Why Your Insoles Don’t Fit: A UK Guide to Shoe Insole Sizing and Fitting

Have you bought new insoles only to find they are too long, too wide, too narrow or slipping inside your shoes? You’re not alone. The right insole needs to fit both your foot and your footwear.

Shoe sizes can vary between brands and styles, so choosing your usual UK size does not always guarantee a perfect fit. This guide explains how to check insole sizing, trim suitable insoles and choose shoes that accommodate orthotic support.

4 Common Insole Fitting Problems

1. Insoles are too long

If the toe area curls or bunches up, the insole may be too long for your shoe. Check the fit before trimming.

2. Insoles are too short

A short insole may leave part of your foot unsupported. Check the manufacturer's size guide and measure against your existing shoe liner before ordering.

3. Insoles are too narrow or wide

An insole that moves from side to side can feel unstable. Choose a suitable width and check that the insole sits flat without folding against the shoe.

4. Your shoes lack enough space

Even correctly sized insoles can make shoes feel tight if the footwear has insufficient depth or width. Shoes with removable liners and secure fastenings are often easier to fit.

How to Fit Shoe Insoles Correctly: 3 Simple Steps

Step 1: Check your shoe

Remove the existing liner if it is designed to be removable. Check the available length, width and depth before inserting your new insoles.

Step 2: Compare and trim carefully

For trim-to-fit insoles, use the removable shoe liner as a template, aligning the heel and marking the toe shape. Trim small amounts at a time, following the manufacturer's instructions.

Important: Do not cut custom-moulded or prescribed orthotics unless your provider confirms they can be trimmed.

Step 3: Test the fit

Place the insole flat inside the shoe. Check for raised edges, folds, movement or pressure around your toes. Try both shoes indoors and make sure your feet feel secure.

NHS podiatry services publish similar insole fitting guidance, including using a shoe liner as a template when trimming suitable insoles. See the Podiatry Services fitting guide.

Which Shoes Work Best with Orthotic Insoles?

When choosing footwear for orthotic insoles, look for:

• Adequate depth and width to accommodate your foot and the insole.

• A removable liner, where appropriate.

• A secure fastening, such as laces or adjustable straps.

• A firm, supportive heel area.

• Enough toe room to prevent rubbing or pressure.

Take your orthotics with you when buying new shoes. A shoe that fits without an insole may feel too tight once the insole is added.

When Should You Stop Wearing Your Insoles?

Your insoles should not cause significant pain or damage your skin. Stop using them and seek advice from your podiatrist or healthcare professional if you develop persistent redness, blisters, sores, rubbing or worsening discomfort.

If your orthotics were prescribed, contact your provider before changing their shape or fit.

Find the Right Fit with RS Orthotics

At RS Orthotics Insoles, we understand that comfortable support starts with the right fit.

Before choosing your next pair, check your shoe dimensions, review the sizing information and consider whether your footwear has enough room for the insole you need.

Explore our range at RS Orthotics Insoles and choose the support that suits your footwear and individual requirements.

RS Orthotics — better fitting starts with informed choices.