When shipping goods overseas by sea, moisture is one of the biggest risks that exporters and importers need to consider.
Using the right amount of container desiccant is one of the most effective ways to protect cargo during long-distance shipping.
But a common question from exporters is:
How many container desiccants do I need for a 20ft or 40ft container?
The answer depends on container size, cargo type, shipping route, humidity conditions, and desiccant absorption capacity.
This guide explains the recommended container desiccant quantity for 20ft, 40ft, and 40HQ containers.
Why is Container Desiccant Quantity Important?
Many companies understand the importance of using container desiccants but are unsure about the correct quantity.
Using too few desiccants may not provide enough moisture protection, while using too many increases unnecessary costs.
The goal is to achieve the right balance:
Enough moisture absorption capacity to protect your cargo without wasting money.
For ocean shipments, the required quantity mainly depends on:
- Container volume
- Shipping distance
- Climate conditions
- Cargo moisture sensitivity
- Type and capacity of the desiccant
For example, a shipment of plastic products from China to Europe may require less moisture protection than a shipment of garments or wooden furniture traveling through tropical regions.
What Factors Affect Container Desiccant Quantity?
1. Container Size
The first factor is the size of the shipping container.
A larger container has more air space and usually requires more desiccant.
Typical container sizes:
| Container Type | Internal Volume |
|---|---|
| 20ft Container | Around 28–33 m³ |
| 40ft Container | Around 56–67 m³ |
A 40ft container has almost twice the internal volume of a 20ft container, so it normally requires about double the amount of desiccant.
2. Cargo Type
Different products have different moisture risks.
High moisture sensitivity products:
- Clothing and textiles
- Shoes
- Leather products
- Wooden furniture
- Paper products
- Food packaging materials
These products usually require stronger moisture protection.
Lower moisture sensitivity products:
- Plastic products
- Sealed electronic components
- Metal parts with protective coating
These may require standard protection.
3. Shipping Route and Climate
The shipping environment has a major impact on moisture levels.
High humidity regions include:
- Southeast Asia
- South America
- Africa
- Tropical coastal areas
Long ocean journeys with changing temperatures create a higher risk of condensation.
For these shipments, exporters often increase the number of container desiccants to improve protection.
How Many Container Desiccants Are Needed for a 20ft Container?
For a standard 20ft shipping container, the recommended quantity is usually:
8–10 container desiccants strips
For example, when using calcium chloride container desiccant strips（1.0 kg）:
- Normal shipping conditions: 8 strips
- High humidity conditions: 10–12 strips
A typical 20ft container has around 33 m³ of internal space, so 8 strips of high-capacity container desiccants can provide effective moisture control for many common shipments.
Recommended applications:
- Garments
- Shoes
- Furniture
- General cargo
- Export cartons
For sensitive products or long-distance ocean transportation, additional desiccants may be recommended.
How Many Container Desiccants Are Needed for a 40ft Container?
A 40ft container has approximately twice the space of a 20ft container.
The recommended quantity is usually:
16–20 strips of container desiccants
Example:
Normal shipping:
- 16 strips
High humidity routes:
- 20–24 strips
Because a 40ft container contains more air volume, more moisture can accumulate during transportation.
Using an insufficient quantity may result in moisture problems, especially during long sea voyages.
20ft vs 40ft Container Desiccant Quantity Comparison
| Container Size | Standard Quantity | High Humidity Quantity |
|---|---|---|
| 20ft Container | 8 pcs | 10–12 pcs |
| 40ft Container | 16 pcs | 20–24 pcs |
These numbers are general recommendations. The exact quantity should be adjusted according to:
- Cargo moisture level
- Shipping duration
- Destination climate
- Desiccant absorption capacity
Where Should Container Desiccants Be Placed?
Correct placement is just as important as the quantity.
Even with enough desiccants, poor placement can reduce moisture control performance.
Recommended placement for a 20ft container:
- Place desiccants evenly on both side walls
- Install some units near the container doors
- Avoid placing all desiccants in one area
Example:
- Left side wall: 3–4 strips
- Right side wall: 3–4 strips
- Door area: 1–2 strips
Recommended placement for a 40ft container:
Because of the longer container length:
- Front area: several strips
- Middle area: several strips
- Door area: several strips
The purpose is to create even moisture absorption throughout the container.
