Choosing sneaker sizes with cssbuy spreadsheet
The number inside your favourite pair is a habit, not a measurement. This guide shows how to turn foot length, last shape and a seller chart into a size decision you can defend, without relying on any made-up price or stock claim.
Measure your foot, not your memory
Stand on a sheet of paper against a wall, mark the longest toe, and measure heel to mark in centimetres. Do it in the evening, when feet are at their largest, and repeat for the other foot. Use the longer number. That one figure is the anchor for everything that follows.
Foot length, last shape and chart: three different things
- Foot length is your body. It does not change between brands.
- The last is the mould a shoe is built around. A narrow last and a wide last can share a size label and feel nothing alike.
- The seller chart is the manufacturer's attempt to map length to a label. It is the number to trust when it is shown.
When a listing includes an insole length or inner length in centimetres, record it. That is far more useful than a label, because you can compare it directly with your own foot plus a little room.
How much room to leave
| Use | Typical thinking | What to check |
|---|---|---|
| Walking the commute | A little room at the toe | Heel hold and forefoot width |
| Casual weekend | Comfortable, not loose | Sock thickness you actually wear |
| Five-a-side or light training | Snugger heel, free toes | Lockdown and sole flexibility |
These are starting points, not rules. If a seller states how a pair runs, treat that as one more piece of evidence rather than a verdict.
Reading brand differences honestly
Some pairs run narrow through the midfoot and some feel generous. Rather than guess, compare the inner length and the width figure if one is provided. If neither is shown, flag the row as "needs more information" in your own sheet instead of choosing a size and hoping. When you open the sneakers category, apply the same routine to every candidate so they compare on equal terms.
A five-minute shortlist test
For each candidate pair
- Write your longer foot length in centimetres.
- Find the seller chart row closest to that length, plus room for the toe.
- Record inner or insole length if it is listed.
- Note the last description: narrow, regular or wide.
- Write the intended use: commute, campus, weekend, light training.
- Mark any row missing a measurement as "ask before buying".
Where to go next
If you are weighing a dressier pair, compare designer shoes by the same method. For a full pass over photos, availability and after-sales terms, read product information to verify, and return to the cssbuy spreadsheet home page any time.