Coil Sprung Mattresses: The Facts

Construction

Coil sprung mattresses use a wire coil system inside the mattress, covered with padding and ticking fabric. There are three main coil designs:

• Hourglass coils: the most common type, found in less expensive mattresses. The coil narrows in the middle and flares at the top and bottom.
• Pocketed coils: each coil is individually wrapped in a fabric pocket. Although the pockets are connected, the coils move independently, which means less motion transfer between sleepers.
• Continuous coils: a single length of wire is shaped into a series of S-shaped loops. The thinking behind this design is that connecting every coil provides more stability and distributes weight more evenly.

Three technical factors affect performance:

• Gauge: the thickness of the wire. Counter-intuitively, a higher gauge number means thinner wire. Thinner coils (e.g. gauge 16.5) produce a softer feel; thicker coils (e.g. gauge 12.5) produce a firmer mattress.
• Working turns: how tightly the coil is wound. More turns mean a softer, longer-lasting mattress because the load is spread across a larger spring surface.
• Tempering: the process of heating and cooling the coils to help them hold their shape over time. Double-tempered coils go through this process twice for greater durability.

Spring Count

A typical coil mattress contains between 250 and 1,000 coils. As a rough guide:

• Single: around 300 coils
• Double: around 375 coils
• King: around 450 coils

A higher spring count does not automatically mean a better mattress. The quality of the steel, the gauge, and the comfort layers on top all play a role. For a detailed comparison with pocket sprung models, see our pocket sprung guide.

Advantages

• Price: coil sprung mattresses are one of the most affordable types available. There is a model to suit most budgets.
• Breathability: the open coil structure allows air to circulate freely, helping to keep the sleeping surface cool. Unlike memory foam, coil mattresses do not retain body heat.
• Availability: they are the most widely stocked mattress type in UK shops, making them easy to test in person.

Disadvantages

• Durability: coil mattresses can begin to sag earlier than other types, particularly cheaper models. Turning and flipping the mattress regularly helps extend its life.
• Allergies: the fibres and padding used in coil mattresses can harbour dust mites, offering less allergy protection than foam or latex alternatives.
• Noise: the coils can squeak or creak with movement, which is more noticeable in lower-quality models.
• Motion transfer: when one person moves, the connected coils transmit movement across the whole mattress. Pocketed coil designs reduce this, but open coil models transfer motion freely.

Firmness And Sleeping Position

A common assumption is that firmer coil mattresses provide better back support. In practice, this depends on your sleeping position. Most people sleep on their sides, and side sleepers generally need a mattress that moulds to the body's curves to keep the spine aligned. Individually wrapped (pocketed) coils are the best option here.

For help choosing the right firmness level for the way you sleep, see our firmness guide.