Silage Storage Capacity Calculator
Calculate how many tons of silage a cylindrical upright silo can hold based on its diameter, height, and the packed density of your forage. Use it when sizing a new silo or checking existing storage before harvest.
About this calculator
An upright silo is a cylinder, so its volume is calculated using the standard formula V = π × r² × h, where r is the radius (half the diameter) and h is the height in feet. To convert cubic feet of volume into tons of silage, multiply by the silage density in pounds per cubic foot, then divide by 2,000 (pounds per ton). The full formula is: Capacity (tons) = π × (diameter / 2)² × height × silage_density / 2,000. Packed silage density varies by crop and moisture: high-moisture corn silage typically packs at 40–50 lbs/cu ft, while drier haylage may be 30–35 lbs/cu ft. Accurate density values are essential because a 10 lb/cu ft error on a large silo can mean hundreds of misallocated tons of feed.
How to use
Suppose your concrete stave silo is 20 ft in diameter and 60 ft tall, and you plan to store corn silage at a packed density of 45 lbs/cu ft. Step 1 — Calculate radius: 20 / 2 = 10 ft. Step 2 — Compute volume: 3.14159 × 10² × 60 = 18,850 cu ft. Step 3 — Convert to tons: 18,850 × 45 / 2,000 = 424 tons. So this silo holds approximately 424 tons of corn silage, enough to feed a 100-cow dairy herd for roughly four months at typical intake rates.
Frequently asked questions
What silage density should I use for corn silage versus haylage in storage calculations?
Corn silage packed in an upright silo typically reaches 40–50 lbs per cubic foot at 60–65% moisture. Haylage stored at 45–55% moisture is lighter and usually packs at 30–38 lbs per cubic foot. Using a density that is too low will overestimate capacity and leave you short of winter feed. It is best to weigh and measure a representative sample from your own operation or consult university extension forage tables specific to your region.
How does silo height affect silage storage efficiency and quality?
Taller silos store more volume for the same footprint, but they also apply greater compressive weight on lower layers, which actually improves packing density and anaerobic conditions. However, very tall silos require more powerful blowers and increase safety risks during filling and unloading. Most agronomists recommend a height-to-diameter ratio of 3:1 to 4:1 for upright silos to balance storage efficiency with structural integrity and safe operation.
How much silage does a dairy cow need per day and how does that help me size my silo?
A lactating Holstein cow typically consumes 40–50 lbs of corn silage per day on a fresh-weight basis, or roughly 7–10 lbs of dry matter. Multiplying daily intake by herd size by the number of feeding days gives you total silage demand in pounds, which you can then divide by 2,000 for tons. Comparing that demand figure to your silo capacity calculation reveals whether you need additional storage before harvest, helping you avoid costly emergency feed purchases mid-winter.