Dry Matter Calculator

Find dry matter percentage and moisture content from fresh and oven-dry sample weights, and convert a nutrient value to a dry-matter basis.

Quick Facts

Formula
DM% = (dry weight / fresh weight) × 100
Moisture % = 100 − DM%. Weigh both fresh and oven-dry in the same units.

Your Results

Calculated
Dry matter
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Share of fresh weight that is solids
Moisture content
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Water lost during drying
Water removed
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Fresh weight − dry weight
Nutrient on DM basis
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As-fed % ÷ (DM% / 100)

Ready

Enter fresh and dry weights, then calculate.

About dry matter

Dry matter (DM) is everything in a plant, feed, or food sample except water — the protein, fiber, sugars, fats, minerals, and other solids that remain after all the moisture has been driven off. It is expressed as a percentage of the fresh (as-received) weight. Because water carries no nutritional value but adds a lot of weight, agronomists, livestock nutritionists, and food scientists work in dry matter terms so that samples with very different moisture contents can be compared fairly.

The formula

Dry matter percentage is the ratio of the oven-dry weight to the fresh weight, expressed as a percentage:

DM% = (dry weight ÷ fresh weight) × 100

Moisture content is simply the complement of dry matter:

Moisture % = 100 − DM%

The weight of water removed equals the fresh weight minus the dry weight. As long as both weights use the same unit (grams, kilograms, pounds), the resulting percentage is unit-independent. To measure dry matter you weigh a fresh sample, dry it to a constant weight — typically in a forced-air oven at 60–65 °C for forages destined for further analysis, or 100–105 °C for a quick total-solids reading — then weigh it again.

Converting nutrients to a dry matter basis

Feed analyses are often reported two ways: "as-fed" (including moisture) and "dry matter basis" (moisture removed). To move a nutrient concentration from an as-fed value to a dry matter basis, divide by the dry matter fraction:

Nutrient (DM basis) = as-fed % ÷ (DM% ÷ 100)

For example, a corn silage at 35% dry matter that tests 8% crude protein as-fed contains 8 ÷ 0.35 = 22.9% crude protein on a dry matter basis. Comparing feeds on a dry matter basis prevents a wet feed from looking artificially "diluted" next to a dry one.

Common reference points

  • Fresh pasture and lush grazing: roughly 15–25% dry matter (75–85% water).
  • Corn (maize) silage at harvest: about 30–38% dry matter.
  • Grass or legume hay, well cured: 85–90% dry matter (10–15% moisture).
  • Cereal grains such as corn and wheat: around 86–89% dry matter.
  • Most fresh fruits and vegetables: 5–20% dry matter, since they are mostly water.

Frequently Asked Questions

What is the formula for dry matter percentage?
Dry matter percentage equals the dry weight divided by the fresh (wet) weight, multiplied by 100: DM% = (dry weight / fresh weight) × 100. Moisture content is 100% minus the dry matter percentage. A forage that weighs 200 g fresh and 60 g after oven drying is 30% dry matter and 70% moisture.
How do I convert a nutrient from as-fed to a dry matter basis?
Divide the as-fed value by the dry matter fraction: nutrient on DM basis = as-fed value / (DM% / 100). A silage at 35% dry matter listed at 8% crude protein as-fed contains 8 / 0.35 = 22.9% crude protein on a dry matter basis. Feeds are compared on a dry matter basis so water content does not distort the comparison.
What oven temperature and time should I use?
For a quick total-solids or moisture reading, dry to constant weight at 100–105 °C. For forage or feed samples that will undergo further chemical analysis, use a lower 60–65 °C so heat-labile compounds and volatiles are not lost. In every case, "dry to constant weight" means re-weighing until the mass stops falling — a single timed run can leave residual moisture.
Why compare feeds on a dry matter basis instead of as-fed?
Water adds weight but no nutrients, so an as-fed comparison penalizes wet feeds. A pasture at 20% dry matter and a hay at 88% dry matter might supply similar protein per unit of dry matter, yet look wildly different as-fed. Ration balancing, intake targets, and nutrient requirements are all expressed on a dry matter basis for exactly this reason.

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