Heel Lifts for Leg Length Discrepancy: A Guide to Choosing the Right Height

If you've been told that one leg is shorter than the other, a heel lift or shoe lift may be recommended to help compensate for the difference.

But knowing you have a leg length discrepancy is only part of the picture. One of the most common questions is:

What height heel lift do I actually need?

Heel lifts are available in different heights, commonly including 4mm, 6mm, 8mm and 10mm. Choosing the right height isn't simply a matter of matching the lift to what you think your leg length difference might be.

The size and type of discrepancy, your footwear and how much correction has been recommended all need to be considered.

What Is a Leg Length Discrepancy?

A leg length discrepancy (LLD) means that one lower limb is shorter than the other.

Small differences in leg length are relatively common and don't necessarily cause problems. The American Academy of Orthopaedic Surgeons notes that subtle differences occur in more than half of people and that minor differences are often well tolerated.

Leg length differences can occur for a variety of reasons, including differences in bone length, previous injury or fracture, growth-related conditions and other musculoskeletal factors.

You may also hear the terms leg length inequality, limb length discrepancy or leg length difference used to describe the condition.

Structural vs Functional Leg Length Difference

Not every apparent leg length difference means that the bones of one leg are physically shorter.

A structural or anatomical leg length discrepancy occurs when there is an actual difference in the length of the bones of the lower limbs.

A functional leg length difference can occur when other factors make one leg appear or function as though it is shorter, even without the same anatomical difference in bone length.

This distinction matters because simply adding a heel lift isn't necessarily appropriate for every apparent leg length difference.

If you haven't been formally assessed, it's better to establish what is causing the difference before trying to correct it yourself.

How Are Leg Length Differences Measured?

There are several ways a health professional may assess leg length.

A common clinical approach is the block test, where blocks of known heights are placed beneath the shorter side while standing until the pelvis is level.

A systematic review examining different measurement techniques concluded that the block test appears to be one of the more useful clinical assessment methods, while full-length standing radiography provides a more valid and reliable method for measuring an anatomical leg length discrepancy.

This is one reason we don't recommend trying to determine a precise heel lift height simply by looking in a mirror or measuring your legs yourself.

How Do Heel Lifts Help With a Leg Length Discrepancy?

A heel lift sits beneath the heel of the shorter side and provides additional height inside the shoe.

For example, if you've been professionally assessed and advised to use a 6mm heel lift, the lift provides that additional height beneath the heel.

For relatively small differences, an internal lift can be a simple and removable option. The AAOS includes shoe lifts among the non-surgical approaches that may be considered for smaller limb length discrepancies.

However, a heel lift doesn't physically lengthen the leg. It is being used to accommodate or compensate for some of the difference while you're wearing your shoes.

What Height Heel Lift Do I Need?

This is where it's important not to apply a one-size-fits-all formula.

If a podiatrist, physiotherapist, orthotist or other health professional has assessed you and recommended a specific lift height, that recommendation should be your starting point.

For example:

However, having a measured 10mm leg length difference doesn't automatically mean everyone with that measurement should purchase a 10mm heel lift.

Research has not established a single universally accepted threshold for when a leg length difference should be corrected or exactly what proportion of the difference should be corrected.

That is why professional assessment becomes particularly important when you don't already know the lift height you require.

Should You Correct the Full Leg Length Difference?

Not necessarily.

It can be tempting to assume that if one leg measures 8mm shorter, the solution must be an 8mm lift.

In practice, deciding how much correction is appropriate is more individualised.

A systematic review of shoe lifts for adults with leg length discrepancy found some evidence of improvements in pain and function, but the researchers also highlighted the lack of good-quality evidence establishing how much of a discrepancy should be corrected.

For this reason, we recommend following the height prescribed or recommended to you rather than attempting to calculate the correction yourself.

Should a Heel Lift Go in One Shoe or Both?

When a heel lift is being used specifically to compensate for a leg length discrepancy, it is generally placed in the shoe on the shorter side.

This is different from some other uses of heel lifts.

For example, heel lifts may sometimes be used in both shoes for Achilles tendon conditions, where the aim isn't to correct a difference between the lengths of the legs.

So before ordering a single heel lift or a pair, consider why you're using the lift.

Heel Lift Height and Heel Lift Size Are Different

This is an easy detail to overlook when shopping online.

Height tells you how much elevation the heel lift provides – for example, 4mm, 6mm or 8mm.

Size generally relates to the physical dimensions of the lift and the shoe size it is designed to fit.

So you might need, for example:

Medium size + 6mm height

rather than simply ordering a “6mm heel lift”.

Always check both the height and sizing information on the individual product before ordering.

