# Fodder Storage Capacity Calculator

> Work out the tonnes of silage or hay a clamp, bunker or barn holds from its size and the fodder’s bulk density, and how many days it will feed your animals.

Category: Agriculture · Applies to: Worldwide · Last updated: 2026-10-29
Interactive calculator: https://calculators.geekmidst.com/calculators/fodder-storage-capacity-calculator

Storage capacity is volume times bulk density. Divide what is left after losses by the herd’s daily intake to see how many days of feed you have.

Also called: Silage clamp calculator, Bunker silo calculator, Hay storage calculator.

## Inputs
- Units (options: Metric (m, kg), Imperial (ft, lb); default metric)
- Length (default 30)
- Width (default 10)
- Average height of fodder (default 3)
- Share of the space filled (unit %; default 100)
- Bulk density (as stored) (default 650)
- Storage and feeding losses (unit %; default 10; optional)
- Animals fed (default 50)
- Fodder per animal per day (as fed) (default 35)

## Results
- Days of feed
- Fodder stored
- Usable after losses
- Usable after losses
- Filled volume
- Filled volume
- Herd use per day

## Formula

```
Volume = L × W × H × Fill%;  Stored = Volume × Density;  Days = Stored × (1 − Losses%) ÷ (Animals × Intake)
```

Where:
- Density: mass of fodder per unit volume as stored (1 lb/ft³ = 16.018 kg/m³)
- Losses: dry-matter loss, spoilage at the face and feed-out waste
- Intake: as-fed fodder per animal per day

## Worked example
1. Volume = 30 × 10 × 3 = 900 m³.
2. Stored = 900 × 650 kg/m³ = 585 t; after 10% losses = 526.5 t.
3. Days = 526,500 kg ÷ (50 × 35 kg) = 526,500 ÷ 1,750 = 300.9 days.

**Result:** A 30 × 10 m clamp filled 3 m deep holds about 585 t of silage, enough for 50 cows eating 35 kg a day for about 301 days.

## What the result means

Compare the days of feed with the length of your feeding period; if it falls short, plan bought-in fodder early. Measuring the actual density with a core sample improves the estimate more than anything else.

## Assumptions and limits
- The store is a rectangular block of fodder with an even height.
- Sloped clamp walls and domed tops are not modelled; use an average height.
- Intake is as-fed, so a change in dry matter changes the days of feed.

## Questions

### What bulk density should I use?

It varies widely: well-compacted wet silage is much denser than dry hay, and bales differ by size and press. Weigh a few bales or take a core sample from the clamp.

### Should I count feed in kg as fed or dry matter?

Either, as long as the density and intake use the same basis. This page uses as-fed weight for both.

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- [Grain Storage Volume Calculator](https://calculators.geekmidst.com/calculators/grain-storage-volume-calculator)
- [Livestock Feed Ration Calculator](https://calculators.geekmidst.com/calculators/livestock-feed-ration-calculator)
- [Cattle Milk Yield Calculator](https://calculators.geekmidst.com/calculators/cattle-milk-yield-calculator)

Source: GM¹X CalcVerse — https://calculators.geekmidst.com/calculators/fodder-storage-capacity-calculator