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Ecommerce · 7 min

Size-Related Returns: Find the Fit Problem Before Buying a Tool

Measure size-related returns with a consistent formula, separate physical returns from refunds, and choose an intervention for the products that need it.

Di Davide Mastricci, Founder · 16 luglio 2026

What are size-related returns?

Size-related returns are clothing items returned because they are too small, too large, or uncomfortable in a particular part of the garment. A size label can be correct while the cut still feels wrong. Keep those fit reasons separate from damaged products, delivery problems and a colour that differs from the photograph: they call for different fixes.

Start by measuring the problem in your own catalogue. A store-wide return rate cannot tell you whether to improve measurements, explain the cut, change a product or test a shopping tool.

Use one unit of measurement from start to finish

For a product group and a defined delivery cohort, use:

Fit-related unit return rate = units returned for size or fit ÷ delivered units × 100.

The numerator must refer to units in that same cohort. Do not divide returned articles by the number of orders: one order can contain several articles. If you prefer an order-based metric, count distinct delivered orders with at least one fit return and divide by all delivered orders in that cohort. Label it as an order rate, and keep it separate from the unit rate.

A second question needs a different denominator:

Share of returns due to fit = units returned for size or fit ÷ all physically returned units × 100.

The first number describes how often delivered units come back for fit. The second describes the composition of returns. Neither is a revenue-loss percentage.

Worked example: 12% and 60% can both be correct

These are invented numbers to demonstrate the calculation, not results from an aisthetix merchant:

  • 1,000 units were delivered in the chosen cohort.
  • 200 of those units were physically returned by the observation cutoff.
  • 70 were too small, 30 too large and 20 had another fit problem: 120 fit-related units in total.
  • 50 had another known reason and 30 had no recorded reason.

The fit-related unit return rate is 120 ÷ 1,000 = 12%. The share of all returned units recorded as fit-related is 120 ÷ 200 = 60%. Reason coverage is 170 ÷ 200 = 85%. Report that missing-reason share alongside the result; do not silently assign unknown returns to fit or exclude them from the all-returns denominator.

Download the blank fit-return audit CSV. It contains column headers only, with no customer data or automatic calculations. Use one row per product group and delivery cohort. Assign each returned unit one primary reason so the reason columns do not double-count it. Leave a rate undefined when its denominator is zero.

Separate physical returns from sales reversals

A refund does not always mean a garment came back. Shopify's current sales-report documentation distinguishes Reversed quantity, which can include cancellations and edits, from Returned quantity, which counts physically returned units. It also documents the line-item return reason. Use the physical-return records for this audit and reconcile the reason to the original delivered item. See Shopify's sales-report definitions.

Shopify's built-in returned-quantity rate uses ordered units as its denominator. The method above deliberately uses delivered units to exclude undelivered orders. Name that difference when comparing your worksheet with a platform report. Treat an unlinked return as an unresolved record until you can associate it with the cohort; do not invent an order match.

Give returns time to arrive

Choose a delivery period, then wait until its return window and normal processing delay have passed. Record the final observation date. Counting September returns against September deliveries mixes returns from older purchases with recent purchases that have not had time to come back.

Track the same product, size, market and measurement definitions across periods. Record missing delivery dates and return reasons. Keep exchange returns visible even if the shopper buys another size: the original item still came back, although the financial outcome differs from a refund.

Match the intervention to the evidence

  1. Repeated “too small” or “too large” reports: check the supplied garment measurements, unit labels and variant mapping. Explain whether the chart describes a body or the finished garment. Use our body versus garment measurement guide.
  2. The size is plausible but the cut feels wrong: explain stretch, length and silhouette, and add relevant product imagery. A different size may not fix a different fit preference.
  3. Several sizes of one garment in the same order: investigate possible bracketing with the two-size ordering worksheet. That order pattern alone does not prove the shopper's motive.
  4. Shoppers ask how the garment will look on them: a visual preview may address that question. Evaluate it separately from a size recommendation.
  5. Damage, fulfilment mistakes or misleading product information: fix the underlying issue. A fitting-room feature does not repair it.

Prioritize products with enough delivered units and meaningful return volume. A product with one return from two deliveries has a high percentage but little evidence. Review counts and rates together before choosing a test.

Where aisthetix fits in the decision

The aisthetix Shopify app and WooCommerce plugin provide shopper-photo virtual try-on and size guidance from the merchant's configured chart on eligible products. A generated preview illustrates appearance; it does not establish physical fit. Better-looking previews are not evidence of fewer returns.

If you test a tool, measure conversion, returned units and contribution after returns. Compare eligible shoppers assigned to the experience with a control where practical, rather than assuming people who voluntarily use it are otherwise comparable. Our try-on measurement guide separates attributed sales from incremental value.

Questions merchants ask

Is a high fit-return share proof that the size chart is wrong?

No. The reason may involve inaccurate measurements, an unclear body-versus-garment distinction, inconsistent sizing, personal fit preference or uncertainty before buying. Inspect the affected products and the shopper's reason before choosing a remedy.

What is a good size-related return rate?

There is no universal target that makes different products, markets and return policies comparable. Establish a consistently measured baseline, then test whether the same products improve without sacrificing contribution or customer experience.

Should I buy a returns app or a prevention tool first?

If return reasons and item-level records are missing, establish that measurement first. Returns management handles what happens after purchase; prevention changes what the shopper knows before buying. The returns management versus prevention guide explains the distinction.