Comparing allicin in mg vs mcg comes down to one conversion: 1 mg equals 1,000 mcg, so a label reading 500 mcg is 0.5 mg. That single line does most of the work on any garlic label. Convert every product to the same unit per serving before you compare prices or doses. Most allicin comparison mistakes are just unit mismatches, not real differences between products.
Why allicin labels mix units
Milligrams suit bulk materials such as plant extracts at 400 to 600 mg per capsule. Micrograms suit trace compounds, where a milligram would be a huge dose. Both can appear in the same category, which is why one garlic product quotes the yield in mg while a garlic oil softgel quotes volatile sulphides in mcg. Neither unit is wrong. They describe different things at different scales.
The compound itself is unstable, formed when alliin meets the enzyme alliinase, so many labels state a calculated yield rather than a measured content figure. That's a calculated value from the alliin measured in the powder, and it deserves the skepticism you'd give any estimate.
Do the arithmetic once
Take two products. Product A: 600 mg aged garlic extract with a stated yield of 3.2 mg per capsule. Product B: garlic oil 5 mg, sulphur compounds 2,000 mcg per softgel. Convert B first: 2,000 mcg is 2 mg. Now both speak the same language, and A delivers more of what you're counting, at a serving of one capsule each.
Do this in the shop, not at home, while both labels are in front of you.
Write the conversion on the receipt if you keep notes. The 1,000 factor never changes, so it's worth 10 seconds per product and saves a wrong purchase. Over a year of buying, ten of these comparisons is maybe two hours of arithmetic, and the savings usually run past the cost of a bottle.
Per serving, not per capsule
Serving size is the second trap, and it catches more people than the conversion does. A label showing 250 mg per capsule with a serving of 4 capsules isn't a 250 mg product. Multiply before you compare, then divide by price and you get a cost per mg you can actually rank.
Watch the word "blend" as well. A 500 mg blend of four ingredients tells you nothing about the allicin fraction inside it, and no unit conversion rescues a missing number.
Older units that still show up
IU appears on older labels and describes biological activity rather than weight, mostly for vitamins A, D and E these days. You won't see it for allicin, but you'll see it on multi panels beside minerals quoted in mg, so the habit of converting before comparing covers the whole label, not one row.
The limit to keep in mind: unit comparisons assume the products measure the same compound. Allicin yield and total sulphur compounds are related but not identical, so a clean comparison needs the same marker on both labels. When the markers differ, treat the whole exercise as an estimate rather than a verdict.
A two minute label routine
Find the compound row, note the unit, convert to mg, multiply by servings per use, then divide by price. Write all three products on one line and the ranking is visible in seconds. Four steps, and the result is a single number per product.
That number settles the argument in the aisle, and it works across every supplement aisle, not just this one.
Frequently asked questions
What is the difference between mg and mcg?Show answerHide answer
A microgram is a thousandth of a milligram, so the number looks much larger.
Why do some labels use IU?Show answerHide answer
Older units like IU describe biological activity rather than weight.
How do I compare across units?Show answerHide answer
Convert to the same unit first, then compare per serving.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
