Price per kg Active Ingredient Calculator for Chemical Quotes

This price per kg of active content method compares offers of the same active substance in the same form, used for the same job. It does not rank blends of different actives or products whose performance does not follow active content, and it leaves out freight, hazardous goods charges, payment terms and the cost of a failed batch.

When should you compare chemical quotes on price per kg of active content?

Compare chemical quotes on price per kg of active content when two or more offers contain the same active substance at different strengths, or when they are quoted on different bases such as per kg, per liter and per pack. A buyer who pays for a concentrate also pays for its carrier, usually water or a solvent, so the headline price ranks offers by the wrong quantity whenever the strengths differ.

Vesper shows the effect with citric acid. Citric acid monohydrate was priced slightly below the anhydrous form per tonne, but because the monohydrate contains approximately 90% citric acid, its effective cost was 1.611 per kg of citric acid against 1.465 for the anhydrous form (Vesper, accessed 2026). The cheaper tonne bought less acid.

The rule is old. A 1983 guide for golf course superintendents told buyers of turf chemicals: "Do not purchase if the concentration of active ingredient is not listed on the label. Compare prices of 2 or 3 companies before purchasing." (Jones, The Florida Green, 1983).

Typical triggers in industrial purchasing are a supplier offering a more concentrated grade, a tender where bidders quote different pack sizes, a switch from drums to intermediate bulk containers, and a second source qualified for an existing product. In each case the active content and the in-use concentration decide the cost, not the price on the first line of the quote.

Which formulas does the price per kg active ingredient calculator use?

The price per kg active ingredient calculator uses three results for each offer: price per kg as supplied, price per kg of active content, and price per liter of in-use solution. Each one is a single division or multiplication, and the inputs are the quoted price, the quantity that price covers, the density in kg/L, the active content in % w/w and the in-use concentration in % v/v.

The table below decides which formula turns each quote basis into the comparison prices; symbols are P for the quoted price, ρ for density, w for active mass fraction and c for in-use concentration.

The key row is price per kg of active content: 2.50 per kg as supplied at 62% w/w is 4.0323 per kg of active (illustrative). The calculator shows each formula next to its result, so a reader can repeat the arithmetic by hand. The quantity input covers all four quote bases with one expression, mass = kg + L × density, so a per kg quote is entered as 1 kg and a per L quote as 1 L.

How do you convert a price per liter or per pack to price per kg as supplied?

To convert a price per liter to price per kg as supplied, divide it by the product's density in kg/L; to convert a pack price, divide it by the pack's net mass in kg, or by its net volume in L multiplied by the density. A price of 2.75 per L at 1.10 kg/L is 2.50 per kg, and 1,050 for a 1,000 L intermediate bulk container at 1.02 kg/L is 1,050 for 1,020 kg, or 1.0294 per kg (illustrative).

Density depends on temperature, so the density has to come with the temperature it was measured at. ASTM D4052-22 states that determining the density of petroleum products "is necessary for the conversion of measured volumes to volumes at the standard temperature of 15 °C" (ASTM International, 2022). For paints, varnishes and related products of low or medium viscosity, ISO 2811-1:2023 specifies a pycnometer method (ISO, 2023). The FAO and WHO manual adds that a conversion between g/kg and g/l "should be based on measurement of the actual mass per millilitre of the formulation at a specific temperature, not on a nominal value" (FAO and WHO, 2025).

Use the net content of the pack, not the nominal size of the container, and the density from the data sheet or certificate of analysis rather than an assumed 1.00 kg/L. The calculator takes the quantity in kg or in L, never both, and computes the mass as kg plus L times density.

How do you calculate price per kg of active content from % w/w?

Price per kg of active content equals the price per kg as supplied divided by the active content expressed as a mass fraction, which is the % w/w figure divided by 100. A product at 2.40 per kg with 50% w/w active costs 2.40 / 0.50 = 4.80 per kg of active, and one at 2.50 per kg with 62% w/w costs 4.0323 per kg of active (illustrative).

