How to Split a Long Image (Does a 10,000px Product Page Load Faster in Pieces? Seams, Size and Load Time)

I split an 860×10,000px product page into 3 to 16 pieces and compared file size, seams and phone load time, plus where to cut.

When uploading a product page or a long screenshot, you'll often hear "if it's too long, split it." But does splitting make it load faster? Will the seams show, or the files grow? Using PicLever's Image splitter, I cut an 860×10,000px product page into 3 to 16 pieces and compared file size, seams and phone load time.

Bottom line: the number of pieces barely changed the total size, and when the pieces were put back together no seams were visible. But splitting didn't make the page load faster. On a slow connection, the first screen of a single JPG appeared in 1.6 seconds; with 4 pieces it took 3.6 seconds. What changed the speed was the output format, not the piece count. Saving as the default PNG turned a 1.3MB JPG into 5.1MB and stretched the full load to 27 seconds, while WebP (857KB) was the fastest.

File size by piece count and format

Total file size by format and phone load time for an 860×10,000px product page split into 4 pieces

Output format	3 pieces	4 pieces	8 pieces	16 pieces
Original (one JPG)	1.3MB	1.3MB	1.3MB	1.3MB
PNG (default)	5.1MB	5.1MB	5.1MB	5.1MB
JPG	1.2MB	1.2MB	1.2MB	1.2MB
WebP	839KB	857KB	861KB	856KB

Piece count hardly affected size. From 3 to 16 pieces, totals varied by under 0.4% for JPG and 3% for WebP.
The default output format is PNG. Splitting a JPG original as-is made it 4× heavier, so for photo-heavy pages switch the output format to JPG or WebP.
Saving as JPG compresses once more, but the result stayed above 42 dB PSNR against the original, indistinguishable to the eye.

Do pieces load faster?

Upload	First screen complete	Everything loaded
One JPG	1.6 s	7.2 s
4 JPG pieces	3.6 s	7.0 s
16 JPG pieces	2.6 s	7.0 s
4 WebP pieces	2.6 s	4.9 s
4 PNG pieces	12.7 s	27.2 s

A single JPG is drawn top-down as it arrives, so its first screen was the fastest. With pieces, the browser downloads several at once and splits the bandwidth, so the first piece finished later.
Even with lazy loading for the lower pieces, the first screen of 4 JPG pieces took 2.4 seconds, still slower than one image.
The full load time was similar regardless of piece count, and only switching to WebP cut it from 7.0 to 4.9 seconds.

Where to cut: equal grid vs custom cuts

Cut positions on an 860×10,000px product page: equal grid with 4 rows, custom cuts at section edges, and custom cuts with the vertical line left in

Method	Piece size	Where it cut
Equal grid, 4 rows	2,500px × 4	Mid-photo
Custom cuts (section edges)	2,242 · 1,818 · 2,042 · 3,898px	Gaps between sections
Custom cuts with defaults left on	430px wide × 8	Also cut down the middle

Put back together, every method matched the original. PNG pieces were pixel-identical, and with JPG and WebP the areas near seams were no more degraded than anywhere else.
An equal grid ignores sections. Of the 29 lines of text in this sample, 8 pieces cut through 1 line and 16 pieces through 2. If you'll later update just one section, custom cuts in the gaps between sections are easier to manage.
When you first switch to Custom cuts, there's a vertical cut (at the image center) as well as a horizontal one. Leave it in and you get 8 pieces only 430px wide, so click the vertical cut's × to remove it.

When splitting makes sense

4,096px per-side limit: PicLever saves each piece at up to 4,096px per side. A 10,000px image couldn't be saved in 1 or 2 pieces; the default was 4 rows.
Upload size limits: split when a store or board limits the size of each image. For Naver Smart Store, see Smart Store Detail Page Image Specs.
Sections you update often: keep changing parts like prices or shipping info in their own piece, and replace only that piece.
If load speed is the goal: saving as WebP or reducing file size helped far more than splitting.

Test setup

Sample: an 860×10,000px product page made from 4 product photos and 29 lines of text (JPG quality 92, 1.3MB)
In PicLever Image splitter, split with an equal grid of 3, 4, 5, 8 and 16 rows and custom cuts (2,242 · 4,060 · 6,102px), saved as PNG, JPG and WebP, then measured file size, PSNR of the re-joined image against the original (8px above and below each seam measured separately) and how many text lines a cut crossed · Tested 2026-10-19
Loading: a web page stacking the pieces was opened 3 times in Chrome at phone width (390px), throttled to 1.6 Mbps with 150 ms latency; medians reported. "First screen" is when the visible area matched its final look. Real stores vary with their image servers and apps.

Splitting a long image with PicLever

In the Image splitter, click Choose image and add your image (up to 20MB and 30,000px tall).
For equal pieces, choose Equal grid, set Rows and leave Columns at 1.
To cut by section, choose Custom cuts, remove the vertical cut with ×, then use + Add for horizontal cuts and enter their positions (px).
Change the Output format to JPG or WebP, click Generate pieces, then Download all as ZIP.

FAQ

Q. Is my image uploaded to a server?
No. Splitting runs on your device.

Q. How are files named?
Each piece gets row and column numbers, like originalname_r01_c01. Sorting by name gives the upload order.

Q. Can I split several images the same way?
In Batch edit, you can apply the same rows and columns to up to 20 images, with cut positions set as percentages.