Mānuka Honey Ratings Explained: UMF, MGO, NPA, and KFactor
Four rating systems appear on Mānuka honey jars worldwide: UMF, MGO, NPA, and KFactor. Each measures something different. UMF is the most rigorous; KFactor is the least antibacterial-focused. This guide shows what each one measures and how to convert between them.
The four ratings at a glance
| Rating | Measures | Issued by | Used by |
|---|---|---|---|
| UMF | 4-marker certification (MGO, leptosperin, DHA, HMF) | UMF Honey Association (NZ) | Comvita, Manukora, NZ Honey Co., Kiva, Egmont, Happy Valley |
| MGO | Methylglyoxal content (mg/kg) | Independent labs (varies) | Manuka Health, Manuka Doctor, others |
| NPA | Non-peroxide antibacterial activity vs phenol | Laboratory measurement (not certification) | Used scientifically; rare on retail labels |
| KFactor | Pollen content + traceability + raw status | Wedderspoon (proprietary) | Wedderspoon |
What does UMF measure?
UMF is a four-marker certification administered by the UMF Honey Association in New Zealand. It tests methylglyoxal (MGO, antibacterial activity), leptosperin (Mānuka authenticity marker), dihydroxyacetone (DHA, freshness / maturity marker), and HMF (heat-damage / age marker). UMF certification is per-batch and traceable. Full detail at our UMF explainer.
What does MGO measure?
MGO is a single chemical measurement: methylglyoxal content in mg/kg of honey. It is the principal antibacterial compound in Mānuka. MGO labelling without UMF certification is legitimate (many brands do it) but only verifies one of UMF's four markers. Full detail at our MGO explainer.
What does NPA measure?
NPA (Non-Peroxide Activity) is the laboratory-measured antibacterial activity of Mānuka honey, indexed against a phenol reference solution. NPA 10 is roughly equivalent to a 10% phenol disinfectant. UMF is calibrated against NPA, so UMF 10+ ≈ NPA 10. NPA itself is rarely on retail labels but is the underlying biological property. Full detail at our NPA explainer.
What does KFactor measure?
KFactor is Wedderspoon's proprietary classification system. KFactor 16 indicates the honey is monofloral by Wedderspoon's pollen-counting standard, raw and unpasteurised, traceable from hive to home, sourced and packed in New Zealand, and free of antibiotics and pesticides. KFactor does not measure MGO content directly, so it is not directly comparable to UMF or MGO ratings. See our Wedderspoon review.
How do UMF, MGO, and NPA convert between each other?
| UMF | MGO (mg/kg) | NPA (approx) |
|---|---|---|
| 5+ | 83+ | 5 |
| 10+ | 263+ | 10 |
| 15+ | 514+ | 15 |
| 20+ | 829+ | 20 |
| 24+ | 1122+ | 24 |
Which rating should you trust most?
UMF is the most rigorous because it includes authenticity verification (leptosperin and DHA) alongside antibacterial activity (MGO). MGO alone is reliable but verifies less. NPA on its own is a chemistry measurement, not an authentication. KFactor verifies different attributes from UMF and is not directly comparable.
Common questions
Can a jar carry both UMF and MGO labels?
Yes, frequently. Most UMFHA-licensed brands publish both UMF and MGO numbers because the conversion is well-known and consumers shop on either.
Is KFactor the same as UMF?
No. They certify different things. UMF certifies antibacterial activity. KFactor certifies traceability and processing standards.
What does a Mānuka jar with no rating mean?
Either it is multifloral table-grade Mānuka with low antibacterial activity, or it has not been tested. Without a rating you cannot verify potency.