales, CF, and how to convert](https://genetixbay.com/knowledge/ph-ec/ec-ppm-scales.md)
- [Hydroponic salts explained: what each fertiliser salt supplies](https://genetixbay.com/knowledge/nutrients/hydroponic-salts.md)

## Sources

1. Sonneveld C, Voogt W. 2009. Plant Nutrition of Greenhouse Crops. Springer. https://doi.org/10.1007/978-90-481-2532-6