Median LCP product image weight on a phone
| Group | Pages | Median KB |
|---|---|---|
| Other platforms | 75 | 33.6 |
| Shopify | 123 | 35.8 |
| Ranks 1 to 3 | 35 | 32.0 |
| Ranks 4 to 10 | 71 | 41.6 |
| Ranks 11 to 20 | 93 | 32.5 |
| Beauty & health | 55 | 41.6 |
| Home, kitchen & garden | 47 | 35.8 |
Source: PageSpeed Matters, Oct 2026. Small groups; read the breakdowns as indicative.
Summary
On a product page viewed on a phone, the main product photo is often the largest thing on the first screen. That makes it the Largest Contentful Paint (LCP) element, the moment Google's loading metric measures. A heavy main image can hold back the whole page, so we wanted to know how much these images actually weigh.
The answer is: less than many store owners fear. On 199 ranking product pages loaded on a phone where the largest element was a matched image, the main product image weighed a median 35.7 KB, and 82.9% came in under 100 KB. A small tail is still heavy: 8.5% were over 200 KB.
What we measured
We loaded product pages that rank in Google for searches in commercial verticals, on a phone-sized 390x844 screen. We recorded the bytes of every image response and matched them to the image the browser reported as the LCP element.
We kept only pages where the LCP element was an image we could match to its response, which left 199 product pages. Pages whose LCP element was text or a video poster are excluded.
Two limits matter. These are phone-sized responsive images, measured by transfer size as served; desktop images on the same pages are larger. And the groups are small, so the platform, rank and vertical breakdowns are best read as indicative.
Most main product images are light
The median main product image weighed 35.7 KB. 82.9% of pages came in under 100 KB, 8.6% fell between 100 and 200 KB, and 8.5% were over 200 KB. 3.0% were over 500 KB.
The heaviest 10% of main product images start at 151 KB. That tail is where the problem pages sit: a single oversized photo on a phone connection can be the slowest part of the page to arrive.
The light median likely reflects responsive images doing their job: many store platforms and themes serve a phone a smaller file than the original upload.
82.9%
Share of 199 ranking product pages on a phone where the main (LCP) product image weighs under 100 KB.
Shopify pages keep the main image light more often
By platform, the median main image is close: 33.6 KB on other platforms (75 pages) and 35.8 KB on Shopify (123 pages).
The difference shows up in the tail. 88.6% of 123 Shopify pages keep the main image under 100 KB, against 73.3% of 75 pages on other platforms. Shopify serves product images through its own image CDN, which can resize and convert them for each screen, so many stores likely get phone-sized files without extra setup. On other platforms, image sizing depends more on the theme and plugins a store has chosen, which likely leaves more room for oversized files.
Rank and vertical make only small differences
By rank, the median main image ranges from 32.0 KB for pages ranking 1 to 3 (35 pages) to 41.6 KB for pages ranking 4 to 10 (71 pages). Pages ranking 11 to 20 sit at 32.5 KB (93 pages). There is no clear line from rank to image weight, and the groups are small.
By vertical, beauty and health product pages have a median main image of 41.6 KB (55 pages) and home, kitchen and garden pages 35.8 KB (47 pages). Both are well under 100 KB at the median.
What this means for your store
Most stores are not losing much speed to the median product photo. The risk is the outlier: a single product uploaded at full size, a theme that skips responsive sizes, or a gallery that loads the full image before the shopper taps.
- Run your best-selling product pages through PageSpeed Insights on mobile and check the LCP element and its size.
- Make sure the main image uses responsive sizes (srcset and sizes), so phones get a phone-sized file.
- Do not lazy-load the main product image. Let it load early, and consider fetchpriority="high" on it.
- Check a few products uploaded long ago or by a different team member, where oversized files are most likely to hide.
Sources
- PageSpeed Matters analysis of a phone-sized (390x844) render of ranking product pages, October 2026
- Largest Contentful Paint (LCP), web.dev: https://web.dev/articles/lcp
Embed this research
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<p style="font:14px/1.5 system-ui,sans-serif">Source: <a href="https://www.pagespeedmatters.com/resources/data-studies/product-photos-on-phones">Product Photos on Phones: 82.9% of Main Images Load Under 100 KB - PageSpeed Matters</a></p>
Frequently asked questions
How big should a product image be on mobile?
On 199 ranking product pages loaded on a phone, the main product image weighed a median 35.7 KB and 82.9% came in under 100 KB. Only 8.5% were over 200 KB, so a main image well under 100 KB puts you in line with most ranking stores.
How heavy are product images on ranking store pages?
Most are light. The median main product image on a phone weighed 35.7 KB, the heaviest 10% start at 151 KB, and 3.0% were over 500 KB.
Do Shopify product images load lighter than other platforms?
At the median they are similar: 35.8 KB on Shopify and 33.6 KB on other platforms. But 88.6% of Shopify pages kept the main image under 100 KB, against 73.3% of pages on other platforms.
Oversized product photos are one of the easiest speed problems to find and fix, and the main image is the one shoppers wait for first. Need help with this? See our ecommerce CRO agency.