MGO vs UMF vs MGS: The Mānuka Grading Systems Explained

Walk into any premium grocery store and you'll see Mānuka honey jars marked with three different rating systems: MGO, UMF, and sometimes MGS. Three numbers. Three logos. Three claims of authenticity. And no consistent shelf-talker explaining the difference.

For a buyer making a NZ$50–$300 purchase decision, this is confusing. For a distributor evaluating suppliers across markets, it's worse — your retail partners in the UAE, India, China, and the UK each ask the question differently and expect different answers.

This guide does three things:

1. Explains what each grading system actually measures
2. Provides the official UMFHA UMF↔MGO conversion table — verified directly from the UMF Honey Association
3. Tells you which rating system to look for depending on where you're buying or selling

No spin. All sources linked at the end.

What MGO actually measures

MGO stands for Methylglyoxal. It's a naturally occurring organic compound found in unusually high concentrations in Mānuka honey compared with other monofloral honeys. Methylglyoxal is what gives genuine Mānuka its distinctive non-peroxide antibacterial activity — the property that has made it the subject of more than 500 published research papers since the 1980s.^[1]

MGO is measured directly. The unit is milligrams per kilogram (mg/kg) of honey. A jar marked MGO 263+ contains at least 263 mg of methylglyoxal per kilogram of honey. A jar marked MGO 829+ contains at least 829 mg/kg.

The "+" is important. It's a minimum guarantee — the actual concentration can be higher.

What MGO doesn't measure: authenticity. A high MGO number on its own doesn't prove the honey came from Leptospermum scoparium (the New Zealand Mānuka plant). It only proves the honey contains methylglyoxal. There have been documented cases of producers adding synthetic MGO to ordinary honey to fake high grades — including a 2019 New Zealand prosecution where a company was fined NZ$372,500 for exactly this.^[2]

That's why the second system exists.

What UMF actually measures

UMF stands for Unique Mānuka Factor, a grading and authenticity standard run by the Unique Mānuka Factor Honey Association (UMFHA) based in Auckland. UMF is the most rigorous Mānuka grading system because it doesn't rely on a single number — it tests four separate compounds and requires all four to pass minimum thresholds.^[3]

The four UMF markers and what each one verifies:

• MGO (Methylglyoxal) — Potency: the antibacterial-active compound
• Leptosperin — Authenticity: a chemical signature unique to Leptospermum nectar
• DHA (Dihydroxyacetone) — Shelf life: the precursor compound that converts to MGO over time
• HMF (Hydroxymethylfurfural) — Freshness: must be below a maximum threshold or the honey has been overheated or stored too long

A UMF licensee must publish all four results for every batch. A jar carrying the UMF logo with a number (e.g. UMF 15+) has passed all four tests at the corresponding threshold.

Why this matters: a producer can fake MGO. They cannot fake all four markers. Leptosperin in particular is a chemical signature only produced by genuine Mānuka nectar — it's the compound that catches synthetic adulteration.

The official UMFHA UMF ↔ MGO conversion table

This is the verified table from the UMF Honey Association.^[3]

Important caveat from UMFHA: "MGO does not convert to UMF." A jar can have a high MGO number and still fail to qualify for a UMF rating if it doesn't pass the Leptosperin, DHA, or HMF thresholds. The table above shows the MGO floor for each UMF grade — not a strict equivalence.

In practice, the conversion is asymmetric:

• UMF → MGO: straightforward (UMF 10+ ≥ MGO 261 mg/kg)
• MGO → UMF: uncertain (MGO 263+ on its own can't be assumed to be UMF 10+ unless the other three markers also pass)

If you're shopping or sourcing, always check whether the jar carries the UMF logo specifically — not just an MGO number alone.

What MGS actually measures

MGS stands for Molan Gold Standard, named after the late Dr Peter Molan — the University of Waikato researcher who first identified Mānuka's antibacterial activity in the 1980s. MGS was an early grading system based on Dr Molan's research methodology, predating UMF in some markets.

In practice, MGS-marked Mānuka is increasingly rare on global shelves. The major Mānuka brands now use either UMF (UMFHA-certified) or MGO labelling. MGS still appears on some smaller-batch products, particularly those positioned around Dr Molan's research heritage.

Practical guidance: if you see MGS, treat it as a single-factor grade closer to MGO than to UMF — it doesn't typically include the four-marker authenticity test that UMF requires. Ask the producer for the full lab certificate.

Which system should I look for as a buyer?

It depends on the market and the use case.

For consumers buying for personal use

• MGO is fine if you trust the brand. The number is straightforward and meaningful.
• UMF is the safer choice. The four-marker test catches adulteration that pure MGO testing misses.

For retailers stocking Mānuka

• Stock UMF-rated product if your customers are educated. UMF licensees are searchable on the UMFHA register, which is a defensible marketing position.
• MGO is acceptable for entry-tier and broad retail where price sensitivity matters more than premium positioning.
• Avoid generic "Mānuka blend" or "with Mānuka" labelling. Both fail the basic regulatory test in major markets.

