# Guaranteed analysis

> The guaranteed analysis is the legally required label statement of minimum nutrient content, giving P as P2O5 and K as K2O; multiply by 0.436 and 0.830 for elements.

- Canonical: https://genetixbay.com/knowledge/glossary/guaranteed-analysis.html
- Also written: guaranteed minimum analysis, label analysis, fertiliser label, oxide analysis
- 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"

The guaranteed analysis is the section of a fertiliser label listing the minimum percentage of each nutrient the manufacturer guarantees, by weight. By long convention, phosphorus is stated as P2O5 and potassium as K2O, a legacy of nineteenth-century analysis methods. Other nutrients (Ca, Mg, S, [micronutrients](https://genetixbay.com/knowledge/glossary/micronutrient.md)) are usually stated as elements, and the label may break nitrogen into [nitrate](https://genetixbay.com/knowledge/glossary/nitrate.md), ammoniacal and [urea](https://genetixbay.com/knowledge/glossary/urea.md) forms. Exact rules vary by jurisdiction.

## In practice

To compare products or build a recipe, convert to elements and to the final solution. A label showing [0-52-34](https://genetixbay.com/knowledge/glossary/monopotassium-phosphate.md) means 52% P2O5 and 34% K2O, which is about 22.7% P and 28.2% K. At 1 g/L, that gives about 227 mg/L (ppm) P and 282 mg/L K.

## Units and formula

| From | To element | Multiply by |
|---|---|---|
| P2O5 | P | 0.436 |
| K2O | K | 0.830 |
| P | P2O5 | 2.291 |
| K | K2O | 1.205 |

## Don't confuse with

- **Ingredient list**: names the salts or materials used, not their nutrient content.
- **N-P-K ratio**: the three headline numbers only.

## Related terms

[N-P-K ratio](https://genetixbay.com/knowledge/glossary/npk-ratio.md), [ppm of an element](https://genetixbay.com/knowledge/glossary/elemental-ppm.md), [Phosphorus](https://genetixbay.com/knowledge/glossary/phosphorus.md), [Potassium](https://genetixbay.com/knowledge/glossary/potassium.md), [Feed chart](https://genetixbay.com/knowledge/glossary/feed-chart.md)

## Read more

- [Hydroponic salts explained: what each fertiliser salt supplies](https://genetixbay.com/knowledge/nutrients/hydroponic-salts.md)
- [Buyer beware: potency labels, strain names and other claims that don't hold up](https://genetixbay.com/knowledge/basics/buyer-beware-label-claims.md)

## Sources

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