# One size filter above the fold: +2% revenue per visitor

- Outcome: Won
- Page type: Collection page (Ecommerce)
- Elements: Filters, sorting & site search
- Test run by: [Optimizely](https://liftarchive.com/practitioners/optimizely/)
- Commentary by: LiftArchive (our analysis, not theirs)
- Original source: https://www.optimizely.com/field-notes/articles/experimentation-use-cases-retail-product-page
- Page: https://liftarchive.com/test/optimizely-footwear-consolidated-size-filter/

Merging men's and women's shoe size filters into one option and moving it above the fold raised revenue per visitor by 2%. Optimizely ran the test for a footwear retailer and published it as an Optimizely Field Notes use case. The vendor puts the value at about $12.7M in incremental revenue.

## Result

**+2% revenue per visitor**

- Revenue per visitor: +2%. This is the headline number.
- Size filter use: +33.8%, which shows shoppers wanted to filter by size.
- Incremental revenue: about $12.7M, as estimated by Optimizely. The source page does not say what time period this covers.
- Sample size, test length and confidence level were not shared.

## Control

Men's and women's sizes sat in separate filters, placed where shoppers were less likely to see them.

## Variant

Both size ranges were combined into a single size filter shown above the fold.

## Why it likely won (our reading)

- Shoppers often care first about whether a shoe comes in their size, so a visible size filter matches how they shop.
- Filtering early saves shoppers from opening a product only to find their size is out of stock.
- One combined filter is simpler than two, especially for unisex styles or shoppers buying for someone else.

## Caveats

Anonymized vendor summary with no sample size, duration or confidence level. The $12.7M figure is the vendor's own estimate, and its time period is not stated.

## How to run this test

- Hypothesis: If we merge size filters into one option and show it above the fold, then revenue per visitor will rise because shoppers only see products available in their size.
- Primary metric: Revenue per visitor
- Guardrail: Size filter usage
- Guardrail: Zero-result filter rate
- Guardrail: Product page exits after size selection
- Who should test it: Footwear and apparel stores where size availability varies a lot by product. Less useful for one-size products or small catalogs where shoppers can scan everything anyway.

---

Credit: Optimizely ran this test and owns the result. Summary and commentary by LiftArchive (https://liftarchive.com/test/optimizely-footwear-consolidated-size-filter/).
Usage: Free to use, quote and build on, with credit and a link: name the practitioner or organization that ran the test and link to its LiftArchive page. The results belong to the practitioners who ran and shared them; the summaries and commentary are LiftArchive's.