Pick up a jar of manuka honey and you’ll see numbers that look like a code: MGO 250+, UMF 10+, sometimes a “KFactor” or a bare “20+.” These grades are supposed to tell you how potent the honey is — but they also drive prices from reasonable to absurd. Here’s what the numbers actually mean, how the two main scales compare, and which grade is genuinely worth buying.
Quick answer: MGO measures the milligrams of methylglyoxal (manuka’s active antibacterial compound) per kilogram of honey — higher means stronger antibacterial activity. UMF is a broader quality-and-potency grading that also verifies authenticity. The two scales roughly correspond. For most people, a mid-range grade is plenty; sky-high numbers are largely a premium you don’t need unless you’re using it therapeutically. For the honey itself, see our manuka honey guide.
Why manuka gets a rating at all
Ordinary honey doesn’t come with a potency score. Manuka does because its value rests on one measurable thing: methylglyoxal (MGO), the compound responsible for its unusual, non-peroxide antibacterial activity. Researchers identified MGO as the dominant antibacterial constituent of manuka honey, found at levels up to 100 times higher than in regular honey.1
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Explore new cuisinesBecause MGO is measurable, manuka can be graded — and because it’s what you’re paying extra for, the grade is what the price tracks. The rest of this guide is really about reading those numbers without overpaying.
MGO: the direct measure
MGO (sometimes written MG or MGO™) tells you the milligrams of methylglyoxal per kilogram of honey. It’s a direct chemical measurement, so it’s refreshingly literal: MGO 250 means 250 mg/kg of methylglyoxal.
- Higher MGO = more antibacterial punch.
- Common grades run from around MGO 30 up to MGO 800+ (and rare, very expensive jars go higher).
- It’s the number that most transparently reflects the active compound.
UMF: the broader standard
UMF (Unique Manuka Factor) is a grading and certification system that does more than measure one compound. A UMF rating reflects antibacterial potency and verifies key markers of genuine manuka honey, so it doubles as an authenticity check. UMF-licensed jars are independently tested.
UMF numbers are smaller (a different scale), which confuses people — a UMF 10 is not “weaker” than an MGO 250; they’re just different units measuring related things.
How the two scales compare
The scales roughly line up. As an approximate guide:
| UMF | ≈ MGO (mg/kg) | Typical use |
|---|---|---|
| 5+ | ~83 | Everyday eating, mild |
| 10+ | ~263 | General use, throat soothing |
| 15+ | ~514 | Stronger, therapeutic-leaning |
| 20+ | ~829 | High potency, premium |
Treat these as ballpark conversions, not exact — brands and testing vary. The key point: a UMF number and an MGO number can describe the same jar.
Which grade should you actually buy?
Here’s where you can save real money:
- For everyday eating or a soothing throat/cough: a low-to-mid grade (roughly MGO 100–250 / UMF 5–10) is plenty. You’re getting genuine manuka without the extreme markup, and for general use the antibacterial number barely matters — see manuka honey for what it’s realistically good for.
- For wound or skin applications: a higher grade makes more sense, and ideally you’d use a medical-grade manuka product rather than a food jar.
- Chasing the highest number “to be safe”: usually a waste. There’s no evidence that eating ultra-high-MGO honey does anything special internally; you’re paying a steep premium for a bigger number on the label.
Watch for marketing tricks
- Bare “20+” or “K-Factor” or “Active” with no MGO/UMF: these unregulated labels don’t reliably tell you the methylglyoxal content. Look for an actual MGO number or a UMF certification.
- Total activity vs non-peroxide activity: cheaper “active” honeys may be quoting ordinary peroxide activity, not manuka’s signature MGO. MGO/UMF are the numbers that matter.
- Authenticity: manuka is expensive enough to attract fakes. A UMF license or a stated MGO value from a reputable brand is your best safeguard.
Is high-MGO honey safe to eat?
Methylglyoxal is a reactive compound, and some people worry that high-MGO honey might be harmful. For normal food amounts, that concern isn’t supported — manuka honey has a long history of safe use, and the MGO doses you get from eating it are small. There’s no established safety reason to avoid higher grades; the better argument against them is simply cost, since eating ultra-high-MGO honey has no proven internal advantage over a modest grade. As with all honey, the real limits are its sugar content and the absolute rule against giving it to infants under 12 months.
Suggested read: Manuka Honey: Benefits and Uses, Backed by Science
The bottom line
MGO and UMF are two ways of grading the same thing — manuka honey’s methylglyoxal-driven antibacterial strength. MGO gives you the direct milligrams-per-kilogram; UMF adds an authenticity-verified certification. They correspond roughly, so don’t be thrown that the numbers look so different.
The practical takeaway: for eating or a sore throat, a modest grade is all you need, and the highest numbers are mostly a premium without a proven internal payoff. Reserve the strong grades (or medical-grade products) for wound and skin use, and always look for a real MGO figure or UMF license so you’re not buying marketing. For everything else manuka can and can’t do, see our manuka honey guide — or compare it to everyday raw honey.
