Can You Calculate Sulforaphane From Glucoraphanin? Why Simple Label Maths Breaks Down

You have three supplement labels open and a phone calculator in hand.

• Label A: 1,200 mg broccoli sprout powder
• Label B: 30 mg glucoraphanin
• Label C: 6 mg minimum sulforaphane

At first glance, the biggest number looks strongest. Then the calculator comes out: perhaps 30 mg of glucoraphanin can be converted into a sulforaphane figure, and perhaps that result can be compared with 1,200 mg of powder or a 6 mg minimum.

But the arithmetic is not the first problem. The first problem is identifying what each number measures. One is total plant material, one is a precursor, and one is a finished-product sulforaphane statement. They sit at different stages of the product and cannot be compared as though they are three versions of the same dose.

You Can Calculate a Ceiling, Not the Real Result

A theoretical sulforaphane maximum can be calculated only when the exact glucoraphanin chemical form, purity and molar quantity are known. An actual amount formed or absorbed cannot be calculated from a glucoraphanin milligram figure alone because enzyme activity, competing reaction products, formulation, digestion and individual metabolism affect the result.

Glucoraphanin is a precursor. Sulforaphane is one possible product formed when glucoraphanin is hydrolysed, commonly with help from the enzyme myrosinase. In the idealised chemical relationship, one molecule of glucoraphanin can produce one molecule of sulforaphane.

That relationship is one-to-one in moles, not milligrams. Molecules with different molecular masses do not weigh the same, even when the molecule count is equal. A theoretical maximum therefore requires a molar calculation. It is not a finished-product yield, an absorbed dose, or a predicted health result.

The Paper-Only Equation

The reference molecular formula for free glucoraphanin is C₁₂H₂₃NO₁₀S₃, with an average molecular mass of approximately 437.493. Sulforaphane has the formula C₆H₁₁NOS₂ and a molecular weight of 177.29.^{1, 2}

This is the limit of any glucoraphanin mg to sulforaphane mg calculation: a theoretical sulforaphane yield under tightly defined assumptions. It assumes pure free glucoraphanin, complete one-to-one conversion, and no competing reaction products. It does not predict finished-product yield. It does not predict human absorption. It is not dosing advice.

A potassium salt or another chemical form changes the molecular mass. That changes the milligram ratio even though the underlying one-to-one molar relationship may still be used for a theoretical reaction. If the label does not identify the chemical form and purity, there is no responsible milligram calculator to apply.

Five Assumption Locks That Break the Calculator

Lock 1: The number may be plant or extract weight

A label showing 1,000 mg of broccoli sprout powder is stating the weight of the plant material in the serving. It is not saying that the serving contains 1,000 mg of glucoraphanin. Plant powders contain many compounds, including fibre, protein, carbohydrates, minerals, moisture and numerous phytochemicals.

The same issue applies to total extract weight. A 400 mg broccoli extract might contain a quantified amount of glucoraphanin, but the whole 400 mg is not glucoraphanin unless the label and specification explicitly say so.

Lock 2: Chemical form and purity may be unspecified

Pure free glucoraphanin, a glucoraphanin potassium salt, a standardised botanical extract and a mixed broccoli ingredient do not share the same mass basis. A label might state the mass of the whole ingredient, the mass of an active marker within that ingredient, or an equivalent amount calculated from a source material.

Without the chemical form, purity and basis of the claim, a milligram-to-milligram equation can quietly compare different things.

Lock 3: Myrosinase presence is not the same as tested activity

Myrosinase is central to conversion, but simply seeing the word myrosinase on a label does not prove how much active enzyme remains in the finished product. Source material, drying, heat, moisture, storage, capsule design and the digestive environment can all affect enzyme performance.

A useful label distinction is whether the brand merely lists a myrosinase-containing ingredient or states that activity has been tested in the finished formulation. Even then, active myrosinase does not guarantee complete conversion in every capsule or every person.

