The shoe is decided before the insole, whether or not anyone says so. Volume, last shape, heel counter and the removable footbed set the limits within which a device can exist, and a specification written without them is a design for a foot that has nowhere to live.
Clinics and distributors both tend to regard footwear as the client’s business, which is understandable and expensive: a large share of remake requests trace back to a shoe that was different from the one everyone imagined.
This article describes how to read a shoe before writing an insole specification, which measurements matter, and how to record them so that the factory can build against them rather than against an average.
Four properties of a shoe that constrain a device
The first is internal volume: how much space exists above the footbed. A device occupies that space, and a shoe with limited volume will either accept a thin device or refuse a thick one, regardless of what the design would prefer.
The second is the last shape: how the shoe curves, where the widest point sits, and how the toe box tapers. A device built on a straight last placed in a curved shoe will lift at the edges or sit crooked, and the client will describe it as uncomfortable without being able to say why.
The third is the heel counter: how tall and how stiff. A deep, firm counter holds a device in place; a soft, low one allows movement, which changes how the device behaves under load. This is the property most often ignored and the one most often responsible for a device that feels different after a week.
The fourth is the footbed. If it is removable, the device replaces it and inherits its space; if it is glued in, the device sits on top and needs volume that may not exist. Asking the client to lift the footbed and photograph it takes seconds and prevents a category of failure.
A useful habit is to ask the client to bring the shoes they wear most, not the shoes they like most. The two are often different, and the device will spend its life in the first.
It is worth asking, early, whether the client has more than one pair in use. Clients who alternate between shoes often describe the device as inconsistent when the device is behaving identically and the shoes are not. Knowing that two pairs are in play turns a confusing report into a straightforward comparison, and it usually takes one question at the start rather than five at the follow-up.
How to read a shoe in two minutes
Open the shoe and look inside. Note the length of the footbed, the width at the ball, and whether the surface is flat or shaped. A shaped footbed means the device has to either match the shape or replace it, and the choice affects thickness.
Press the heel counter from both sides. A counter that resists thumb pressure will hold a device; one that yields will not. Note also its height relative to the client’s heel, because a low counter combined with a thick heel cup produces pressure at the top edge.
Flex the shoe at the ball. A shoe that flexes easily will work with a flexible device and fight a rigid one; a stiff shoe will accept a rigid device and make a soft one redundant. The flex point should coincide with the client’s ball of foot, which is a two-second check with the shoe against the sole of the foot.
Then photograph the shoe from above and from the side, with the footbed removed if possible. Two photographs stored with the record answer most of the questions a factory would otherwise have to ask, and they cost less than a remake.
It helps to keep a small reference set of shoes in the clinic: one deep walking shoe, one low-profile trainer, one safety boot. When a client’s shoe is ambiguous, comparing it with a known reference takes seconds and produces an answer the factory can use. Three pairs of shoes on a shelf are, in this narrow sense, a measuring instrument.
Matching device thickness to volume
Thickness is the variable that most directly trades off against the shoe. A thicker device provides more separation and more cushioning; it also raises the foot inside the shoe, which changes how the heel sits in the counter and how the laces close.
The practical approach is to start from the available volume rather than from a preferred thickness. Measure the depth at the heel and at the instep with the footbed removed, then choose the thickest device that still leaves room for the foot to sit without pressure on the top of the toes.
Where volume is limited, the design moves rather than the thickness: a posted device can be thinner under the arch and still provide support, and a cover change can alter the feel without adding height. That is a conversation with the designer, and it is much easier if the volume numbers are on the form.
For distributors building a range, defining thickness envelopes per shoe class is more useful than defining styles. A range organised by volume sells predictably; a range organised by appearance creates returns that nobody can explain.
Where volume is genuinely tight, a shorter device is often the better answer than a thinner one. Length can be reduced without losing the features that matter; thickness cannot be reduced without losing separation, and a device that has been thinned to fit has usually lost the property it was ordered for.
Where a client wears orthotics in boots or safety footwear, the volume question becomes the dominant one. These shoes are usually built for protection rather than for depth, and a device that fits a walking shoe will often sit too high in a safety boot. Asking for the boot as well as the shoe is a small request that prevents a pair from being built twice.
When the shoe is the wrong shoe
Sometimes the answer is a different shoe. A client who wants a firm device inside a soft, shallow trainer is asking for a combination that will not work, and the honest response is to say so before the order rather than after.
This is easier to say when the conversation starts with the shoe. A clinic that checks footwear first can recommend a shoe change as part of the plan, which is often cheaper for the client than a compromise device that satisfies nobody.
For distributors and retailers, the same logic applies in reverse: a shoe range that pairs naturally with the insole range reduces support calls. That is a merchandising decision, and it is worth making deliberately rather than discovering through complaints.
The commercial upside is real. Clients who are told plainly that their shoe limits what can be built tend to trust the recommendation more, not less, because the recommendation is visibly about them rather than about the sale.
