As-fed ↔ dry matter converter
Convert a weighed feed amount into kilograms of dry matter, or calculate the as-fed amount needed to supply a chosen dry matter amount. Enter the feed’s measured dry matter percentage. Water contributes to the weight you carry and buy, but it is excluded from dry matter comparisons. The calculation stays in your browser.
How does the conversion work?
Dry matter kg equals as-fed kg multiplied by dry matter percentage divided by 100. To reverse the calculation, divide dry matter kg by the percentage and multiply by 100. For example, 20 kg of a feed at 35% dry matter contains 7 kg of dry matter. Supplying that same 7 kg of dry matter requires 20 kg as-fed when the percentage is unchanged. Use these values to follow the arithmetic, then enter your own feed quantity and measured dry matter percentage.
Which percentage should I enter?
Use a representative analysis for the feed batch you actually have. Enter dry matter, not moisture: moisture of 65% corresponds to dry matter of 35%. A catalogue value can illustrate the method but may differ from your silage, hay or by-product. Rain, storage, harvest conditions and batch variation can change water content. Repeat the calculation when the analysis changes instead of assuming every delivery has the same dry matter.
How do I use the result?
Keep the basis beside each number in your notes. Scales and invoices usually describe as-fed weight, while nutrient comparisons often use dry matter. Do not subtract a dry matter amount directly from as-fed stock. First convert it using the same feed percentage. When costing a ration, match the amount and price basis: a price per as-fed kilogram belongs with an as-fed amount. Use the ration cost tool after checking that both refer to the same basis.
How do I build on the result?
Use this result to compare feed weights on the same dry matter basis. Keep each feed’s analysis beside the converted amount, then compare energy, protein, fibre and minerals when planning the whole ration. Record storage losses and feed left in the trough separately to keep the quantity comparison clear. For reverse conversion, enter a dry matter percentage above zero and up to 100, with a zero or positive feed quantity. Keep your current feed analysis and agreed feeding plan beside the result when reviewing a change.
Sources and method
Compiled from open-access scientific sources.
- Meat & Livestock Australia, Beef cattle nutrition, revised March 2015, printed p.16: Intake of feed and dry matter examples. Method: dimensional arithmetic; example percentages are illustrative.