MGO and UMF are not two scores competing for the same crown. MGO measures a single compound, methylglyoxal, in milligrams per kilogram of honey. UMF is a licensed certification that measures methylglyoxal alongside three other markers, then layers independent auditing on top of all four. 

And neither number is what actually proves the honey in your hand is real Manuka. That comes from a New Zealand government test that most labels never even mention.

So here’s our guide to Manuka honey grading systems, so you can interpret any jar on the shelf.

MGO vs UMF: They Are Not Measuring the Same Thing

You could pick up two jars, see 400 on one and 15+ on the other, and assume they are looking at the same measurement in different units. They are not. One is a laboratory reading of a single compound. The other is a licensed certification that contains that reading, plus three more.

Knowing which is which is most of what you need to read a Manuka honey label properly, and it explains why two honeys with identical MGO figures can carry very different marks.

Four compounds do the work here: methylglyoxal, dihydroxyacetone, leptosperin, and hydroxymethylfurfural. Each has its place on the label for a different reason, and only one of them is the number brands tend to print largest. All four trace back to the nectar of Leptospermum scoparium, the wild Manuka plant that blooms across New Zealand for roughly four weeks a year, the same short window in which we harvest our own.

What Does MGO Mean in Manuka Honey?

MGO stands for methylglyoxal. The number beside it is a concentration in milligrams per kilogram, so MGO 830 means 830 milligrams of methylglyoxal in every kilogram of honey, the same reading our Creamed Mānuka Honey carries.

Methylglyoxal was identified as the dominant antibacterial constituent of New Zealand Manuka honey in 2008, at levels up to 100 times higher than those found in conventional honeys.

What most labels leave out is that methylglyoxal is not in the nectar to begin with. It forms slowly as the honey ripens, converting from dihydroxyacetone, the compound the Manuka flower actually produces. The figure on the jar is a snapshot of a slow, unhurried chemical process that keeps working long after the honey has left the hive.

A high MGO number tells you a honey is potent. On its own, it tells you nothing about where that honey came from.

What Does UMF Mean in Manuka Honey?

UMF stands for Unique Manuka Factor. It is a certification program run by the UMF Honey Association in New Zealand, and the mark is a licensed trademark rather than a description any producer can simply print.

The standard tests four markers, each for a different purpose: methylglyoxal for potency, leptosperin for authenticity, dihydroxyacetone for shelf life, and hydroxymethylfurfural for freshness. Leptosperin is the interesting one, because it occurs only in Manuka flower nectar and cannot be added to honey after the fact.

And UMF is a paid membership certification. Honey sold without the mark has not failed anything. It may simply come from a producer who has not licensed the trademark, which is the case with our own harvest at Mount Taranaki.

MGO to UMF Conversion: Reading a UMF Grade Down to Its MGO Floor

Because methylglyoxal is one of the four markers UMF tests, every UMF grade carries a published minimum MGO level. That makes the conversion possible in one direction. Here is what the UMF Honey Association publishes, in milligrams per kilogram.

Two things to take from this. The relationship is not linear, so doubling the UMF number does not double the MGO, and you cannot estimate a grade by multiplying. And the conversion only works in one direction. A UMF grade tells you a minimum MGO, but an MGO figure cannot tell you a UMF grade, because UMF also requires minimum leptosperin and DHA levels that methylglyoxal alone says nothing about. 

You can check this yourself. Our Creamed Mānuka Honey is independently tested at 830 mg/kg of MGO, just a shade over the UMF 20+ floor of 829.

Monofloral vs Multifloral Manuka Honey: The Word That Matters More Than Either Number

Before any grading number reaches a label, honey leaving New Zealand as Manuka has to pass a government test that has nothing to do with UMF or MGO.

The New Zealand Ministry for Primary Industries defines Manuka honey through five attributes: four chemicals from the nectar, plus one DNA marker from Manuka pollen. All honey labeled as Manuka for export must be tested against them by an MPI-recognized laboratory. The results decide whether a honey can be called monofloral or multifloral.