Lock 4: The reaction may produce more than sulforaphane

Glucoraphanin hydrolysis does not automatically send every precursor molecule to the same desired end compound. Depending on the plant matrix, reaction conditions and associated proteins, breakdown can produce sulforaphane, sulforaphane nitrile and related products.³

That is why a theoretical one-to-one pathway should not be presented as proof that all converted precursor becomes sulforaphane.

Lock 5: Product formation and human recovery are different

Several stages are often collapsed into one vague idea of conversion:

• Formation: how much sulforaphane forms in the product or digestive matrix
• Absorption: how much enters the body from the digestive tract
• Metabolism: how sulforaphane is transformed into conjugated metabolites
• Urinary recovery: how much of those measured metabolites appears in collected urine

These measurements can be related, but they are not interchangeable. A label yield, a blood concentration and a urinary metabolite percentage answer different questions.

Human-Study Reality Check: The Same 50 mg Precursor, Different Measured Output

A 2026 randomised, double-blind crossover study by Mastaloudis and colleagues shows why the glucoraphanin number alone cannot settle the comparison.³

Sixteen adults received two defined interventions on separate occasions. Both contained 50 mg, or 115 micromoles, of glucoraphanin from broccoli seed extract. One intervention also supplied mustard-seed myrosinase. The other relied more heavily on microbial conversion.

Average bioavailability based on urinary sulforaphane metabolites was 39.8 percent with supplied myrosinase and 18.6 percent without it. During the first eight hours, measured conversion was 25.4 percent versus 8.0 percent.

The identical 50 mg glucoraphanin number did not produce identical measured recovery. The formulation and route of conversion mattered.

These results need firm boundaries. The trial used a defined broccoli seed extract, mustard-seed powder and ascorbic acid formulation. It was not a study of Kiwi Superfoods Broccoli Sprout Powder. The percentages are not universal conversion factors, and they should not be converted into a simplistic label milligram figure for another product.

Why No Generic Conversion Percentage Works

Earlier human research also found wide differences across preparations and people. Fahey and colleagues reported that glucoraphanin conversion without active plant myrosinase had ranged from approximately 1 to 40 percent among participants in cited work. Several preparations without active myrosinase averaged around 10 percent, while several preparations retaining active myrosinase produced averages around 35 to 40 percent.⁴

Those are study-specific observations, not a conversion table for the supplement aisle. There is no single glucoraphanin conversion rate that can be applied across products. The preparation, enzyme activity, delivery matrix and individual gut microbiota all influence the measured result. An average from one research product cannot be pasted onto a different powder, extract or capsule.

A Hierarchy of Label Numbers

When shoppers compare a broccoli extract label, it helps to place the number at the correct level. This hierarchy moves from the furthest upstream input to the closest measured human output:

1. Raw broccoli or sprout-material weight
2. Total extract weight
3. Quantified glucoraphanin
4. Theoretical sulforaphane potential
5. Tested finished-product minimum or yield
6. Measured human sulforaphane metabolites

A larger number higher in the hierarchy is not necessarily more informative. A 1,200 mg plant-material figure can be perfectly accurate while still saying less about sulforaphane output than a smaller, clearly defined finished-product minimum.

A number nearer the bottom may answer a more useful question, but it also needs context. Was the finished-product figure theoretical or tested? Was the human measurement taken from urine, plasma or another matrix? Was it an average across a study group or an individual result?

No number in this hierarchy guarantees a health outcome.

