Carpet Pad Thickness Calculator
Convert carpet pad thickness to comfort rating, durability, and recommended use.
Compare foam, rubber, and fiber pad types.
Select your carpet type and traffic level to find the ideal pad thickness and density.
Understanding Carpet Pad Selection
Carpet padding (also called underlay or cushion) sits between the carpet and the subfloor. It dramatically affects how the carpet feels underfoot, how long it lasts, and how well it insulates sound and temperature. The two key specifications are thickness and density. Thicker is not always better because excessively thick padding can cause carpet to wrinkle and buckle, especially with certain carpet types.
Pad Thickness Guidelines:
| Pad Thickness | Metric | Comfort Level | Best For |
|---|---|---|---|
| 1/4 in (6 mm) | 6.4 mm | Firm | Commercial, Berber carpet, low-pile |
| 3/8 in (10 mm) | 9.5 mm | Medium | Most residential, cut-pile carpet |
| 7/16 in (11 mm) | 11.1 mm | Medium-plush | Living rooms, bedrooms |
| 1/2 in (13 mm) | 12.7 mm | Plush | Bedrooms, low-traffic areas |
| 5/8 in (16 mm) | 15.9 mm | Very plush | Luxury bedrooms only |
Pad Density by Material:
Density is measured in pounds per cubic foot (lb/ft³) or kilograms per cubic meter (kg/m³). Higher density means better support and longer life.
- Rebond foam (most common): 5 to 10 lb/ft³ (80 to 160 kg/m³). Budget-friendly and widely available. Choose at least 6 lb/ft³ for residential use.
- Memory foam: 3 to 5 lb/ft³ (48 to 80 kg/m³). Very comfortable but less durable for high-traffic areas.
- Waffle rubber: 60 to 120 oz/yd² flat rubber. Extremely durable, often used in high-end residential and commercial applications.
- Fiber pad (felt or jute): 28 to 40 oz/yd². Traditional material, firm underfoot, good for patterned Berber carpet.
- Flat rubber: 16 to 22 lb/ft³ (256 to 352 kg/m³). Most durable option, highest cost, recommended for heavy commercial traffic.
Matching Pad to Carpet Type:
This is critical and often overlooked. Using the wrong pad thickness can void your carpet warranty.
- Cut pile (plush, frieze, Saxony): Use 3/8 to 7/16 inch (10 to 11 mm) pad with density of 6 to 8 lb/ft³.
- Loop pile (Berber): Use 1/4 to 3/8 inch (6 to 10 mm) FIRM pad with density of 8 lb/ft³ or higher. Thick, soft pads cause Berber carpet to stretch and wrinkle.
- Cut-loop (pattern): Use 3/8 inch (10 mm) pad with density of 6 to 8 lb/ft³.
- Commercial carpet: Use 1/4 inch (6 mm) flat rubber or high-density rebond.
Sound and Thermal Insulation:
Carpet padding is an excellent sound insulator. Thicker, denser pads reduce impact noise (footsteps) by 15 to 25 decibels. For thermal insulation, padding adds an R-value of 1.0 to 2.5 depending on thickness and material. This can reduce heating costs in rooms above unheated spaces like garages or basements.
Practical Tip:
When replacing carpet, always replace the padding too. Old padding compresses and loses its cushioning ability. Reusing old padding under new carpet will make the new carpet feel flat and wear out faster. Budget approximately 3 to 5 dollars per square foot (30 to 55 dollars per square meter) for quality residential padding installed.