A Practical Guide to Reading Your Iodine Bottle's Percentage Label

2%, 5%, 15%, 20% — what do these numbers actually mean for how much iodine is in a single drop? We walk through the math so the percentage on the label translates into something you can actually visualize.

What the Percentage Means

The percentage on an iodine bottle is a measure of concentration: how much iodine-containing material is dissolved in a given amount of liquid. A higher percentage means more iodine in every drop. It does not describe how many drops to take, how big the bottle is or how long it lasts.

The easiest way to think about it is in relative terms. A 5% solution has about two and a half times the iodine per drop of a 2% solution. A 10% solution has about twice as much as a 5% solution, and a 20% solution has about ten times as much as a 2% solution.

Why Drop Size Matters Too

A label percentage only turns into an amount per drop once you know how big a drop is. Glass droppers are designed to deliver a consistent drop, but drop size still varies a little between dropper designs, between liquids and with how the dropper is held. That is why reliable brands publish a drop-to-milligram reference for their own bottles instead of leaving customers to do the math. See our Lugol's iodine drop-to-milligram chart and why drop size varies between bottles.

Strengths Side by Side

• 2%: the lowest concentration. Popular with people who want fine control drop by drop.
• 5%: the most widely sold strength and the one most often referenced in older literature.
• 7% and 10%: fewer drops for the same amount of iodine compared with 2% or 5%.
• 15% and 20%: the most concentrated options, where each drop carries the most iodine.

Our side-by-side concentration chart shows how many drops of one strength match another.

Common Label Mistakes

• Comparing percentages across different product types. A 5% Lugol's iodine and a 5% product of another type may not deliver the same iodine per drop. Check the Supplement Facts panel for the actual amount per serving.
• Assuming a higher percentage is better. Concentration is about convenience and precision, not quality. The right strength is the one that matches the serving a person and their healthcare provider have settled on.
• Ignoring the serving size line. The Supplement Facts panel lists how much iodine is in one serving. That number, not the percentage, is what matters for daily intake. Our guide to reading a Supplement Facts panel walks through it.

Choosing a Strength

Lower strengths make small adjustments easy. Higher strengths mean fewer drops and a bottle that lasts longer at the same intake. Our Lugol's Solution comes in six strengths from 2% to 20%, and each strength has its own product page with the serving information printed on the label.

Frequently Asked Questions

Does a higher percentage mean a better product?
No. Percentage only describes concentration. Quality comes from purity, testing and packaging, which you can check on a Certificate of Analysis.

Should I talk to a doctor before starting?
Yes. Anyone considering a new supplement — especially one involving iodine — should check in with a healthcare provider first, particularly if pregnant, nursing, or managing a thyroid condition or thyroid medication.

Which strength percentage is right for me?
It depends on your goals and how concentrated a dose you're looking for — see 2% vs. 5% Lugol's Solution: Which Strength Do You Need? for a full breakdown.

Shop Lugol's Solution — the traditional, trusted way people have supported their iodine intake for over 200 years.

Lauren Mitchell covers comparisons, formats, and quality questions for the Iodine Journal.

This article is for general educational purposes only and has not been evaluated by the FDA. It is not intended to diagnose, treat, cure, or prevent any disease, and is not a substitute for advice from a qualified healthcare provider — especially if you are pregnant, nursing, taking thyroid medication, or managing a thyroid condition.