Foam 101: 5 Key Terms to Know Before Buying

To help you navigate your options, we’ve put together this guide to the most important foam terms. Understanding these concepts will empower you to choose the perfect foam for any indoor or outdoor cushion project.

5 Important Foam Terms to Know

Foam Density: The #1 Indicator of Longevity

Foam density refers to the weight of the foam in pounds per cubic foot (PCF). It’s a measure of how much material (vs. air) is packed into the foam. This is the most important factor in foam durability. A high-density foam will last for years, while a low-density foam will break down and "bottom out" quickly.

Here’s a breakdown of our new density classifications:

• Low Density (Below 1.3 PCF): Best for non-seating uses like packaging, craft projects, or very light-use back cushions.
• Medium Density (1.3 - 1.8 PCF): Suitable for back cushions or very occasional-use seat cushions.
• High Density (1.8 PCF or higher): This is our standard for quality seat cushions. All CushionRite® seating foams (Antimicrobial, Upholstery, Premium, and High Resilience) meet or exceed this high-density minimum.

IFD (Indentation Force Deflection): Foam Firmness Rating

Indentation Force Deflection (IFD) measures how firm or soft the foam feels. It’s determined by the force required to compress a foam sample.

Do not confuse density with firmness. You can have a high-density (durable) soft foam (low IFD), and a low-density (non-durable) foam that is firm (high IFD). Always choose density first (for longevity), then IFD (for comfort).

• Extra Soft (10-15 IFD): For back cushions and mattress toppers.
• Soft (16-25 IFD): For softer seat cushions or back cushions.
• Medium (26-35 IFD): The most common choice for standard seat cushions.
• Firm (36-45 IFD): For firmer seating and high-use areas.
• Extra Firm (46-60 IFD): For bench seating and supportive cushions.
• Firmest (61+ IFD): For structural support or very firm seats.

Choose the firmness level based on comfort preference and intended use. Firmer foam is generally better for seating support, while softer foam can work well for backrests or headboards.

Antimicrobial Foam: Ideal for Outdoor Cushions

Antimicrobial foam includes additives that actively inhibit the growth of mold, mildew, and bacteria — a must for foam used in damp environments like boats, RVs, or patios.

Most polyurethane foam does not drain easily, so antimicrobial protection helps extend its lifespan and keeps cushions fresh. Just look for “Antimicrobial” in the product title, like with CushionRite® Antimicrobial Cushion Foam.

Reticulated Foam: Best for Water Drainage

You’ll often see the term "reticulated" used to describe open-cell foam with excellent airflow and drainage. This type of foam has its cell walls "blown out," creating a breathable, porous structure ideal for marine and outdoor settings.

Sailrite’s CushionRite® Dry Fast Antimicrobial Foam is the perfect example. Water flows directly through it, allowing it to dry almost immediately. It's the top choice for patio furniture, cockpit cushions, and any seat that gets wet.

Foam Usage: Occasional vs. Frequent Use

At Sailrite, we make it easy to narrow your options by usage type:

• Occasional Use: Weekend boaters, patio cushions and formal living room furniture.
• Frequent Use: Family room sofas, daily-use chairs, or full-time cruiser settees.

Choosing the correct foam grade based on use frequency will help your cushions hold their shape and support for years to come.

Shop Cushion & Upholstery Foam

To continue learning more about foam, head over to the next post in our foam series, “Comparing Types of Upholstery Foam.”