It is worth separating the shoe the client wears for the activity from the shoe the client wears for the appointment. A runner who arrives in a smart shoe and trains in a neutral trainer has given the clinic two different sets of constraints, and a device built for the wrong one will be worn in the wrong shoe. Asking which shoe the device is for, and writing the answer on the order, is a two-second habit that removes a category of disappointment. Where the client uses several pairs, build for the most demanding one and say so, because a device that fits the tightest shoe will fit the others and the reverse is not true.
Where the volume is unknown and the client cannot provide the shoe, say so on the order. An explicit gap is manageable; an assumed one is not. Factories build better from a form that admits a missing field than from one that fills it with a guess, because the first prompts a question and the second produces a pair.
Recording footwear so the factory can build against it
The minimum record is four fields: shoe type, size, whether the footbed is removable, and a photograph. Add the internal length if it can be measured, and the heel counter height if it is unusual. Six fields, filled in once, answer most production questions.
Shoe type should be described in plain words rather than brand names: walking shoe, running shoe, court shoe, safety boot, school shoe, sandal. Brand names change and mean different things in different markets, while a plain description travels.
The photograph should include the footbed if it comes out, because the shape of the footbed tells the factory more about the internal volume than a description can. A photograph taken on a phone is sufficient; the purpose is shape, not resolution.
These fields belong in the same record as the foot measurement, not in a separate email. A specification that has to be assembled from three sources is a specification that will be assembled incorrectly on a busy day.
Photographs should be taken in the same way each time: one from above with the footbed in place, one with it removed, one from the side. Three images, consistent between clients, make a library that a clinic can actually use.
Footwear in the follow-up conversation
The follow-up is where footwear shows up again, because the client has usually been wearing the device in the shoe they actually own rather than the one described at the consultation. That difference is the most common explanation for a device that felt fine in the room and less fine at home.
Ask at the follow-up which shoe the device has been worn in, and how many hours a day. Two questions that take ten seconds and explain most of what the client is about to describe.
If the shoe has changed, the device may still be right and the context wrong. Writing that down matters, because the next order should be built for the shoe the client actually wears rather than the one that was discussed.
Over a few years this produces something valuable: a record of which shoes work with which devices for which clients. That record is the clinic’s own evidence base, and it is built from fields that cost almost nothing to collect.
It is worth noting how often the follow-up reveals a shoe that was never mentioned. Clients rarely think of footwear as part of the order, and a question at the start of the consultation is cheaper than a question at the end of the follow-up. Two words, which shoes, asked early, change the quality of the whole record.
A checklist before the specification is signed
Before signing, confirm five things: the shoe has been seen, the volume has been considered, the thickness has been chosen against that volume, the footbed situation is known, and the client understands what the device will and will not do in that shoe.
The last item is the one that prevents disappointment. A device built to a specification is a device with a purpose, and the client should know what that purpose is before they leave the room rather than discovering it through use.
Keep the checklist with the order. When a remake question arises, the checklist turns a conversation about opinion into a conversation about evidence, and evidence is what makes a remake policy workable rather than adversarial.
None of this is technical. It is a habit of looking at the shoe before designing for the foot, and it is the cheapest quality measure available to any clinic or distributor in this category.
The checklist also protects the factory. A buyer who can show that the shoe was seen and the volume considered is a buyer whose remake request can be assessed quickly, and speed in that conversation is worth as much as the outcome.
Frequently asked questions
Do you need the shoe to build an insole?
We need to know about the shoe. A photograph, the shoe type, the size and whether the original footbed is removable are usually enough to build against. Two lines on the order form prevent most volume-related remakes.
What if the client's shoe has no removable footbed?
Then the device sits on top of the existing footbed and needs volume that may not exist. We will say so before production, and the design may need to be thinner or the shoe may need to change.
Can one device be used in several shoes?
Sometimes, and it depends on volume. A device built for a deep walking shoe will not necessarily sit in a low-profile trainer. Tell us the shoes the client intends to use and we will build for the most demanding one.
How thick should an insole be?
Start from the available volume rather than from a preferred thickness. The thickest device that still leaves room for the foot to sit without pressure is the right answer, and it differs by shoe.
What is the minimum order?
Two hundred pairs for insoles, mixed across styles and sizes. Samples leave within three days of confirmation so the process and the materials can be checked before a volume order.
What happens if the device does not fit the shoe?
If the specification recorded the shoe and the device does not match it, that is our cost. If the shoe turned out to be different from the one described, we work from photographs and the shoe reference to propose a solution.
What certification applies?
European Union certification and ISO quality system certification. That is the full scope of the documentation we hold, and the documents are sent on request.
What we would do next
If you are writing a specification, send the shoe photographs with the foot record. The insole categories page shows the ranges we build, the factory page shows where they are made, and the FAQ page states minimums, samples and transit in writing. Contact us with the shoe type and we will describe the volume envelope.
For related reading, see how the shoe sets the limits of the insole and where two supply chains meet.
This article is intended for professional and educational reference. It is not medical advice. Foot assessment equipment produces measurements and images; clinical interpretation and any decision about care remain the responsibility of a qualified professional. Certification scope is limited to the documentation we hold: European Union certification and ISO quality system certification.