1D vs 15D: What's the Difference and How to Choose

Denier determines a fiber's softness, volume and price. We break down how 1D differs from 15D and which one fits your product.

Denier (D) is a unit that indicates the thickness of an individual fiber. In a polyester filling lineup you'll most commonly see four options: 1D, 3D, 7D and 15D. The difference between them affects the softness, volume and final price of your finished product.

1D — premium softness

1D is the finest fiber in the lineup. It gives the softest, most delicate texture and is most often used where the filling touches skin or needs to feel especially gentle: decorative pillows, premium soft toys, the top layer of furniture cushions. It's also the most expensive option in the lineup.

15D — maximum volume

15D is the thickest fiber. It feels firmer to the touch but delivers the most volume and resilience, holding its shape under load for longer. It's the optimal choice for mattress base layers, the frame parts of large furniture, and technical filling — anywhere structure matters more than softness. It's also the most affordable option in the lineup.

3D and 7D — the middle ground

3D and 7D sit between 1D and 15D. 3D is closer to 1D in softness but slightly more resilient and voluminous — a versatile choice for sofas, armchairs, blankets and medium-sized toys. 7D leans closer to 15D: it delivers noticeable volume while keeping a comfortable softness, and works well for mattress mid-layers and large upholstered furniture.

How to choose

• If softness and a premium feel are the priority: 1D.
• If you need a balance of softness and price for furniture and textiles: 3D.
• If volume matters while keeping comfort — for example, mattresses: 7D.
• If the priority is maximum volume and price, not softness: 15D.

All four options in our lineup are siliconized and spiral, so the difference between them comes down purely to fiber thickness, not the base treatment. If you're not sure which one fits your product, send us the specs and we'll match a denier to the job.