How many pounds of silage are in a cubic foot?

Bulk as-fed density depends on dry-matter packing density and moisture content: Bulk density (lb fresh/ft³) = DM density ÷ dry-matter fraction. For example, 14 lb DM/ft³ at 65% moisture (35% DM) equals 40.0 lb as-fed/ft³. Use a measured density or a local Extension recommendation when available.

What silage packing density should I use?

Use a measured dry-matter density from your storage when possible. The crop presets are editable planning examples; density varies with crop, moisture, packing, particle size, storage geometry, and sampling method.

What is silage shrink and why should it be deducted?

Shrink represents inventory lost during storage and feedout. The calculator uses an editable 15% planning assumption, but farm records or a qualified local adviser should replace that default. Net feedable inventory equals gross inventory multiplied by one minus the selected shrink percentage.

How is dry matter tonnage calculated?

Dry matter tons = fresh weight tons × (1 − moisture fraction). For example, corn silage at 65% moisture has 35% dry matter, so 100 fresh tons contains 35 dry matter tons. This tool accepts either a preset crop moisture or a custom value you enter.

How are equivalent 1,400 lb round hay bales calculated?

Comparisons are calculated on an equivalent dry-matter basis, not raw wet weight. A standard 1,400 lb round hay bale at ~15% moisture contains approximately 1,190 lb of dry matter (1,400 × 0.85). Wet silage at 65% moisture contains only 35% dry matter, so dividing wet silage pounds by 1,400 would severely overestimate hay equivalence.

What is TDN and why does it matter?

Total Digestible Nutrients (TDN) is an energy estimate expressed as a percentage of dry matter. Multiplying net feedable dry-matter tons by the entered TDN percentage gives estimated feedable TDN tons. Use a forage analysis for ration decisions.

How does the drive-over pile shape differ from a bunker?

A bunker or trench silo has vertical walls and a flat floor, modeled as a rectangular prism (Volume = L × W × H). A drive-over pile is modeled here as a triangular prism (Volume = 0.5 × L × W × H). Note that actual drive-over piles with flat top plateaus and specific ramp approach slopes may deviate slightly from this geometric approximation.

What moisture level should I use for corn silage?

Corn silage harvested at the recommended two-thirds milk-line stage typically runs 62–68% moisture (32–38% dry matter). Wetter silage (above 70%) risks seepage losses; drier silage (below 55%) is harder to pack and may heat. If you have a recent forage test, use that moisture figure for the most accurate result.

Silage Calculator

Enter the dimensions, density, and shrink of your silage pile or bunker to estimate gross packed tonnage, net feedable dry matter, and herd feedout days.

Silage Pile Inputs

Pile / Silo Type

Rectangular cross-section (L × W × H) — vertical walls, flat floor.

Length (ft)

Width (ft)

Height (ft)

Enter interior dimensions in feet. For drive-over piles, height is peak center height.

Storage & Spoilage Shrink (%)

Editable planning assumption. Replace 15% with your storage and feedout records.

Crop Type

Moisture (%)

Density (lb DM/ft³)

TDN (% DM)

Calculated bulk density: ~40.0 lb as-fed/ft³

Herd Feedout Supply (Optional)

Herd Size (head)

Daily Intake / Head

Intake Basis

Results

Fill in the inputs and click Calculate.

Assumptions, privacy, and sources

All calculations run locally in your browser; the values you enter are not sent to an external calculation service.
Bunkers use a rectangular-prism estimate. Drive-over piles use a simple triangular-prism estimate; flat tops, side slopes, ramps, settling, and irregular faces can materially change actual volume.
Density, moisture, shrink, and TDN are user-controlled assumptions. Measure inventory and use a forage analysis for purchasing, ration, insurance, or lending decisions.
Hay equivalence uses net feedable dry matter and assumes each 1,400 lb hay bale is 85% dry matter. It is not a nutritional substitution ratio.

Planning references: SDSU Extension silage resources, Manitoba Agricultural Services storage calculator, and Pioneer silage capacity reference.

Summary

Enter the dimensions, density, and shrink of your silage pile or bunker to estimate gross packed tonnage, net feedable dry matter, and herd feedout days.

How it works

Select the silage pile type: drive-over pile (triangular cross-section) or bunker/trench silo (rectangular cross-section).
Enter the pile dimensions: length, width, and height (or peak height for a drive-over pile).
Set your estimated storage and feedout shrink; the editable 15% default is a planning assumption, not a measured farm value.
Select the crop type or enter a custom moisture percentage to set dry matter content.
Enter the dry matter packing density in pounds of DM per cubic foot (typical values are pre-filled).
Optionally enter herd size and daily intake per head to calculate days of feed supply.
Click Calculate to inspect gross packed inventory, net feedable tonnage, TDN energy, and hay bale equivalence.

Use cases

Estimate how many tons of silage are in an existing pile before feeding season.
Distinguish gross harvested inventory from net feedable inventory by accounting for shrink.
Plan bunker or drive-over storage capacity when harvesting corn, sorghum, or grass silage.
Compare pile volumes and densities across different fields or crop years.
Calculate dry matter intake requirements and estimate how many days the inventory will feed the herd.
Verify silage inventory for lender or insurance reporting.
Convert silage inventory to equivalent 1,400 lb dry hay bales on a normalized dry-matter basis.
Budget silage supply for custom feedlot or dairy ration planning.
Cross-check core probe density readings against calculated as-fed bulk density.

Frequently Asked Questions

Last updated: 2026-09-22 · Reviewed by Nham Vu