Bonnell or pocket spring unit: which to choose

The spring unit is the skeleton of a mattress. It determines body support, service life, how the mattress feels during sleep and, to a large extent, the product's cost price. Manufacturers choose between two main designs: the interconnected Bonnell unit and the pocket spring unit. Let's look at how they are built, how they differ and which spring unit to choose for a specific model.

How a Bonnell unit is built

A Bonnell spring unit is a classic interconnected design. The springs are hourglass-shaped (double-cone) and are linked together with helical lacing wire. Around the perimeter, the unit is usually reinforced with a border rod made of thicker wire.

Because the springs are connected, the load spreads across the whole surface: when you press one spring, its neighbours also compress. This creates the characteristic “hammock” effect — the mattress yields in a zone rather than at a single point.

Strengths of Bonnell:

• Affordable cost. A simple design and lower wire consumption make the unit economical.
• Strength and load resistance. The connected structure handles intensive use well.
• Ease of production. The unit is simple to build into a mattress and works well with a range of fillings.
• Good ventilation. There is a large volume of air inside the unit.

Limitations:

• less precise anatomical support;
• motion transfer — if one person turns over, the other feels it;
• with an insufficient insulator layer, the springs can be felt through the surface.

How a pocket spring unit is built

Pocket spring units consist of cylindrical springs, each enclosed in its own nonwoven fabric pocket. The pockets are joined with adhesive or ultrasonic welding, but the springs themselves are not linked to each other.

Each spring works independently and compresses only under the part of the body pressing on it. As a result, the mattress follows the body's contours more precisely.

Strengths of the pocket unit:

• Point support. Shoulders and hips sink deeper, and the spine keeps its natural alignment.
• No “wave” effect. One sleeper's movements are barely transmitted to the other — an important argument for double-bed models.
• Zoning options. Springs of different firmness in different zones (for example 5 or 7 zones) give additional support tuning.
• Quiet operation. With no metal connections between springs, the risk of squeaking is lower.

Limitations:

• higher cost price — more springs and materials;
• more complex to produce, requiring careful work with adhesive and fillings.

Comparison by key parameters

• Number of springs: Bonnell has fewer per square metre; pocket units have higher density, including “multi-pocket” and “micro-pocket” versions with more springs of smaller diameter.
• Body support: Bonnell gives even, zone-wide support; pocket springs give point, anatomical support.
• Motion transfer: noticeable with Bonnell, minimal with pocket springs.
• Durability: both designs are long-lasting with the right choice of wire and fillings; Bonnell is less sensitive to assembly quality.
• Cost: Bonnell is lower, pocket units are higher.
• Segment: Bonnell for budget and contract; pocket springs for mid-range and premium.

Check the exact parameters of a specific unit (wire gauge, height, number of springs) on the product card or ask a manager.

Which to choose for your model

When to choose Bonnell

• Budget ranges for the mass market.
• Contract supply: dormitories, holiday camps, hostels, worker accommodation — where reliability and price matter.
• Children's and teen models with a firm filling.
• Sofas and upholstered furniture — Bonnell is still widely used in furniture.

When to choose pocket springs

• Mid-range and premium segment, where buyers expect anatomical support.
• Double mattresses — motion isolation becomes a key advantage.
• Hotel mattresses for 4–5 star properties.
• Orthopaedic and zoned models.

Fillings and fabric: turning a unit into a finished mattress

A spring unit only works in combination with the right layers:

• Insulator layer above the springs — firm fillings (coconut coir, felt, spunbond) stop the springs from pushing through the soft layers.
• Comfort layer — foam, latex, soft mattress fillings.
• Cover — the fabric is chosen to match the model's character. Jacquard is often used for Bonnell in the contract segment, and double jacquard or heavy knit for premium pocket spring models. Read more in “Double jacquard or knit” and in our guide “How to choose mattress fabric”.

Practical tips for buyers

• Calculate the full cost. The price difference between units is only part of the equation: a pocket unit may need different fillings and adhesive, while Bonnell may need a denser insulator layer.
• Check dimensions. Units are produced for standard mattress sizes; confirm non-standard sizes in advance.
• Check geometry. On acceptance, assess how flat the unit is, the strength of the border rod and the quality of the connections.
• Think about logistics. Spring units take up a lot of space; ask a manager about packaging format and delivery terms.

The Bonnell unit is a reliable, economical solution for the budget and contract segments. The pocket spring unit is the choice for models where anatomical support, quietness and motion isolation matter. Many manufacturers keep both types in their range to cover different price niches.

AIES supplies spring units and other mattress components to manufacturers across Kazakhstan and Central Asia. Contact us to check availability, request a price list and choose the right unit for your model.