Mass fraction has one definition. NIST SP 811 defines the mass fraction of B as the "mass of substance B divided by the mass of the mixture" (NIST SP 811, 2008, section 8.6.10). The international standard for quantities of physical chemistry is ISO 80000-9:2019, which ISO last reviewed and confirmed in 2025 (ISO, 2019).

Take the assay from the technical data sheet or the certificate of analysis, and use the same kind of figure for every offer: all minimum specification values, or all typical values. A safety data sheet is a poor source for this step. Under the US Hazard Communication Standard, Section 3 of an SDS may give concentration ranges instead of an exact percentage when there is batch-to-batch variability or a trade secret claim (US OSHA, 29 CFR 1910.1200 Appendix D, as of 2026-10-23). Declared content also carries a tolerance: for pesticide formulations declared above 250 up to 500 g/kg, FAO and WHO allow the average measured content to differ from the declared content by ±5% of that content (FAO and WHO, 2025).

How do you compare chemical offers at their in-use dilution?

To compare chemical offers at their in-use dilution, multiply the in-use concentration of the concentrate (as a volume fraction) by the price per kg as supplied and by the density, which gives the price per liter of ready-to-use solution. For an offer quoted per liter, this is simply the in-use fraction times the price per liter: 1.5% v/v of a 2.75 per L concentrate costs 0.0413 per L in use, or 41.25 per 1,000 L (illustrative).

The in-use comparison is the one the buyer pays, because suppliers rarely recommend the same dose for products of different strength. Use the in-use concentration each supplier's technical data sheet gives for the same job, material and water quality, and record where each figure came from.

Ratios need care. A dilution written 1:50 can mean 1 part concentrate in 50 parts of finished solution, which is 2.0% v/v, or 1 part concentrate added to 50 parts water, which is 1/51 or 1.96% v/v (illustrative arithmetic). Ask the supplier which one the data sheet means before converting it.

The calculator also reports the active content delivered per liter in use, in g/L. Two offers at the same in-use price but different g/L tell purchasing that one data sheet doses the active harder than the other, which is a question for the technical team rather than for price negotiation.

Why must w/w and w/v active content not be mixed in a price comparison?

Active content in % w/w and in % w/v must not be mixed in a price comparison because w/v (grams per 100 mL) equals w/w multiplied by the density in kg/L, so the two figures agree only for a liquid at 1.000 kg/L. A product labeled 50% w/v at 1.25 kg/L contains 50 / 1.25 = 40% w/w; treating 50 as a mass fraction understates its price per kg of active content by 20% (illustrative).

NIST treats the label itself as part of the problem. NIST SP 811 states: "One must therefore avoid using phrases such as "percentage by weight," "percentage by mass," "percentage by volume," or "percentage by amount of substance."" and recommends forms such as "the mass fraction is 10 %" (NIST SP 811, 2008, section 7.10.2). A quote that says only "50% active" leaves the basis unstated.

Regulators fix the basis for their own products. US pesticide labels must state the percentage by weight of each active ingredient (US EPA, 40 CFR 156.10(g), as of 2026-10-23). FAO and WHO specifications allow g/kg or g/l at 20 ± 2 °C for many liquids, but in a dispute "the analytical results must be determined and expressed as g/kg" (FAO and WHO, 2025).

Convert every w/v or g/L figure to % w/w before comparing: g/L divided by 10 is % w/v, and % w/v divided by the density in kg/L is % w/w. The calculator's second mode does this and warns when the result is above 100% w/w.

Which inputs and ranges does the active content price calculator accept?

The active content price calculator accepts up to three offers, each with six inputs: the quoted price, the kg or the L that price covers, the density in kg/L, the active content in % w/w and the in-use concentration in % v/v. The price is in any single currency, entered without a symbol, and the calculator does not convert currencies, apply taxes or include discounts and payment terms.

Each input has a range set in the calculator. Density runs from 0.5 to 3.0 kg/L, so a value typed in kg/m3 or a missing decimal point is caught. Active content runs from 0.01 to 100% w/w. In-use concentration runs from 0 to 100% v/v, and 0 skips the in-use price for that offer.

The calculator warns in four cases: when both kg and L are entered for one offer, when neither is entered, when no in-use concentration is given, and when an active content of 100% is entered, since that equates the price per kg of active with the price per kg as supplied and usually means the assay was not checked.