Monofloral means the honey came overwhelmingly from Manuka nectar, gathered by bees that worked almost nothing else. Multifloral means the bees worked Manuka alongside other flowers, and the marker levels come in lower. Both can legally say “Manuka” on the jar. But they are not the same product, and they should not cost the same.

This is an export requirement, so honey traded within New Zealand is not tested against it, though it must still be accurately labeled under the Fair Trading Act. If a jar does not say monofloral, find out why. Our own hives are helicoptered in, one by one, onto the remote, volcanic bushland at the base of Mount Taranaki, and left entirely alone until the bees have finished, which is how we can call ours monofloral with a straight face. Browse the Manuka collection with that question in mind.

Everything Else on the Label

Once you know what the numbers mean, the rest of the label reads quickly.

• Origin and packing. Look for where the honey was harvested and where it was packed. Honey packed at source, the way ours is, is easier to trace than honey shipped in bulk and jarred somewhere else entirely.

• Batch or lot number. This is the least glamorous thing on the jar and one of the most useful. Independent test certificates are issued per batch, so without a batch number there is nothing traceable to match a certificate to.

• The logo, not the letters. UMF is a licensed mark. The letters printed without the registered logo do not indicate certification.

• Other systems you may meet. NPA stands for non-peroxide activity and measures antibacterial strength against a phenol standard. K Factor is different again: K16 indicates monofloral Manuka and K12 multifloral, so it speaks to floral source rather than potency. The UMF Honey Association states that neither is calculated the way a UMF rating is. Various brand-owned systems also circulate. None of them convert cleanly into each other.

So Which MGO Should You Actually Buy?

Buy for how you plan to use it, not for the biggest number you can afford. Is a higher MGO always better? Only if you intend to eat it like medicine, a spoonful at a time.

Lower grades are table honey. Stir them into tea, spoon them over yogurt, bake with them, fold them into your daily rituals. You are buying flavor, sun-ripened and deeply nourishing, and the activity is a bonus you are not paying a premium for. 

Higher grades are for eating deliberately, a spoonful at a time, where the potency is the point and the price per gram reflects how little of it exists. Manuka blooms for roughly four weeks a year. Scarcity, not clever processing, is doing most of the work in that price.

Frequently Asked Questions

Does Manuka honey without a UMF logo mean it is fake?

No. UMF is a licensed certification, and some producers choose not to pay for the trademark. What matters is whether the honey has been independently tested and whether it meets the New Zealand definition of monofloral Manuka. Look for a test figure and a batch number rather than one particular logo.

Does Manuka honey lose potency over time?

Not necessarily. Because methylglyoxal forms from dihydroxyacetone after harvest, activity can hold steady or even rise as the honey matures. Heat and light, not time, are what cost you.

Is Australian Manuka honey the same as New Zealand Manuka honey?

Not quite. Australia holds most of the world’s known Leptospermum species, and Australian Leptospermum honey has been measured with methylglyoxal levels comparable to, and sometimes higher than, New Zealand Manuka. But UMF certification and the MPI monofloral definition are New Zealand systems. Australian honey will not carry either.

Can you cook with high-MGO Manuka honey?

You can, though it is an expensive way to sweeten something. Heat and long storage raise hydroxymethylfurfural, the marker used to judge whether honey has been overheated or kept too long. Save the high grades for eating raw or stirring into something already cooled, and bake with a wildflower honey instead.

Is a higher MGO number always better?

Not for every use. A higher MGO means more antibacterial potency, but it also means a higher price for a smaller jar, since the honey that produces it is rare. For everyday cooking or sweetening, a lower grade is the better, more abundant choice. Save the highest numbers for when potency itself is the point.

Next Steps

Everything above works on any jar, ours included, which is rather the point. We label with MGO because it is the number we can have independently measured and put in front of you without an intermediary standing in between. 

The honey behind it came from hives helicoptered, one by one, onto native bushland at the base of Mount Taranaki, harvested from a bloom that lasts about four weeks a year, and tested at 830 mg/kg. Traceable, impeccably sourced, and about as far from a marketing number as honey gets.

Explore our full Manuka collection for the complete Manuka ritual, powered by one of nature’s most extraordinary ingredients.