Dry matter basis calculator: compare any two dog foods

What a dry matter basis is

A dry matter basis restates every percentage on a pet food label as a share of the food with the water removed. Divide the printed percentage by 100 minus the moisture percentage, then multiply by 100. That one step is what makes a can and a bag comparable, because it takes the water out of the denominator on both sides.

The reason it is needed is that a guaranteed analysis panel answers a question nobody asked. It reports what share of the product in the container is protein, and the container holds water. Two foods with identical dry matter protein will print wildly different figures if one carries four times the water of the other, and neither label is wrong. They are simply denominated differently, in the same way that two prices in two currencies are both correct and still uncomparable.

Because the moisture figure is the only divisor, one number converts every line on a label at once. Find your own moisture percentage in the table below and the third column is the number to multiply protein, fat and fibre by. It is the same arithmetic the calculator above runs, printed out so you can check it without typing anything.

No food is named in that table and none is implied. It is the function itself, tabulated in even steps: read across from whatever your own label says.

Why a canned food that looks lower in protein usually is not

A canned food prints a low protein percentage because most of what that percentage is measured against is water. Suppose a can says 78% moisture: only 22% of it is food, so a printed 9% protein is 9% of the whole can rather than of the part that feeds the dog. Converted, it is 40.9%.

Now put a dry food beside it. Suppose that label says 10% moisture and 26% protein. Its multiplier is only 1.11, because there was barely any water to remove, so it converts to 28.9%. As printed, the dry food looked 17.0 points ahead. On a dry matter basis the wet food is 12.0 points ahead. Nothing about either food changed; only the denominator did.

Those two labels are hypothetical, chosen to show the arithmetic rather than to describe any real product, and the size of the reversal depends entirely on the two moisture figures. That is the point worth carrying away: how far a comparison misleads you is set by how far apart the two moisture percentages are, and you can read both off the labels before you convert anything.

How to read the guaranteed analysis panel

Four lines matter here, and they are printed together in one block: crude protein and crude fat as minimums, crude fibre and moisture as maximums. Copy them in exactly as printed, decimals included. The panel is a guarantee rather than a measurement, so the real figures sit at or beyond those bounds, and that is the honest limit of any dry matter comparison.

In practice this means the converted numbers are a floor for protein and fat and a ceiling for fibre, not a reading. When two foods land within a point or so of each other after conversion, treat that as a tie rather than a result, because the guarantees they were built from are not precise enough to separate them. When they land ten points apart, the gap is real.

The panel also does not add up to 100, in either basis, and it is not supposed to. Ash and carbohydrate are not required lines, so they are usually missing, and the remainder of the food sits in them. This converter leaves that gap open rather than filling it with an assumed ash figure: a carbohydrate estimate built on a number the label never printed would be a guess wearing the clothes of a calculation, and it would be the one figure on the page you could not check.

What this converter does not tell you

It does not tell you which food is better. A dry matter basis puts two labels on one scale and stops there. It says nothing about ingredient quality, amino acid profile, digestibility, calorie density, or whether either food suits the dog in your house. Two foods can match on every converted line and behave completely differently in the bowl.

Two follow-on questions are worth naming because the conversion cannot answer them. The first is how much of the food to serve, which is a calorie question rather than a percentage one and belongs to the feeding calculator, where the figure that matters is calories per cup off the same bag. The second is whether the current food is working at all, which no label can answer and a hands-on body condition check answers in about a minute.

Cost is the third. A dry matter comparison of two foods says nothing about what either costs to feed for a year, because that depends on calorie density and how much of the container is water you are paying to ship. The cost calculator handles the money side, and the breed profiles carry the published adult weight range that sets the portion in the first place.

Method and sources

There are no sources on this page, because there is no outside data on it. Every figure the calculator prints is either a number you typed off your own label or the result of one division applied to it. Nothing is estimated, averaged, or filled in from a database of typical foods, and no default value is pre-loaded into any field.

That is deliberate, and it is the reason this tool can be trusted in a way a lookup table cannot. A published average for a food category would be out of date the week after it was written and wrong for most individual products the day it was written. The bag in your hand is not an average of anything, so the only honest input is the panel on the back of it. Here is where each figure comes from.

• Protein, fat, fibre and moisture, as fed — Typed by you, off the guaranteed analysis panel of the bag or can in front of you.
• Dry matter percentage — 100 minus the moisture figure you typed. Nothing else feeds into it.
• Multiplier — 100 divided by the dry matter percentage. It is the same for every line on one label.
• Protein, fat and fibre on a dry matter basis — Each as-fed figure divided by the dry matter percentage, times 100.
• The gap between two foods — Subtraction of the two dry matter protein figures above, in percentage points.

Nothing you type is saved or sent anywhere; the arithmetic runs in your browser. How we write and correct these pages and where the data behind our other tools comes from.

Common questions

What is dry matter basis in dog food?

Dry matter basis is every percentage on the label restated with the water taken out. A guaranteed analysis panel reports protein, fat and fibre as a share of the whole product, water included, so a food that is mostly water reports small percentages. Removing water from the denominator puts every food on one scale, which is the only way a can and a bag can be compared.

How do you calculate dry matter basis?

Divide the printed percentage by 100 minus the moisture percentage, then multiply by 100. Protein of 9 percent on a label that also says 78 percent moisture becomes 9 divided by 22, times 100, which is 40.9 percent. The same divisor applies to every line on that label, so one number does the whole conversion.

Why does canned dog food show less protein than kibble?

Because the percentage is measured against the whole can, and most of a can is water. That water is counted in the denominator but feeds nothing, so it pushes every printed percentage down. The kibble is not diluted the same way, so its printed figures start close to their dry matter values. Converting both is what removes the illusion.

Can I compare wet and dry dog food directly from the label?

No. As-fed percentages are only comparable between foods with the same moisture, and wet and dry foods are nowhere near each other on that measure. Comparing them as printed is like comparing two prices in different currencies without converting. Run both labels through the converter above and read the dry matter columns instead.

Why do the percentages not add up to 100?

Because a guaranteed analysis panel is not a full breakdown. It prints four to six required lines and leaves out ash and carbohydrate, which together make up the remainder. This converter does not estimate the missing lines, because guessing what a label does not print would undo the reason the conversion is trustworthy.

Does a higher dry matter protein mean a better food?

No. Dry matter basis is a unit conversion, not a quality score. It says how much protein is in the food once the water is out; it says nothing about where that protein comes from, how digestible it is, how many calories the food carries, or whether it suits your dog. Use it to compare like with like, then judge the food on everything else.