How this calculation works
Silage storage combines a geometry estimate with measured or assumed bulk density. The same volume can hold different fresh masses under different moisture and compaction conditions, so a universal density would hide a major assumption.
Volume = length × height × (bottom width + top width)/2; retained DM = volume × fresh density × DM fraction × (1 − DM loss)A worked example
A ten-metre prism with three- and five-metre parallel widths and two-metre height contains eighty cubic metres. At 600 fresh kg/m³, that is forty-eight fresh tonnes. Thirty-percent DM gives 14.4 dry tonnes. Ten-percent entered DM loss leaves 12.96 dry tonnes, or 259.2 days at fifty kilograms of dry-matter use per day.
Good to know
Uniform trapezoidal fresh-density estimate only; no compaction gradient, dome, fermentation model, structure loading or feed-safety certification. Use site measurements and representative density/DM data. A precise volume does not remove uncertainty in compaction, losses or actual feedout practice.
Reference: Penn State Extension — silage density and losses (opens in a new tab) ↗
What the model answers
Silage storage combines a geometry estimate with measured or assumed bulk density. The same volume can hold different fresh masses under different moisture and compaction conditions, so a universal density would hide a major assumption.
This page represents the stored cross-section as a straight trapezoid repeated along a uniform length. It reports fresh tonnage and dry matter separately before applying an explicit dry-matter loss fraction.
The Feed ration dry matter and protein calculator converts actual daily ingredient masses to a shared dry basis. That can help reconcile the daily-use assumption with a separate storage budget.
Measure and enter consistently
Bottom and top widths describe the actual stored material, not automatically the external bunker dimensions. Height is the filled depth and length is the uniform prism length. A dome or varying end slope is not included.
Density is fresh mass per cubic metre. DM percentage converts that fresh mass to dry matter. A dry-matter density value must not be entered as fresh density and then multiplied by DM percentage again.
Interpret the result
The loss input removes a fraction of dry matter. It does not by itself predict the remaining fresh wet mass, because water and dry matter can change differently during storage and feedout.
Days of use divides retained dry matter by an externally supplied group total per day. The result is a stock budget, not a feeding recommendation or a prediction of spoilage distribution and safe feed quality.
Work through the numbers
A ten-metre prism with three- and five-metre parallel widths and two-metre height contains eighty cubic metres. At 600 fresh kg/m³, that is forty-eight fresh tonnes.
Thirty-percent DM gives 14.4 dry tonnes. Ten-percent entered DM loss leaves 12.96 dry tonnes, or 259.2 days at fifty kilograms of dry-matter use per day.
Where this model stops
Uniform trapezoidal fresh-density estimate only; no compaction gradient, dome, fermentation model, structure loading or feed-safety certification.
Use site measurements and representative density/DM data. A precise volume does not remove uncertainty in compaction, losses or actual feedout practice.
A few questions, answered
Is the loss percentage a fresh-weight loss?
No. It is applied to dry matter only; the tool does not infer a post-storage moisture fraction.
Can I use bunker wall dimensions?
Only if they match the actual filled material geometry represented by the prism.