How to Combine Two Videos Side by Side

Putting two videos next to each other sounds like a job for editing software — until you actually need it done. A reaction beside the original clip, a before-and-after, two angles of the same moment. You don't need to install anything for that. A few minutes in your browser is enough, and nothing gets uploaded anywhere.

Below is the exact flow in the free Video Collage tool. It all runs locally in your browser, so your videos never leave your device — which is also why export takes a bit of patience, more on that in Step 7.

What You Need Before You Start

Get these ready first, so you are not stopping halfway to hunt for a file:

• Two video files — MP4, MOV, or WebM. Each file must be under 300 MB; anything larger is skipped by the tool.
• A desktop or laptop computer — exporting re-encodes the whole collage in your browser, and a computer finishes much faster than a phone.
• An idea of the final shape — a wide 16:9 canvas suits YouTube, while a tall 9:16 canvas suits Shorts, TikTok, and Reels. You pick this before you start arranging.
• Music (optional) — an MP3 or similar audio file, if you want a soundtrack on top of the videos' own sound.

How to Combine Two Videos Side by Side, Step by Step

Step 1: Add your two videos

Open the Video Collage tool and drop both videos onto the dropzone, or click it to pick files from your device. Copied a video already? Ctrl+V pastes it straight in. Each video lands on the canvas as its own layer, and the moment the second one drops in, the tool lines them up side by side on its own — so by the end of this step, you are already looking at the layout this guide is building.

Step 2: Pick the canvas size

Set the canvas first, before you move anything around — it is the shape of the finished video, and changing it later means re-doing your layout. Open the Canvas menu and pick 16:9 (1280×720) for YouTube, 9:16 (720×1280) for Shorts, TikTok, and Reels, 1:1 for a square feed post, 4:5 for a portrait post, or 4:3 for a classic frame. Background color lives here too; black is the default, and it shows wherever a video does not fill its box.

↗ Canvas size is the one thing worth getting right before you place anything — open Video Collage in a new tab, set it now, then come back here.

Step 3: Choose the Side by side layout

Above the preview canvas, find the Layout row and click Side by side. Done — the two videos split the canvas evenly, left and right. And the layout buttons are only a starting point, not a lock: drag a video to move it, or drag its bottom-right corner to resize it, and the split stops being 50/50. The same row also holds Top / bottom, Grid, Picture in picture, and One fills canvas, which are covered below.

↗ If you haven't got the tool open yet, this is the moment — open Video Collage in a new tab and hit Side by side so you can watch the split happen.

Step 4: Trim each video on the timeline

Most clips need trimming before they sit well together. Click a video's chip in the Videos row to select it, then find the timeline track in its panel. Drag the two handles to set the start and end of the segment you want to keep — the trimmed part must be at least 0.5 seconds. Don't stress about getting the handles pixel-perfect on the first drag. This timeline is what-you-see-is-what-you-get: the preview shows exactly the part that will be exported, so scrub the red playhead through it, nudge the handles until it looks right, then do the same for the second video.

↗ This one is easier done than read about — open Video Collage in a new tab, pick a clip, and drag the handles while the preview plays.

Step 5: Fit the picture inside each half

Two videos rarely share the same shape, so decide per video how it fills its half. In the same panel, Fill box (crop) zooms the video until its half is completely covered, cutting off the edges; Fit whole video shows the entire frame and fills the leftover space with your background color. Faces getting cut off is the usual complaint with Fill — that's what the Crop zoom, Crop X, and Crop Y sliders are for, so you can push the framing back until the face sits where you want it. If one video should sit on top of the other, Bring forward and Send back change the layer order.

↗ Worth trying live: open Video Collage in a new tab and flip one clip between Fill and Fit — you'll see the difference in about two seconds.

Step 6: Fix the sound before you export

Sound is the step most people rush, then wonder why the export sounds off. It comes from two sources: each video's own sound, and an optional music track. In a video's panel, the Sound checkbox turns that video's audio on or off, and the Volume slider sets how loud it sits in the mix. Below that, the Soundtrack panel lets you add music files; several music files play one after another, joined into a single track, and the music loops on its own if it is shorter than the collage. Press Play and actually listen. Every sound you hear in the preview is mixed into the export exactly as you hear it — fixing the balance now is a lot cheaper than exporting twice.

↗ Seriously, don't skip the listen — open Video Collage in a new tab, press Play, and check the mix before you export.

How to Export Your Collage as One MP4

Step 7: Preview, then export

Press Play and watch the whole collage through once, checking the join between the two halves and the sound balance. Then click Export MP4. Heads-up on the first export: the tool has to load its video engine first (about 30 MB), so nothing seems to happen for a bit before the progress bar starts moving. That is normal, not a freeze — just wait it out. Once the render is running, keep this tab in the foreground with the screen on until it finishes. Exporting is heavy work for a browser; a one-minute 720p collage can take a few minutes on a computer. When it is done, click the Download link to save your collage as an MP4.

↗ Ready to finish it? Open Video Collage in a new tab, hit Export MP4, and leave that tab in front until the download link shows up.

Which Layout Should You Choose?

Side by side stays the default because it fits the most common jobs: comparisons, reactions, before-and-after — anywhere both clips deserve equal space. The rest of the row covers the exceptions:

• Top / bottom — the same idea stacked vertically, useful when both clips are tall or when the final canvas is portrait.
• Grid — the tool switches to this automatically when you add a third or fourth video; every clip gets an equal tile.
• Picture in picture — one video fills the canvas and the others sit as small windows on top, the classic layout for gameplay with a facecam.
• One fills canvas — the selected video takes the whole canvas, handy when one clip is the main story and the other is only a brief overlay you move and resize by hand.

What If the Two Videos Are Different Lengths?

Different lengths trip up almost everyone the first time, and the tool has a direct answer for it. The finished collage runs as long as the longest trimmed clip — nothing ever goes black mid-collage. For each shorter video, open its panel and set Shorter than project to either Loop, which plays the clip again from its trimmed start, or Freeze last frame, which holds the final frame until the collage ends. Or skip the setting entirely: if you would rather both clips end together, just trim the longer one down to the shorter one's length back in Step 4. One drag, done.

Common Problems and Fixes

• Clip skipped the moment you add it? Almost always the 300 MB per-file limit. Compress it first with the Video Compressor, or trim the unwanted parts out before adding it.
• One clip shows nothing in the preview? The format probably doesn't play in your browser. An MP4 encoded with H.264 is the safest choice — convert other formats first.
• Export dragging on? That's normal, not a bug: the whole collage is re-encoded in your browser. Use a computer rather than a phone, and keep clips short. A one-minute 720p collage can take a few minutes.
• Export stuck? First check the tab is still in front with the screen on — that alone fixes most stalls. If it still won't finish, try shorter clips or fewer videos.
• One side silent in the result? Either its Sound checkbox is off, or the video simply has no audio track of its own. In the second case it stays silent in the mix, and the music track (if any) still plays.
• Hitting the 3-minute cap? The tool stops exports at 3:00, no exceptions. Trim a video down and export again.
• Music ending early? It shouldn't — the joined music track loops to fill the collage, so the soundtrack never cuts out before the video does.

That's really the whole job: add both clips, pick Side by side, trim on the timeline, export. The fiddly bits — canvas shape, crop, sound balance, uneven lengths — all live on the same page, and the preview never lies about what you'll get. My suggestion: try it once with two short clips, even throwaway ones. Once the flow clicks, longer projects are just the same moves again.