What is the ideal bed height? Properly calculate mattress + box spring + legs

You ordered a 25 cm mattress, you have an 18 cm slatted base, and you are still unsure which legs to choose. Or perhaps your mother struggles to get up in the morning, and you are wondering if raising her bed would really make a difference. In both cases, the answer comes down to a simple calculation that no one bothers to explain clearly: mattress + base + legs = total bed height, and this total height is not trivial.

The basic rule: align the top of the mattress with the hollow of the knee

The ergonomic principle is simple. Sitting on the edge of the bed, with your feet flat on the floor, your knees should form an angle close to 90°. This position makes getting up and lying down easier without straining the lower back or hips.

For the vast majority of adults of standard height (between 1.60 m and 1.80 m), this corresponds to a mattress top height between 45 and 55 cm from the floor. Below this, you are too low, and getting up becomes laborious. Above 60-65 cm for a shorter person, the feet no longer touch the ground, and getting into bed becomes uncomfortable.

For seniors or people with reduced mobility, the recommendation is slightly higher: a total height between 55 and 65 cm reduces the strain on the knee and hip joints when getting up, which, in the long term, preserves true autonomy.

With these benchmarks established, let’s see how to achieve them by adjusting the three elements you control.

The three components of total height

The mattress: thickness varies more than you think

An entry-level mattress often measures between 15 and 18 cm. Intermediate models, suitable for the majority of sleepers up to about 85-90 kg, range from 18 to 22 cm. Premium mattresses, particularly hybrids with multiple layers of foam and pocket springs, easily exceed 25 to 30 cm.

This thickness is often the first surprise upon receipt: a mattress advertised as 25 cm looks impressive once placed on the base. This is a factor to note before any purchase, as it directly influences the choice of leg height.

The base: rarely more than 18 to 20 cm (excluding decorative box springs)

A classic slatted base, the most common in France, generally measures 15 to 18 cm in height (frame included, without the legs). It rests on the bed legs.

Decorative box springs, those whose frame is entirely covered in fabric or faux leather, can go further: some models display integrated heights of 25, 30, or even 38 cm — meaning they do not need legs, or only small pads, to reach a reasonable total height.

One often overlooked point: a slatted base placed directly on the floor (without legs) prevents any air circulation under the mattress. Moisture stagnates, promoting mold. Legs are therefore not just a matter of style or height: they also serve an essential hygienic role. A minimum of 10 cm of clearance under the base is generally recommended.

Bed legs: the only truly adjustable parameter afterward

This is where you have control. Bed legs screw under the base frame and come in a variety of heights: 5, 10, 15, 17, 20, 25 cm, and sometimes more.

Legs of 15 to 17 cm are considered “standard”: when combined with an 18 cm base and a 20 cm mattress, you reach a total height of 53-55 cm, in the ideal zone for the majority of adults.

Legs of 20 cm and more allow for sufficient clearance to slide storage drawers under the bed — an interesting option in small spaces. They are also suitable for raising the bedding of an elderly person or someone recovering.

Very low legs (5-7 cm) give a “floor bed” look, contemporary and often associated with Scandinavian or Japanese style. Practical for aesthetics, less so for the knees upon waking.

Making the calculation: a concrete example

Let’s take a typical case: an 18 cm slatted base, a 20 cm foam mattress. Without legs, the total height is 38 cm — too low for most adults. With 15 cm legs, you reach 53 cm: excellent for someone of average height. With 20 cm legs, you reach 58 cm: very comfortable for a tall person, or recommended for a senior.

Another example: premium hybrid mattress of 28 cm on a 20 cm box spring with 10 cm legs. Total height: 58 cm. This is already at the high end of the standard range; for a shorter person, adding taller legs would make no sense.

The formula always remains the same: height of the legs + height of the base + thickness of the mattress = height of the mattress top from the floor. It is this final figure that should be compared to the height of your knee hollow, measurable with a simple measuring tape.

Depending on the profile, priorities change

Tall person (over 1.85 m). The top of the mattress can easily rise to 55-60 cm without inconvenience, and 20 cm legs become natural. The mistake would be to take a very thick mattress (28-30 cm) on 17 cm legs with an 18 cm base: you then approach 65 cm, which forces you to sit on the edge of the bed with your feet not really touching the ground.

Short person (under 1.60 m). The target is rather 44-50 cm. A mattress of 18-20 cm on a 15 cm base with 10-12 cm legs is often sufficient. The low bed, tatami style, can also be suitable if there are no knee problems.

Couple with different body types. We aim for the middle zone. A bed that is too low will be frustrating for the tall person, too high risky for the short one. The 50-55 cm range is generally a good compromise, to be adjusted according to any discomfort felt.

Seniors and people with reduced mobility. This is where height makes a measurable difference in daily life. Between 55 and 65 cm total height, getting up puts much less strain on the knees and hips. If the existing bed is too low, leg risers (accessories sold separately) can increase the height without changing all the furniture.

Height and bedroom style: what is often underestimated

The height of the bed also influences the perception of space. A low bed (40-45 cm mattress top) visually enlarges a small room, gives an impression of a higher ceiling, and integrates well into a clean contemporary interior. A raised bed (55-65 cm) adds volume and presence to the room and naturally creates storage space underneath.

In a studio or a room of less than 12 m², opting for 20 cm legs with a storage drawer is often a decision as practical as it is aesthetic. In a large master bedroom, a high bed with an imposing box spring frame can become the centerpiece of the decor.

What manufacturers do not always clearly indicate

When you buy a base, does the height indicated in the product sheet correspond to the height of the frame alone, or does it include the supplied legs? This is not always specified. Always check if the legs are included in the product and what their height is. Some brands deliver 10 cm legs by default and offer taller legs as a paid option.

On the mattress side, the thickness is generally announced without compression. However, a memory foam mattress can slightly compress under body weight and lose 1 to 2 cm “under load.” This is marginal, but worth keeping in mind if you are really at the limit of a height range.

To go further in choosing your base (type of slats, flexibility, compatibility with your mattress), consult our complete guide to choosing your base .