Curcumin, 95% curcuminoids
The highest percentage you will commonly see. 500 mg of a 95% extract is 475 mg of curcuminoids, so here the extract weight and the active amount are almost the same number.
How to Read a Standardisation Percentage on a Label
The number in brackets is usually more important than the number in front of it, and almost nobody reads it.
Quick answer
A standardisation percentage tells you how much of the compound an ingredient is studied for is actually in the extract. White mulberry extract 100 mg at 1% 1-deoxynojirimycin contains 1 mg of DNJ. Banaba extract 48 mg at 1% corosolic acid contains 0.48 mg of corosolic acid. Multiply the extract weight by the percentage to get the active amount, then compare that figure against the research rather than the headline milligrams.
What a standardisation percentage is
Plants are not consistent. Two batches of the same leaf, grown in different places or harvested in different weeks, contain different amounts of whatever it is people take the leaf for.
Standardisation is how a manufacturer removes that variation. The extract is processed and tested so that a fixed percentage of it is the compound of interest, and that percentage is printed on the label in brackets.
So white mulberry extract (leaf)(1% 1-deoxynojirimycin), 100 mg means two things: there is 100 mg of extract in a serving, and one percent of it, which is 1 mg, is DNJ.
That is good practice and a sign the manufacturer is buying to a specification. It also means the label has quietly handed you a second, smaller number, and the second number is the one the research is usually about.
The arithmetic, in three steps
Two minutes with a calculator will tell you more than an hour of reading the front of the bottle.
Find the extract weight
The number in milligrams beside the ingredient name. That is the weight of the extract, not of the active compound.
Find the percentage in brackets
It sits inside the ingredient name, usually right after the plant part. Something like (1% corosolic acid) or (10% ginsenosides) or (95% curcuminoids).
Multiply
Extract weight times the percentage. 48 mg at 1% is 0.48 mg. 100 mg at 1% is 1 mg. 500 mg at 95% is 475 mg. Now compare that answer against the dose in the research, not the number on the front of the bottle.
Three products can all say banaba extract on the front and deliver wildly different amounts of corosolic acid. The brackets are the only place that difference appears.
The same arithmetic, three ways
Two of these are from our own label. The third is an illustration of how much the percentage can change the answer.
| What the label says | Extract weight | Standardised to | Active compound in a serving |
|---|---|---|---|
| White Mulberry Extract (leaf)(1% 1-deoxynojirimycin) | 100 mg | 1% DNJ | 1 mg of DNJ |
| Banaba (Lagerstroemia speciosa) Extract (leaf)(1% corosolic acid) | 48 mg | 1% corosolic acid | 0.48 mg of corosolic acid |
| A hypothetical banaba at a higher standardisation | 48 mg | 18% corosolic acid | 8.6 mg of corosolic acid |
Same plant, same 48 mg, eighteen times the active compound. This is why comparing two botanical products on extract weight alone is close to meaningless.
About the product behind this blog
GlucoGold Advanced is a once-daily blood sugar tablet: 1,000 mg of berberine, 250 mg of OEA, 200 mcg of chromium and three botanicals, with every amount printed and no proprietary blend. We publish the missing price as plainly as the doses.
Order NowRead the label firstWhat it means when there is no percentage at all
Plenty of labels give an extract weight and no standardisation. That is not automatically bad and it does change what you can conclude.
Without a percentage you cannot tell whether the extract is concentrated or barely processed. A 10:1 extract and a 1:1 extract can both be described as an extract, and one is ten times the plant material of the other.
Some labels give a ratio instead, written as 10:1 or 20:1. That tells you how much raw plant went in per unit of extract, which is useful for comparing extracts of the same plant and useless for comparing across plants.
The one thing that should raise an eyebrow is a label that names a compound on the front of the bottle and gives neither a percentage nor a ratio on the back. If corosolic acid is the selling point, the amount of corosolic acid should be knowable.
Running the check on our own label
GlucoGold Advanced gives two standardisation percentages and four plain amounts, so the check is quick.
Mulberry at 100 mg and 1% DNJ gives 1 mg of DNJ. Banaba at 48 mg and 1% corosolic acid gives 0.48 mg. Berberine at 1,000 mg is the compound itself rather than an extract weight, so it needs no conversion. Chromium at 200 mcg is elemental chromium. OEA at 250 mg is the compound. Cinnamon at 75 mg is an extract with no percentage given, which is a small gap on an otherwise unusually clear label.
Run that against the research and one row stands out. The 2022 trial we cite used 500 mg of banaba twice a day. This label has 48 mg once a day, which is roughly a twentieth of it, and standardisation does not rescue that number.
We publish that on the home page, in the dosage chart and in the table beneath it. A label that lets you do this arithmetic is a better label than one that does not, and the arithmetic still has to be done.
The two-minute version
Extract weight times the bracketed percentage equals the amount that matters. Do it for the two ingredients the front of the bottle is selling you. If the percentage is missing and the compound is named on the front, that is the gap to ask about.
Standardisation percentages you will meet often
Five that turn up across the supplement aisle, and what the bracketed compound actually is.
Green tea, 50% EGCG
Halfway. 200 mg of extract gives 100 mg of EGCG. This is also the family where the percentage carries a safety implication rather than only an efficacy one.
Banaba, 1% corosolic acid
At the other end. 48 mg of extract gives 0.48 mg of the compound, which is why a banaba number on a front label tells you almost nothing on its own.
Mulberry, 1% DNJ
Same arithmetic. 100 mg gives 1 mg of 1-deoxynojirimycin, and the research on mulberry is about the DNJ rather than the leaf.
Ginseng, 5% ginsenosides
A common middle figure. 300 mg of extract gives 15 mg of ginsenosides, and products vary from 3% to 20% for the same herb.
No percentage at all
The most common case, and the one where you simply cannot do the arithmetic. Look for an extract ratio instead, and if neither is given, treat the front-of-bottle claim as a name rather than a dose.
Is a low percentage always bad?
No, and this is where a useful check turns into a blunt instrument if you are not careful.
A low standardisation can mean a gentler extraction that keeps more of the plant's other compounds, which some manufacturers argue for on purpose. It can also mean the cheapest material on the market. From outside the company you cannot tell which.
What you can do is compare like with like. Two banaba products at 1% and 18% are not comparable on extract weight, and the one at 18% is delivering eighteen times the compound the research is about.
And you can compare against the trial. If a study used 500 mg twice daily of an extract at a stated percentage, and the product in your hand has a twentieth of that, the gap is real whatever the extraction philosophy behind it.
The two-minute version
Extract weight times the bracketed percentage equals the amount that matters. Do it for the two ingredients the front of the bottle is selling you, and compare the answer against the research rather than the headline milligrams.
Extract ratios are a different number entirely
Alongside percentages you will meet ratios, written as 4:1, 10:1 or 20:1. They answer a different question and the two get confused constantly.
A ratio tells you how much raw plant went in for each unit of extract that came out. A 10:1 extract means ten kilograms of leaf produced one kilogram of extract, so 100 mg of it stands in for roughly 1,000 mg of the raw material.
A percentage tells you what the extract contains. A ratio tells you what it was made from. A good label gives you the percentage, because that is the number research doses are expressed in. A ratio is better than nothing and it is not the same information.
Where a ratio genuinely helps is comparing two extracts of the same plant from the same kind of process. Where it misleads is across plants, because a 20:1 extract of a weak herb and a 4:1 extract of a strong one tell you nothing about each other.