What Type of Heel Lift Is Best for Leg Length Discrepancy?

Heel lifts are available in materials including EVA, foam, Poron, gel and silicone.

When you're trying to achieve a specific amount of elevation, firmness is worth considering as well as comfort.

A very soft material can compress more beneath body weight, whereas a firmer EVA heel lift generally provides a more stable raise.

Softer foam, Poron, gel and silicone products may provide additional cushioning, but the best choice depends on the purpose of the lift, your footwear and the amount of elevation required.

If you've already been successfully using a particular type and height, replacing it with a similar product is often the simplest option.

Will a Heel Lift Fit in Any Shoe?

Not necessarily.

Because the heel lift sits inside the shoe, it raises your heel closer to the top of the heel counter.

Smaller lifts can generally be accommodated more easily, while higher lifts require more room.

Heel lifts tend to work best in:

runners and athletic shoes walking shoes lace-up casual footwear work shoes and boots other enclosed shoes with adequate depth and a secure heel.

If your heel starts slipping out of the back of the shoe after inserting the lift, the shoe may not have enough depth for that particular lift.

What If I Need a Larger Shoe Lift?

There is a practical limit to the amount of height that can comfortably be placed underneath the heel inside a shoe.

As lift height increases, it takes up more shoe space and changes the position of the foot within the shoe.

For larger discrepancies, a health professional may recommend a different solution, such as a full-length lift or an external modification to the shoe, rather than placing an increasingly high lift beneath the heel.

The appropriate approach depends on the size and cause of the discrepancy and the individual.

Can Heel Lifts Help With Pain Caused by a Leg Length Difference?

There is some evidence that shoe lifts may help people who have a leg length discrepancy associated with painful musculoskeletal conditions.

A systematic review of adults found low-quality evidence that shoe lifts may reduce pain and improve function. However, the researchers emphasised that better-quality studies are needed, particularly to determine who is most likely to benefit and the amount of correction that should be used.

So it's more accurate to think of a heel lift as a tool that may be useful when appropriately selected, rather than assuming that correcting every small leg length difference will resolve pain.

How Do I Know If I Have a Leg Length Discrepancy?

You may notice differences in the way you stand or walk, but these observations alone aren't enough to determine whether you have a true anatomical leg length difference or how large it is.

If you suspect a discrepancy and haven't previously been assessed, a podiatrist, physiotherapist, orthopaedic specialist or other suitably qualified health professional can assess your lower limbs and determine whether further measurement is appropriate.

This is particularly worthwhile before purchasing a substantial heel lift or attempting to correct a difference yourself.

Choosing a Heel Lift

If you already know the height you've been advised to use, choosing a heel lift becomes much simpler.

Look for:

The correct height – such as 4mm, 6mm, 8mm or 10mm.

The correct size – check the manufacturer's sizing against your footwear.

Appropriate firmness – particularly when the lift is being used to provide a measured amount of elevation.

Suitable footwear – make sure there is enough depth to accommodate the lift without causing heel slippage.

Comfort and stability – the lift should sit securely beneath the heel and feel stable during walking.

If you already know the height you need but aren't sure which product is most suitable, browse our range of heel lifts to compare the different heights, materials and sizes available.

Shop our range of Heel Lifts →

FAQs: Heel Lifts for Leg Length Discrepancy

What is the best heel lift for a leg length discrepancy?

There isn't one heel lift that's best for everyone. The most important considerations are the height you've been advised to use, the firmness of the lift, its size and whether it fits securely inside your footwear.

How much leg length discrepancy should be corrected?

There isn't a universally agreed amount or percentage that should be corrected in every person. Research has identified this as an area where stronger evidence is still needed. If you don't already have a recommended correction, professional assessment is advisable.

Which shoe does a heel lift go in for a leg length difference?

When correcting a leg length discrepancy, the heel lift is generally placed inside the shoe on the shorter side.

Can I measure my leg length difference myself?

Home measurements may give you an indication that something is uneven, but should not be used to determine the amount of correction that is needed. Clinical assessment is necessary to determine an accurate measurement, while imaging can also be used when more precise anatomical measurement is required.

Is a heel lift the same as a shoe lift?

The terms are sometimes used interchangeably, but they can describe different products. A heel lift raises primarily the heel, while a shoe lift may refer to a larger or full-length internal lift or an external modification to the shoe.

Can I use two heel lifts to make a higher lift?

Stacking separate heel lifts isn't generally the best way to achieve a larger correction unless you've specifically been advised to do so. It can take up considerable room inside the shoe and may affect stability. Larger corrections may require a different type of lift or shoe modification.