And it rarely stops at two. A brief might also include a 4:5 Instagram feed post, a square version, or for some uses a cinema format such as Flat or Scope. Keeping all of these in check in one Blender scene is harder than it sounds. In this post we explain how we approach it, and introduce the free add-on we built to make it easier.
One Master Render or Several Renders?
There are two ways to deliver the same animation in several aspect ratios. You can set up and render each format separately, or you can render one larger master frame and crop every format out of it.Separate renders still make sense for some animations. If the composition has to change a lot between formats, for example when a wide camera move simply doesn't work in a narrow frame, or when the product needs to sit in a different place in each version, it is better to treat each format as its own shot.
In many cases, though, a single master render cropped to the final formats is the better way to go:
- You render once, which matters a lot when an animation takes hours or days on the farm.
- Every version shows the same frames, lighting and timing, so they stay consistent with each other.
- Late changes only need to be rendered once, not once per format.
- Cropping and reframing happens in editing, where it is quick to adjust. We cover that stage in our guide to editing 3D animation videos.
The master frame costs some extra pixels compared to a single format, but usually far fewer than separate renders. A Full HD 16:9 frame and a 1080×1920 vertical frame together need about 4.1 million pixels per frame when rendered separately. One 1920×1920 master that holds both needs about 3.7 million.
The Manual Way: Calculating Resolutions and Guides
Doing this by hand in Blender takes two steps. First you calculate the render resolution: the smallest frame that contains every format you need. For 16:9 landscape plus 9:16 vertical that is easy, a 1:1 square. Add a 4:5 post, a cinema format or a 4K version next to Full HD, and the maths quickly gets awkward, especially once you start scaling the resolution up or down.Then you need to see each format while you frame the shot, otherwise you are guessing what a 9:16 crop of your 16:9 shot will cut off. For a long time we used Blender's camera safe areas with custom values for this. It works, but it is fiddly to set up, the values need recalculating every time the resolution changes, and in practice it only covers about two formats at once.
Blender Auto Format: A Free Add-on for Multi-Format Renders
That is why we built Blender Auto Format, and we are giving it away for free. It does both steps for you:- A database of popular formats. It comes with 26 delivery formats grouped into Video, Cinema (DCI), Social: Vertical and Social: Feed. The sizes are taken from each platform's or standard's own documentation, from YouTube and ITU-R to ISDCF, Meta, TikTok, Pinterest, X and LinkedIn.
- Automatic resolution. Tick the formats you deliver, press Set Resolution, and the render resolution becomes the smallest size that holds every ticked format at full size, centred. Full HD 16:9 plus an Instagram Reel gives 1920×1920.
- Labelled camera guides. Set Guides draws a coloured frame for each format in camera view, labelled with its name, resolution and aspect ratio, so you can see exactly which part of the frame ends up in each version.
- As many formats as you need. The guides are not limited to two formats like safe areas are. Tick as many as the project requires.
In the clip above, we tick Full HD 16:9, Instagram Reel and Pinterest Pin 2:3. The panel previews the result, a 1920×1920 render with each format as a native 1:1 crop. Set Resolution applies it, and Set Guides draws a labelled frame for each format in camera view. It is immediately clear that the sphere and the cube will be cut off at the edges of the Reel, while the monkey head stays in every format.
Configurable Guides and Custom Formats
The guides are only viewport overlays, so nothing from them ends up in the final render. You can change their opacity and line width, and shade the area of the frame that no format uses, which shows at a glance where you are spending render time on pixels nobody will see. Formats that share a size, such as Reels, TikTok and Shorts, share one guide to keep the view clean.If a client needs a size that isn't in the list, such as an LED wall or an unusual billboard, you can add a custom format with a name, width and height. It then works like any built-in format. Custom formats, ticked formats and guide settings are saved with the .blend file.
Scaling: Pixel-Exact or Downscaled Crops
When formats of different sizes share one frame, you have to decide how large each crop may be. Auto Format gives you three options:- Native 1:1 keeps every format at its exact delivery size. A 1080×1920 Reel is a 1080×1920 crop of the master, so no scaling is needed in editing. This gives the smallest master resolution and the shortest render time.
- Integer Downscale lets a crop grow to 2×, 3× and so on, where it fits. With 4K 16:9 and Full HD, both use the whole 4K frame, and the Full HD version is an exact half-size downscale.
- Any Downscale makes every crop as large as the frame allows. Next to 4K 16:9, a Reel becomes a 1215×2160 crop instead of 1080×1920 and is scaled down to the delivery size in editing.
In short: choose Native 1:1 when render time matters most, and the downscale options when you want each format to use as much of the master frame as possible. Downscaling also tends to give slightly cleaner, sharper results than a native-size crop.
Get Blender Auto Format for Free
Auto Format lives in one panel under Properties › Output, works in Blender 4.2 LTS or newer on Windows, macOS and Linux, and every change it makes can be undone with Ctrl Z. You can download it for free from our Gumroad store.If you need an animation delivered in several formats but would rather not set it up yourself, that is what we do. Take a look at our animation work, including a medical product animation made for an Instagram Reel, and get in touch or book a 30-minute call.