Evidence Wording Decoder

Real supplement labels use varied terms. The NIH Dietary Supplement Label Database records related wording including sulforaphane, sulforaphane glucosinolate, standardised amounts and sulforaphane potential.⁵ The database catalogues information printed on manufacturer and marketer labels. It is useful for seeing how terminology is used, but it does not independently verify every product or establish one universal definition for each marketing phrase.⁶

Label wording	Practical meaning	What it does not prove
Contains	An ingredient or compound is stated as present.	Its activity, conversion or absorption.
Standardised to	The ingredient is manufactured to meet a stated marker level or range.	One universal test method or guaranteed human exposure.
Equivalent to	A stated relationship to a source material, fresh weight or another basis.	That the equivalent number is the active compound amount.
Sulforaphane potential	A claimed amount that may be formed under the brand's defined assumptions or method.	A universal global definition, complete conversion or absorbed sulforaphane.
Guaranteed minimum	The brand commits that the stated product specification will not fall below a defined amount under its stated basis.	The amount every person absorbs or recovers as metabolites.
Measured yield	A result obtained under a specified analytical or conversion procedure.	That the same yield occurs in every digestive system.
Bioavailability	The proportion made available to the body, defined by the study's measurement method.	A universal product conversion rate or guaranteed health effect.

Some labels may also present sulforaphane equivalents, which still require a clear basis and method. For any of these terms, including an active myrosinase label claim, look for the brand's explanation of how the number was established, what serving it applies to, and whether the figure is theoretical, product-tested or measured in humans. That context is essential when you compare sulforaphane supplement labels.

Why We State a Minimum Sulforaphane Yield, Not Just a Broccoli Weight

Our current product page describes Kiwi Superfoods Broccoli Sprout Powder as 100 percent NZ-grown, lightly milled broccoli sprouts. The sprouts are air-dried with the intention of preserving active myrosinase. The page states guaranteed glucoraphanin and active myrosinase, with independent testing for glucoraphanin levels and myrosinase activity.⁷

The daily serve is two 600 mg capsules, or 1,200 mg of sprout powder in total. The page says this represents approximately 12 g of fresh broccoli sprouts and supplies a guaranteed minimum of 6 mg sulforaphane per daily dose.

That 6 mg statement is a finished-product minimum supplied by Kiwi Superfoods. It is not a claim that every person absorbs 6 mg. It is not a urinary-metabolite result, a clinical-trial equivalence, or a number created by multiplying 1,200 mg of powder by a generic conversion percentage.

It also does not reveal the product's exact glucoraphanin amount, prove complete conversion, or guarantee a health outcome. The live page does not visibly publish the precise glucoraphanin quantity, chemical salt form, assay methodology, or calculation used to establish the minimum. We will not invent or reverse-engineer those details.

The practical value is the boundary itself: total broccoli weight describes the input, while the stated minimum addresses finished-product sulforaphane yield on the brand's specification basis. Human absorption remains a separate question.

The Five-Question Reverse-Engineering Test

Before comparing two label numbers, ask only these five questions:

1. What exactly is the number measuring?
2. Is the amount per capsule or per complete daily serve?
3. Is glucoraphanin quantified separately from the total extract?
4. Is active myrosinase present and tested?
5. Is the sulforaphane figure theoretical, product-tested or measured in humans?

If a label cannot answer the first question, the calculator should stay closed.

Calculation Red Flags

Do not:

• Multiply total broccoli powder weight by a generic conversion percentage
• Compare milligrams with micromoles without converting units
• Treat sulforaphane potential as absorbed sulforaphane
• Apply the 18.6 percent, 39.8 percent or another study result to an unrelated product
• Increase your serving because a home calculation produced a low number
• Assume more precursor automatically produces more human exposure

Follow the product label rather than a home-derived dose. Check with a qualified health professional before using concentrated broccoli sprout supplements during pregnancy or breastfeeding, for children, before planned surgery, or if you have a thyroid condition, complex health condition or take regular medicines.

FAQs

Can you calculate sulforaphane from glucoraphanin?

You can calculate a theoretical ceiling only when the exact glucoraphanin form, purity and molar amount are known. You cannot calculate actual product yield or human absorption from a glucoraphanin milligram figure alone.

Is glucoraphanin converted to sulforaphane at a one-to-one ratio?

The idealised reaction is one molecule of glucoraphanin to one molecule of sulforaphane, so it is one-to-one in moles. It is not one-to-one in milligrams because the molecules have different masses.

