Short answer: MGO reports the measured concentration of methylglyoxal in Manuka honey, while NPA describes non-peroxide activity. They are related grading approaches, but they report different measurements and should be read exactly as stated on the product label.
MGO measures a compound
MGO is short for methylglyoxal. The figure is expressed in milligrams per kilogram and gives a direct concentration threshold. MGO 263+, for example, means the tested honey meets or exceeds 263 mg/kg of methylglyoxal.
NPA describes non-peroxide activity
NPA stands for non-peroxide activity. Honey can show activity related to naturally generated peroxide as well as non-peroxide factors. In laboratory descriptions, NPA is the activity remaining when peroxide effects are neutralised.
NPA is not the same as Total Activity, which can include peroxide and non-peroxide components. This distinction is especially useful when comparing Manuka and Jarrah terminology.
How to read a label showing both ratings
Some brands show MGO and NPA together to make their range easier to compare. Puspamrta MGO 500+, for example, is labelled NPA 15+. Read both as the declared grade for that jar rather than trying to calculate one rating yourself.
If two products use different systems, compare the seller's exact specifications and supporting product information. Avoid assuming that a similar-looking number has the same meaning across every grading scheme.
Which rating should you use when shopping?
For the Australian Honey Co. range, MGO is the simplest first filter because every Manuka product is organised by MGO strength. The corresponding NPA appears beside it for added clarity. After choosing a strength band, compare jar size, price, flavour position and availability.
Sources and further reading
Information notice: This article provides general food and product information, not medical advice. Honey is not suitable for infants under 12 months; see Healthdirect's infant safety information.