About this tool
Merging images combines two or more pictures into a single output - side-by-side, stacked vertically, or in a grid layout. Common uses are before-and-after comparisons, multi-photo social posts, simple collages, and step-by-step recipe / tutorial images.
The tool runs in your browser. You drop multiple images, pick the layout (horizontal / vertical / 2x2 grid), and the result is rendered onto a single canvas. Images are auto-scaled to a common dimension so they tile cleanly. Output is PNG by default to preserve any transparency in the inputs.
How it works
Add 2 or more images
Drop multiple files at once or pick them in sequence. The tool keeps the order you added them.
Pick a layout
Horizontal (side-by-side), Vertical (stacked), or 2x2 grid (4 images).
Adjust spacing
Set the gap between images and an optional border color.
Download
The merged canvas saves as a PNG. Re-order or remove inputs to re-merge differently.
Use cases
Before-and-after comparisons
Renovations, fitness progress, photo edits - place the two images side-by-side at the same scale for a credible comparison.
Social media multi-photo posts
A 2x2 grid for Instagram, a horizontal pair for Twitter, three stacked images for a Pinterest "tutorial pin".
Recipe and DIY step-by-step
Show 3-6 stages of a process in one image. Easier to share than a multi-page document.
Real estate listings
Combine front, kitchen, and master bedroom into a single hero image for a thumbnail.
Format and spec details
| Layouts | Horizontal, Vertical, 2x2 Grid |
|---|---|
| Max images | Limited only by browser memory - tested up to 9 images in a 3x3 |
| Output format | PNG (preserves transparency) |
| Auto-scaling | All inputs are scaled to match a common dimension to tile evenly |
Tips and best practices
- Resize all inputs to a common aspect ratio first for the cleanest output.
- Use a small gap (4-8 px) and a white border for a polished look.
- For Instagram, use a square output (1:1). 1080x1080 fits the feed without auto-cropping.
- Save the merged file as PNG to keep transparency; convert to JPG if you need a smaller file later.
How to use the Merge Images
The Merge Images is a browser-based tool that runs entirely on your device. Inputs you enter never reach a server - all calculations happen client-side in JavaScript. This means:
- Privacy: nothing is logged, sent, or stored by 3Tej. Inputs disappear when you close the tab.
- Speed: results update as you type. No network round trip.
- Offline use: once the page is cached, it works without internet.
- No signup: no account, no email, no rate limits.
Step by step
- Enter your inputs in the form above. Each field is labeled with its unit (currency, percent, kg, etc.) and the expected range.
- Read the result as it updates. The number reflects the formula commonly accepted in Merge Images-related calculations.
- Adjust to see sensitivity: change one input at a time and watch how the output moves. This is the fastest way to understand which variable matters most.
- Copy or screenshot the result for later reference. The page state persists for the session if your browser allows it.
When you would use this
- Quick estimates: when you need a number now and don't want to open a spreadsheet.
- Sensitivity analysis: testing how a result changes as inputs vary, before committing to a real-world decision.
- Comparison: running the same calculation with different inputs to compare options side by side.
- Learning: building intuition for how the underlying math behaves.
- Documentation: capturing a snapshot of inputs and outputs at a point in time.
Privacy and offline operation
Every operation in this tool runs client-side using your browser's built-in APIs (Canvas, Web Audio, WebAssembly). No data is uploaded. After the initial page load you can disconnect from the internet and the tool keeps working.
We use Google Analytics and AdSense for the page itself, but neither sees the content of the files you process.
Frequently asked questions
Can I add a label or caption to each image?
This tool does not add text overlays. Use Image Watermark afterward to add captions.
What happens if my images are different aspect ratios?
They are scaled and padded so they tile evenly. The shortest dimension wins for horizontal merges; the narrowest for vertical.
Can I merge a portrait and a landscape photo together?
Yes - they will be scaled to a common height (horizontal merge) or width (vertical). Aspect distortion is avoided by adding padding rather than stretching.
How many images can I merge?
No hard limit. 2-9 is typical; 16+ may slow your browser if the source images are very large.
Is the Merge Images accurate?
The Merge Images applies the standard formula for merge images. Accuracy is limited only by your input precision. For decisions with material consequences, use the result as a starting point and verify with a qualified professional or the relevant official source.
Is the Merge Images free?
Yes. 100% free, no signup, no payment, no API key. The site is funded by display ads that appear around the tool but not inside the calculation flow.
Are my inputs saved?
No. Inputs stay in your browser tab. Closing the tab discards them. The site uses Google Analytics for traffic measurement (anonymized) but does not see what you type into the form.
Can I use the Merge Images on my phone?
Yes. The tool is responsive and tested on iOS Safari, Android Chrome, and major desktop browsers. Touch targets meet Apple's 44pt and Google's 48dp minimum guidance.
How do I report a bug or suggest improvement to the Merge Images?
Email hi@3tej.com with the URL of this page and a description of what you saw vs expected. We typically respond within 72 hours and update calculators when rules or formulas change.
How accurate is the Merge Images?
It applies the standard formula. Accuracy is limited only by your input precision. For decisions with material consequences (taxes, medical, legal, structural), use the result as a starting point and verify with a qualified professional in the relevant field.
Is the Merge Images free to use?
Yes. 100% free, no signup, no payment, no API key. The site is funded by display ads around the tool but not inside the calculation flow.
Are my inputs saved anywhere?
No. All inputs stay in your browser tab. Closing the tab discards them. The site uses Google Analytics for traffic measurement (anonymized) but the analytics never see what you type into the form.
Does the Merge Images work offline?
Yes. Once the page has loaded, it works without internet. The calculation runs in JavaScript on your device.
Can I share results from the Merge Images?
Take a screenshot or copy the output. The page doesn't generate shareable URLs for specific calculations - inputs stay in your browser only.
Why are the results different from another merge images tool?
Most likely: different formula assumptions, different default values, different rounding rules, or different applicable rates. Check the methodology if both tools document it. Both can be valid for different scenarios.