What is a typical DM% for corn silage?

Well-made corn silage is typically 30-38% dry matter (62-70% moisture). The target harvest moisture for corn silage in bunker silos is 65-70% (30-35% DM), and for upright silos 60-65% (35-40% DM).

How much shrink should I plan for?

Well-managed bunkers with good packing and covering typically lose 8-12% of as-fed tonnage. Uncovered piles or poorly packed bunkers can lose 15-30%. Bag silos typically have the lowest losses at 3-8%.

How do I estimate bunker silo capacity?

Measure the dimensions of your bunker in feet (length × width × average depth). Multiply by the pack density (typically 40-50 lbs/cu ft for corn silage). Divide by 2,000 to convert to tons. Compare against your calculated need.

Can I mix silage with hay?

Yes. Many rations combine silage and hay. Calculate the DM contribution from each and adjust the silage quantity accordingly. For example, if half of DMI comes from silage and half from hay, halve the silage DMI input.

What if my silage is wetter or drier than expected?

Wetter silage means you need more tons as-fed to supply the same DM. Drier silage means fewer tons. Always test silage DM% at feedout and adjust delivery amounts to maintain the correct DM intake.

How does silage compare to hay nutritionally?

Corn silage is typically higher in energy (TDN 65-72%) but lower in crude protein (7-9%) compared to good legume hay. Silage also maintains more consistent quality once ensiled, while hay quality degrades over storage time.

Silage Quantity Calculator

Calculate tons of silage needed (as-fed) by converting dry-matter requirements based on silage moisture content. Free silage planning tool for farms.

Silage Type

Storage Method

Number of Head

Daily Silage DMI

lbs DM/head

Feeding Days

Silage DM %

Shrink / Loss

Silage Price

$/ton as-fed

DM Required

324.0 tons

648,000 lbs dry matter

As-Fed Silage Needed

925.7 tons

At 35% dry matter

Total to Harvest

1,028.6 tons

Including 10% shrink (102.9 tons lost)

Total Feed Cost

$56,571.00

At $55/ton as-fed

Cost per Head

$282.86

Over 180-day period

Cost per Head/Day

$1.57

Daily silage feed cost per animal

As-Fed per Head/Day

51.4 lbs

Wet silage pounds per head daily

Est. Bunker Area

4,675 sq ft

At 10 ft depth (~46,753 cu ft)

Harvest vs. Shrink Loss

Fed 90%

Shrink 10%

Monthly Feed Breakdown

Month	Days	As-Fed (tons)	Incl. Shrink (tons)	Cost
1	30	154.3	171.4	$9,429.00
2	30	154.3	171.4	$9,429.00
3	30	154.3	171.4	$9,429.00
4	30	154.3	171.4	$9,429.00
5	30	154.3	171.4	$9,429.00
6	30	154.3	171.4	$9,429.00

Silage Dry Matter Reference

Silage Type	Typical DM %	Ideal pH	Notes
Corn Silage	30-38%	3.7-4.2	Most common; high energy
Legume Haylage	28-35%	4.0-4.5	High protein source
Grass Haylage	35-45%	4.2-4.8	Good fiber source
High-Moisture Corn	22-28%	3.8-4.3	Energy concentrate
Sorghum Silage	28-35%	3.8-4.3	Drought-tolerant option
Small Grain	25-32%	4.0-4.5	Boot to soft-dough stage

Planning notes, formulas, and examples

About the Silage Quantity Calculator

The Silage Quantity Calculator determines how many tons of silage (on an as-fed basis) you need to meet your herd’s dry-matter requirements. Because silage typically contains only 30-40% dry matter (60-70% moisture), the as-fed tonnage is significantly higher than the dry-matter requirement — a fact that can surprise producers who are used to thinking in hay tons.

Accurate silage inventory planning prevents the costly problem of running short before the next harvest. Buying silage on the open market is expensive due to high trucking costs relative to value. Building too large a silage pile wastes money and risks spoilage if the pile’s face isn’t consumed fast enough.

This calculator converts your herd’s total dry-matter need for the feeding period into as-fed silage tons, accounting for the silage’s moisture content. It works for corn silage, grass silage, haylage, or any ensiled forage. Enter DM requirements and silage DM percentage to get your purchase or production target.

When This Page Helps

Silage moisture makes quantity planning tricky — a ton of silage contains far less dry matter than a ton of hay. This page helps you translate dry-matter demand into realistic as-fed tonnage before building piles, booking chopper acres, or buying feed.

How to Use the Inputs

Enter the number of head to be fed silage.
Enter the daily dry-matter intake from silage per head.
Enter the number of feeding days.
Enter the silage dry-matter percentage (typically 30-40% for corn silage).
Enter a shrink/waste factor if applicable.
Review the as-fed tons of silage needed.

Formula used

DM requirement (tons) = Head × DMI from silage (lbs/day) × Feeding days / 2,000
As-fed tons = DM requirement / (Silage DM% / 100) / (1 − Shrink%)

Where:
DMI from silage = Portion of daily dry-matter intake supplied by silage
Silage DM% = Dry-matter percentage of the silage (typically 30-40%)
Shrink% = Storage and feedout losses

Example Calculation

Result: 2,057 tons as-fed

DM needed = 200 × 18 × 180 / 2,000 = 324 tons DM. As-fed = 324 / 0.35 = 925.7 tons. With 10% shrink: 925.7 / 0.90 = 1,028.6 tons. Wait—let me recalculate: 324 / 0.35 / 0.90 = 1,028.6. For 200 head at 18 lbs DM/day for 180 days, you need approximately 1,029 as-fed tons of 35% DM silage.

Tips & Best Practices

Test silage DM% at harvest — it varies with maturity, weather, and wilting time.
Plan for 5-15% shrink from fermentation losses and feedout waste.
Corn silage at 65% moisture weighs about 45 lbs per cubic foot in a well-packed bunker.
Feed at least 6 inches off the bunker face daily to minimize spoilage.
Properly sealed and covered piles reduce shrink losses significantly.
Account for all livestock classes being fed silage, including heifers and backgrounding cattle.

Why Moisture Content Matters So Much

A ton of 35% DM corn silage contains only 700 lbs of actual dry matter. A ton of 88% DM hay contains 1,760 lbs. You need 2.5 times more silage tonnage to deliver the same dry matter as hay. This moisture difference is the most common source of silage inventory miscalculation.

Optimizing Silage Production

To match your feeding needs, work backward from this calculator’s result to determine harvest acreage. Divide as-fed tons needed by expected yield per acre (typically 15-25 tons/ac for corn silage). Add 10% for field losses to get your target harvest acres.

Monitoring Silage Quality

Test silage within 30-60 days of harvest and again mid-feed season. Moisture, pH, and nutrient content can change over time, especially in the top and edges of bunkers. Adjust rations based on current test results rather than harvest-time values.

Sources & Methodology

Last updated: February 10, 2026

Frequently Asked Questions

Well-made corn silage is typically 30-38% dry matter (62-70% moisture). The target harvest moisture for corn silage in bunker silos is 65-70% (30-35% DM), and for upright silos 60-65% (35-40% DM).