3/4 Length vs. Full Length Insoles: How to Choose by the Shoes You Wear
The right insole length depends less on your feet than on your shoes. Here is a simple way to choose, shoe by shoe.
Most people pick an insole by thinking about their feet. For length, it is better to think about your shoes. The same arch can feel great in a roomy sneaker and terrible in a slim loafer, simply because of how much space there is inside.
What is the difference?
Full length insoles
A full length insole runs the whole length of the shoe, from heel to toe. It is designed to replace the insole that came with the shoe. You take the original out and put the new one in its place.
3/4 length insoles
A 3/4 length insole covers the heel and arch and ends before your toes. It is designed to sit on top of the shoe’s existing insole, which is handy when that insole is glued in or when there is little room inside.
At CustomSole, both lengths get the same custom arch from your scan and cost the same, $69.99 a pair. Full Length is available now. 3/4 Length is coming soon. You also choose a US shoe size. The scan does not recommend one. The length still depends on the shoes you plan to wear.
Three questions that decide it
1. Does the shoe’s insole come out?
Reach into the shoe and lift the insole at the heel. If it comes out, the shoe can take a full length insole. If it is glued down, a full length pair would sit on top of it and take up too much room, so 3/4 is the better choice.
2. How much room is inside?
Running shoes, walking shoes, hiking shoes and most work boots are built with space for a removable insole. Dress shoes, ballet flats, loafers and fashion sneakers usually have much less. Even if you can pull the insole out, a thin dress shoe may not have the depth for a supportive full length pair.
3. What shape is the toe box?
The toe box is the front of the shoe, where your toes sit. AAOS advises that there should be enough room to wiggle your toes and about half an inch between your longest toe and the end of the shoe. If a full length insole lifts your toes up into a narrow or pointed toe box, switch to 3/4 so your toes keep their room.
Which length for which shoes
| Shoe | Usually best | Why |
|---|---|---|
| Running and walking shoes | Full Length | Removable insole and room inside |
| Everyday sneakers | Full Length | Most have a removable insole |
| Work boots and hiking boots | Full Length | Deep enough for a full insole |
| Court and training shoes | Full Length | Removable insole; check the fit at the toes |
| Dress shoes and oxfords | 3/4 Length | Insole often fixed; little depth |
| Loafers and slip-ons | 3/4 Length | Snug fit; a full insole can lift your heel out |
| Flats and low-profile sneakers | 3/4 Length | Very little room inside |
| Cycling shoes | Often neither | AAOS notes they fit snugly, without room for inserts |
These are starting points, not rules. Two pairs of sneakers can be built very differently, so always check the insole and the toe box of the actual shoe.
How to fit a full length pair
- Take the original insole out of the shoe.
- Slide the new insole in and push the heel all the way to the back.
- Check the toe end. If it curls up or bunches, it needs a trim.
- Lay the old insole on top as a guide and trim the toe end a few millimeters at a time with sharp scissors. Try it in the shoe after each cut.
You choose a US shoe size on the product page. The scan does not recommend one. That size is the outline, and the arch comes from the scan after you pay. A light trim at the toe is sometimes needed. Our size guide compares the men's and women's labels.
How to fit a 3/4 length pair
- Leave the shoe’s own insole in place.
- Set the 3/4 insole on top and push it back until the heel cup meets the back of the shoe.
- Put the shoe on and walk around. Your heel should stay put, not slip up and out.
If your heel lifts out of a loafer or slip-on, the shoe has very little spare room. Try the pair in a shoe with a slightly deeper heel.
What stays the same either way
Length changes coverage, not the custom part. With both lengths, the arch shell is printed from your scan, separately for your left and right foot, and both have a deep heel cup and a cushioned heel pad. What you give up with 3/4 is the layer under the ball of your foot and your toes; what you gain is room inside a slimmer shoe.
So if you are unsure, picture the shoes you will wear most often, not the ones you wear once a month. The scan is the same, and the arch is the same, so the right length is simply the one those shoes can take. You can see the layers of each length on our How It Works page.
Can one pair work in several shoes?
Yes, if the shoes suit the same length. A full length pair moves easily between sneakers that all have removable insoles. A 3/4 pair would move between dress shoes. Full Length is available now. 3/4 Length is coming soon.
Common mistakes
- Stacking a full length insole on top of the original. It raises your foot and squeezes your toes. Take the original out.
- Choosing 3/4 for running shoes “to be safe.” If the insole comes out and there is room, full length gives cushioning under the ball of your foot too.
- Forcing a full length pair into a narrow dress shoe. If your toes feel pressed, switch to 3/4.
- Cutting too much at once. Trim a little, test, and repeat.
- Judging in a few minutes. New insoles can feel different at first. Give them a few days of shorter wear.
Still deciding whether custom is right for you? Read are custom insoles worth it? Or pick a design and order Full Length. 3/4 Length is coming soon.
Frequently asked questions
Are 3/4 length insoles as supportive as full length?
At CustomSole, both lengths have the same custom arch from your scan. The difference is coverage: 3/4 length pairs end before your toes, so there is no cushioning under the front of your foot from the insole itself.
Can I put a full length insole on top of my shoe’s insole?
It is not recommended. Two insoles stacked together raise your foot and crowd your toes. Remove the original first. 3/4 Length, for shoes whose insole is glued in, is coming soon.
Can you put insoles in any shoe?
Most shoes can take one of the two lengths. Very snug styles such as cycling shoes or some fashion sneakers may not have room for either, so check the inside of the shoe first.
Do I need to trim my insoles?
Sometimes. The toe end of a full length pair follows a standard shoe shape, so if it bunches up, trim a few millimeters at a time using the old insole as a guide.
Do 3/4 and full length cost the same?
Yes. Every CustomSole design is $69.99 a pair in either length. Full Length is available now. 3/4 Length is coming soon.
Sources
- Shoes: Finding the Right Fit, AAOS OrthoInfo
- Athletic Shoes, AAOS OrthoInfo
- Prescription Custom Orthotics and Shoe Inserts (bring the shoes you plan to wear), American Podiatric Medical Association (APMA)
CustomSole insoles are a comfort product, not a medical device. This article is general information, not medical advice. If you have ongoing foot pain, see a podiatrist.