How much sulforaphane can 10 mg of glucoraphanin theoretically make?

Using pure free glucoraphanin at approximately 437.493 molecular mass and sulforaphane at 177.29, the theoretical ceiling is about 4.05 mg. This is not a prediction of product yield, absorption or an appropriate dose.

Why does 10 mg of glucoraphanin not become 10 mg of sulforaphane?

Equal molecule counts do not mean equal weights. Sulforaphane has a lower molecular mass than glucoraphanin, and real conversion can also be incomplete or directed towards other breakdown products.

What does sulforaphane potential mean on a supplement label?

It generally refers to an amount that may be formed under the brand's stated assumptions or method. The phrase has no single universal definition, so check how the brand established the number.

Is broccoli extract weight the same as glucoraphanin weight?

No. Extract or powder weight includes the full ingredient matrix. Glucoraphanin is only one component unless it is separately quantified.

Does the potassium salt form change the calculation?

Yes. A salt form has a different molecular mass from free glucoraphanin, so the milligram ratio changes. The exact chemical form must be known before doing a theoretical mass calculation.

Does active myrosinase guarantee complete conversion?

No. Active myrosinase can support conversion, but formulation, enzyme activity, reaction conditions, digestion and individual biology still affect the result.

What is the difference between theoretical yield, tested product yield and bioavailability?

Theoretical yield is a chemistry ceiling, tested product yield is measured under a defined product method, and bioavailability is measured in people using a stated biological marker such as urinary metabolites.

Can equal glucoraphanin amounts produce different sulforaphane exposure?

Yes. Human studies show that the same glucoraphanin amount can produce different measured recovery when enzyme supply, formulation and individual conversion differ.

Does a guaranteed minimum 6 mg mean every person absorbs 6 mg?

No. It is a finished-product minimum supplied by the brand, not a guarantee that every person absorbs 6 mg or excretes an equivalent amount of urinary metabolites.

How should clinical-trial doses be compared with supplement labels?

Match the chemical form, units, formulation, enzyme activity, serving basis and measurement method. Do not transfer a study percentage or metabolite result to a different product without supporting evidence.

Next Steps

For more context before comparing labels, read our guides to choosing a glucoraphanin supplement, the sulforaphane dosage guide, and comparing sulforaphane supplement formats.

You can also explore the role of sulforaphane and Nrf2, learn why three-day-old broccoli sprouts matter, or browse our broccoli sprouts collection.

References

1. PubChem. Glucoraphanin compound record. https://pubchem.ncbi.nlm.nih.gov/compound/Glucoraphanin
2. US Food and Drug Administration Global Substance Registration System. Sulforaphane, S form. https://precision.fda.gov/ginas/app/ui/substances/7J94TPZ10L
3. Mastaloudis A, Holcomb L, Fahey JW, and colleagues. Exogenous myrosinase from mustard seed increases bioavailability of sulforaphane from a glucoraphanin-rich broccoli seed extract in a randomized clinical study. Scientific Reports. 2026. https://www.nature.com/articles/s41598-026-39389-4
4. Fahey JW, Holtzclaw WD, Wehage SL, Wade KL, Stephenson KK, Talalay P. Sulforaphane Bioavailability from Glucoraphanin-Rich Broccoli: Control by Active Endogenous Myrosinase. PLOS ONE. 2015. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0140963
5. NIH Dietary Supplement Label Database. Sulforaphane ingredient terminology. https://dsld.od.nih.gov/ingredient/Sulforaphane
6. NIH Office of Dietary Supplements. Dietary Supplement Label Database overview. https://ods.od.nih.gov/Research/Dietary_Supplement_Label_Database.aspx
7. Kiwi Superfoods. Broccoli Sprout Powder product page. /products/broccoli-sprout-powder-1

This article is for general education and does not replace personalised medical or nutritional advice. Product responses vary.