Prices are shown to four decimal places, because price per liter in use is often a small number; g/L and % w/w are shown to two. Round only the figures you report, and keep the unrounded values in the working file so a reviewer can repeat each step.

Active content price comparison of three offers (illustrative)

In an illustrative comparison of three offers for the same active, the offer that is cheapest per kg as supplied and per kg of active content is not the cheapest in use, because its data sheet doses it at a higher concentration. Offer A is quoted at 2.40 per kg, 50% w/w, 1.05 kg/L, dosed at 2.0% v/v. Offer B is 2.75 per L, 62% w/w, 1.10 kg/L, dosed at 1.5% v/v. Offer C is 1,050 per 1,000 L intermediate bulk container, 30% w/w, 1.02 kg/L, dosed at 4.0% v/v.

The table below decides the ranking on each basis for these illustrative offers.

Offer C leads on price per kg as supplied at 1.0294 and on price per kg of active at 3.4314, but Offer B is cheapest in use at 41.25 per 1,000 L against 42.00 for C (illustrative). Offer C's 4.0% dose delivers 12.24 g/L of active against 10.23 g/L for B, so the question for the technical team is whether C needs that much active for the job. The gap between B and C in use is under 2% in this illustrative case, which is close enough that the certificate of analysis tolerance and the dose source deserve a second look before purchasing decides.

How do you present an active-content price comparison to purchasing?

Present an active-content price comparison to purchasing as one table with one row per offer, showing the quote as received, the three calculated prices and the source of every conversion input. Purchasing reads the ranking; the reviewer reads the inputs, so both need to be on the same page.

For each offer, list the quoted price and basis exactly as the supplier wrote it, the density with its measurement temperature and document, the active content with its basis (% w/w) and document, the in-use concentration with the data sheet section it came from, and the date of the quote. Mark every converted figure, such as a w/v value turned into w/w, and state the conversion used.

State the ranking on the basis the plant actually buys and uses, which is usually the price per liter in use, and add the other two rankings when they differ, as in the illustrative case above. Keep costs the formulas exclude, such as freight and handling, in separate lines; a guide on how to show a hazmat surcharge on a chemical quote covers one of them, and the chemical quotation template with unit, basis and terms columns shows where the basis of each line belongs.

Lubinpla's quote drafting does not calculate prices; it puts a source and an as-of date on every value, so each offer's basis can be checked in the quote itself.

Where does a price per kg of active content comparison not apply?

A price per kg of active content comparison does not apply when the offers contain different actives, when the product's performance comes from the whole formulation rather than one active, or when the product is bought on a property instead of a content figure. A corrosion inhibitor package, a lubricant priced on viscosity grade and approvals, and a surfactant blend sold on performance tests all fall outside it; a guide on whether a lubricant price should be per liter or per kg covers that unit choice.

The comparison also stops at the plant gate. Freight, hazardous goods charges, minimum order quantities, storage life, packaging returns and the cost of a failed batch are outside the formulas. A quote that looks cheaper on active content can still lose once those lines are added, which is one reason a chemical quote may not be comparable to a competitor quote.

Assays are not exact. Declared active content carries a manufacturing and analytical tolerance; for pesticide formulations above 500 g/kg, FAO and WHO allow ±25 g/kg or g/l (FAO and WHO, 2025). Treat small differences in price per kg of active as ties unless the certificates of analysis for the delivered lots confirm them.

Finally, the in-use price holds only at the dose each data sheet gives for the same job. If a supplier's recommended dose changes with water hardness, contamination or material, recalculate at the dose that applies to the plant.

Key takeaways

• Rank chemical offers on three prices: per kg as supplied, per kg of active content and per liter in use.

• Convert per liter and per pack prices with the density measured at a stated temperature, not an assumed 1.00 kg/L.

• Use active content as a mass fraction (% w/w) from the data sheet or certificate of analysis, never an SDS range.

• Convert w/v and g/L figures to w/w before comparing; the two agree only at 1.000 kg/L.

• Report the ranking the plant pays, usually per liter in use, with the source of every input.