Online vs in-store sales by category: finding the channel skew
The short answer
Divide each category's online share of sales by the business's overall online share, and multiply by 100, to compare online vs in-store sales by category. An index above 100 means the category over-indexes online, and below 100 means it leans to stores. The biggest gaps show where range, stock and marketing should differ by channel.
Ecommerce vs store sales mix, by category
Why it matters
Treating every category the same way across channels leaves stock and marketing in the wrong place. A channel index shows which categories customers prefer to buy online and which in store, so ranges, inventory and campaigns can follow.
The question to ask
Copy this into Lexi as written.
How to work it out
1. Calculate shares. For each category, divide online sales by total sales for the year.
2. Index against the total. Divide each category's online share by the overall online share and multiply by 100.
3. Check the customers. For high-skew categories, see whether the same customers buy them online and other categories in store.
What the answer looks like
Illustrative output on sample data
Illustrative example: how Lexi answers this for a home improvement retailer that sells 25% online overall. It indexes each category's online share against that average.
- Smart home devices: 55% online, index 220
- Lighting: 32% online, index 128
- Lumber and building materials: 6% online, index 24
What the data shows
Smart home devices skew heavily online, while lumber is almost all bought in store.
What it means
Many smart home buyers also buy paint and tools in store, so the skew reflects how the category is shopped.
What to do
Hold deeper online stock for smart home devices and keep display models in stores.
Want me to show which customers buy across both channels?
Frequently asked questions
What is a channel index?
A channel index compares a category's share of sales in one channel with the business's overall share in that channel. An index of 100 matches the average, above 100 over-indexes and below 100 under-indexes. It makes categories of different sizes comparable at a glance.
Why can channel mix by category be misleading?
Stock and range differ between channels. If a category has a wider range online, or regularly sells out in stores, its online share reflects availability as much as customer preference. Check range and stock levels by channel before moving inventory on the index alone.
Should online orders collected in store count as online?
Count them as online sales, since the purchase decision happened online, but track click and collect separately. For categories with a high click and collect share, stores still matter for the handover, which affects how you staff and stock them.