Assay · Moisture

Assay and moisture price comparison calculator

Compare supplier quotes on what you actually receive, not the headline.

Enter up to three quotes with assay and moisture, and get each price per 100% active and per dry unit, ranked.

Last updated 2026-09-27. Math runs in your browser, no data leaves your computer.

Put every quote in the same currency and the same unit before you start, since the tool compares numbers and does not convert currencies. Take assay and moisture from each supplier's certificate of analysis or specification sheet, not from the sales email.

The unit only labels the result, but every quote has to use it, so convert any outlier quote before you type it in.

Quote 1

A short name is enough, since it only labels the row in the comparison table below.

Use the price on the same Incoterm for every quote, because an FOB price against a CIF price hides the freight inside one of them.

Use the guaranteed minimum on the specification, not the typical value, since the minimum is what you can claim against.

The certificate names the basis next to the result, and a dry basis figure always flatters a wet product.

Use the maximum water or loss on drying from the specification, or 0 for a product sold as a solution where water is the solvent.

Quote 2

A short name is enough, since it only labels the row in the comparison table below.

Use the price on the same Incoterm for every quote, because an FOB price against a CIF price hides the freight inside one of them.

Use the guaranteed minimum on the specification, not the typical value, since the minimum is what you can claim against.

The certificate names the basis next to the result, and a dry basis figure always flatters a wet product.

Use the maximum water or loss on drying from the specification, or 0 for a product sold as a solution where water is the solvent.

Quote 3 (optional)

A short name is enough, since it only labels the row in the comparison table below.

Use the price on the same Incoterm for every quote, because an FOB price against a CIF price hides the freight inside one of them.

Use the guaranteed minimum on the specification, not the typical value, since the minimum is what you can claim against.

The certificate names the basis next to the result, and a dry basis figure always flatters a wet product.

Use the maximum water or loss on drying from the specification, or 0 for a product sold as a solution where water is the solvent.

Before the booking, screen the name on the invoice. Shipment pre-check is on the paid plans, from USD 59 a month.

General guidance only. Verify against the cited primary sources before you commit to a shipment, declaration, or contract.

Why the headline price misleads

Two suppliers can quote the same product name at prices a few percent apart while shipping very different amounts of the thing you are paying for. One quotes a high assay on a dry basis and ships a wet product, the other quotes a lower looking assay on an as is basis and ships it dry, and the buyer who compares headline prices signs the more expensive contract without knowing it.

The tool works out the dry fraction as one minus the moisture, then the active fraction as received. For an as is assay that is the assay itself, and for a dry basis assay it is assay x (1 minus moisture). Price per 100% active is the quoted price divided by the active fraction, and price per dry unit is the quoted price divided by the dry fraction.

If a quote's as is assay plus its moisture comes to more than 100%, the numbers on the certificate cannot all be true on the same basis, and the tool flags it. That usually means the assay is really on a dry basis, so ask the supplier to confirm before you rely on the ranking.

Worked example: two powder quotes 40 apart

The booking. Supplier A quotes USD 1,000 per metric ton at 98% assay, and Supplier B quotes USD 1,040 per metric ton, also at 98% assay. The buyer sees the same assay on both offers and a saving of 40 per ton with Supplier A, which looks fine on paper.

The failure. Supplier A's assay is on a dry basis with 8% moisture, so each ton delivers 0.98 x 0.92 = 0.9016 tons of active and costs USD 1,109.14 per ton of active. Supplier B's assay is as is, so it costs 1,040 / 0.98 = USD 1,061.22 per ton of active, and the cheap quote is really 4.5% dearer on what the plant uses.

The fix. Put both quotes through the tool with the basis and moisture from each certificate, and it ranks Supplier B first by USD 47.91 per ton of active. The buyer either awards Supplier B or goes back to Supplier A and asks for a price that beats 1,061.22 on the active basis, which is a far stronger position than haggling over the headline.

Scoring the same offers on lead time, minimum order and payment terms as well as price? The RFQ comparison matrix weights each factor and ranks up to five suppliers.

Want the delivered cost once freight, duty and fees sit on top of the active price? The landed cost calculator builds the full cost per unit at your door.

Frequently asked

How do I convert a price to a 100% active basis?

Divide the quoted price by the active fraction of the material as it arrives. If the assay is quoted on an as is basis, the active fraction is the assay itself, and if it is quoted on a dry basis, multiply the assay by one minus the moisture first. A price of 1,000 per metric ton at 98% dry basis assay and 8% moisture is 1,000 / (0.98 x 0.92) = 1,109.14 per ton of active.

What is the difference between as is and dry basis assay?

An as is assay measures the active content in the sample exactly as received, water included. A dry basis assay measures it after the sample has been dried, so it reads higher on a wet product. The certificate of analysis should state which basis applies, usually next to the method reference, and if it does not, ask before you compare quotes.

When should I compare on a dry basis instead of active basis?

Compare per dry unit when you pay for solids but the active content is not the thing you value, such as a filler or a carrier where the water is dead weight in freight and in the mixer. Compare per 100% active when the active ingredient is what does the work, which covers most acids, salts, actives and intermediates.

Does the tool include freight on the water?

No, it compares the unit price only. Water also costs freight, duty on a value basis and handling, so a wet product at 8% moisture moves 8 tonnes of water in every 100 tonnes shipped, and the landed cost gap is usually wider than the price gap this tool shows.

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