For distributors and importers

• Always ask for the MPI 5-attribute test certificate, not just an MGO number. MPI certification is mandatory for honey exported from New Zealand as Mānuka, and it's a stronger authenticity signal than either MGO or UMF in isolation.^[4]
• For markets with educated buyers (UK, Germany, Singapore), UMF licensing carries weight.
• For markets where MGO is the dominant convention (UAE, parts of Asia), high-MGO labelling is acceptable as long as MPI certification backs it.

Which system does Nuka use?

Nuka publishes MGO ratings on every jar — verified by independent batch testing — and provides MPI 5-attribute test certificates with every commercial order. We also offer UMF-equivalent grade information on request for distributors operating in UMF-led markets.

The reason we lead with MGO: it's the cleanest, most internationally legible measurement. MGO 263+ means the same thing in Auckland, Mumbai, Dubai, and London. UMF requires explanation in markets where consumers haven't been educated on it.

For any partner, we provide all four UMF compound results on request — Leptosperin, DHA, HMF, and MGO — even when the jar is sold under MGO labelling.

Quick reference: what to look for on the label

1. A specific number — "MGO 263+" or "UMF 10+", not "Mānuka blend" or "with Mānuka"
2. The MGO or UMF logo — not a generic word
3. Country of origin: New Zealand — Australian Mānuka is a different plant species
4. MPI 5-attribute test certificate — available on request from any legitimate NZ Mānuka producer
5. Batch number traceability — a real producer can link a jar back to a specific harvest batch and lab certificate

Common questions

Is UMF 10+ the same as MGO 263+?

The MGO floor for UMF 10+ is 261 mg/kg, so the answer is "approximately yes, on the MGO axis alone." But a UMF 10+ jar must also pass Leptosperin, DHA, and HMF thresholds — so UMF is the stricter rating.

Can MGO be faked?

Yes — there's a documented New Zealand case from 2019 where MGO was synthetically added to ordinary honey. UMF testing is harder to fake because it tests four compounds simultaneously, including Leptosperin which only appears in genuine Mānuka nectar.

What's the highest grade available?

UMF 25+ corresponds to MGO ≥ 1197 mg/kg. Some Mānuka honeys reach MGO 1700+ or higher, but volumes are very limited. Genuine ultra-high-grade Mānuka is rare because the conditions that produce it (specific climate stress, high-MGO-producing tree variants) don't occur every season.

Which grade is "best"?

There's no universal "best." Higher MGO is more expensive but isn't necessarily better for every use. Daily use typically calls for MGO 263+ to MGO 514+. Targeted therapeutic use (where MGO concentration matters) calls for higher grades. Premium gifting and ultra-luxury markets call for MGO 1200+ or UMF 20+.

How to verify any Mānuka jar in 60 seconds

If a jar carries a UMF rating, look up the licensee on the UMFHA register at umf.org.nz. You'll see the company name, the license number, and the products covered.

If a jar carries an MGO rating only, ask the producer (or your supplier) for:

• The independent MGO test certificate for that batch
• The MPI 5-attribute test result for that batch
• The Certificate of Origin

A real Mānuka producer has these ready within hours. A fraudulent one will deflect.

At Nuka, every jar is independently tested and traceable to a specific batch via our batch lookup tool. For wholesale buyers, we share the full documentation pack — MGO, UMF compound results, MPI certificate, and Certificate of Origin — with every commercial order.

The takeaway

• MGO measures one thing (methylglyoxal). It's clear and globally legible.
• UMF measures four things (MGO + Leptosperin + DHA + HMF). It's stricter and harder to fake.
• MGS is a legacy single-factor grade — increasingly rare on shelves.
• MPI certification sits underneath all of these — it's the regulatory foundation that legitimises any Mānuka honey for export from New Zealand.

If you're buying: look for a specific number from one of these systems, plus NZ origin, plus batch documentation. If you're stocking or distributing: demand the MPI certificate alongside whichever grading system your market expects.

If a product can't show you the documentation, it's not Mānuka by any standard worth buying.

Sources

1. Mavric, E. et al. (2008). "Identification and quantification of methylglyoxal as the dominant antibacterial constituent of Mānuka (Leptospermum scoparium) honeys from New Zealand." Molecular Nutrition & Food Research. Foundational MGO research, summarised on UMFHA at umf.org.nz/nz-manuka-honey
2. "Fines totalling $372,500 imposed in landmark mānuka honey fraud case." Ministry for Primary Industries (NZ Government). View →
3. "UMF Certification Comparison" — Unique Mānuka Factor Honey Association official grading table (Leptosperin, DHA, MGO, HMF thresholds). View →
4. "Ensuring Mānuka honey is authentic" — MPI scientific definition and 5-attribute test for export. View →