What Happens if You Use Too Little Container Desiccant?
Using insufficient desiccant may lead to serious cargo problems.
1. Container Rain
When temperature changes occur during transportation, moisture can condense on the container ceiling.
Water droplets may fall onto cartons and products.
2. Mold and Mildew
High humidity environments can cause:
- Mold growth
- Bad odors
- Product rejection
This is especially common with:
- Clothing
- Shoes
- Leather goods
- Wooden products
3. Rust and Corrosion
Metal products may develop:
- Surface rust
- Corrosion
- Reduced product quality
Can You Use Too Much Container Desiccant?
Generally, using additional desiccant does not harm cargo.
However, excessive use may:
- Increase shipping costs
- Waste product
- Increase unnecessary packaging expenses
The best solution is not using the maximum amount, but using the correct amount based on actual shipping conditions.
Container Desiccant Recommendations by Industry
Garment and Textile Shipping
Recommended:
- 20ft container: 10–12 strips
- 40ft container: 20–24 strips
Reason:
Textiles easily absorb moisture and can develop mold during long transportation.
Furniture and Wooden Products
Recommended:
- Higher quantity protection
Wood naturally releases moisture, creating additional humidity inside containers.
Electronics Shipping
Recommended:
- Standard container desiccant quantity
- Additional humidity indicators if necessary
Electronics are sensitive to moisture and corrosion.
Food Packaging Materials
Recommended:
- Food-safe desiccants
- Proper certification
Which Container Desiccant is Best for Ocean Shipping?
Different desiccants have different advantages.
Calcium Chloride Container Desiccant
Calcium chloride is one of the most popular choices for ocean shipping.
Advantages:
- Very high moisture absorption capacity
- Works well in high humidity environments
- Suitable for long-distance transportation
- Effective against container sweat
It is widely used for:
- Full container shipments
- Garments
- Furniture
- Industrial products
Silica Gel Desiccant
Silica gel is commonly used for:
- Small packages
- Electronics
- Pharmaceutical products
Advantages:
- Clean
- Non-liquid
- Stable performance
However, for full container moisture protection, calcium chloride desiccants are usually more suitable because of their higher absorption capacity.
Clay Desiccant
Clay desiccants are:
- Natural
- Cost-effective
- Suitable for general moisture control
They are often used where moderate moisture protection is required.
FAQ
How many desiccants are needed for a 20ft container?
Normally, 8–10 strips are recommended. For high humidity shipments, 10–12 pieces may be needed.
How many desiccants are needed for a 40ft container?
Normally, 16–20 strips are recommended depending on cargo type and shipping conditions.
How long does container desiccant last?
Most container desiccants can provide moisture protection for approximately 30–90 days depending on humidity and transportation conditions.
Can container desiccants prevent container rain?
Yes. When the correct quantity is used together with proper cargo loading, container desiccants can significantly reduce condensation risks.
What is the best desiccant for ocean shipping?
Calcium chloride container desiccants are widely considered one of the best choices for ocean transportation because of their strong moisture absorption performance.
Conclusion
Choosing the correct container desiccant quantity is important for protecting goods during ocean transportation.
As a general guideline:
- 20ft container: 8–10 strips
- 40ft container: 16–20 strips
- 40HQ container: 18–24 strips
However, the ideal quantity depends on your cargo type, shipping route, humidity conditions, and desiccant capacity.
SORBSTAR provides high-performance calcium chloride container desiccants designed for international ocean shipping. With strong moisture absorption capacity, convenient hanging design, and customized solutions, SORBSTAR helps exporters protect cargo from moisture damage.
Need help calculating the right container desiccant quantity for your shipment?
Contact SORBSTAR for product recommendations, samples, and bulk pricing.
Recommended Internal Links
- Container desiccant
- Calcium chloride container desiccants
- Best desiccant for ocean shipping
- How to prevent container rain
