Free tool · no account
Aspect ratio calculator
Exact letterbox bars, visible area and export sizes for any target ratio. It gives you the padding answer and the cropping answer together, because they are different numbers and mixing them up costs you the top of the frame.
Letterbox — bars top and bottom
- 3840 × 1607
- Visible area
- 277
- Bar height
- 25.6%
- Frame lost
- 3840 × 1607
- Crop instead
px, no crop
px per side
to bars
keep full width
To reach 2.39:1 by resizing rather than adding bars, export at 3840 × 1607 (keeping the full width) or 5162 × 2160 (keeping the full height). The first crops top and bottom; the second crops the sides.
Bars or crop: two different questions
“Make this 2.39:1” has two valid answers, and they produce different files. Padding keeps every pixel you shot and adds black to fill a fixed delivery size — the frame stays 3840×2160 and the image sits in the middle. Cropping changes the delivery size itself: the file becomes 3840×1607 and the discarded area is gone.
Which you want depends on where the file is going. A timeline with a fixed resolution, or a platform that expects 16:9, needs padding. A still going to print, or a master you will re-frame later, wants the crop. The calculator reports both so the choice is explicit rather than accidental.
What each ratio is for
Frequently asked questions
What size are 2.39:1 letterbox bars on a 4K timeline?
On a 3840×2160 frame, 2.39:1 leaves a visible area of 3840×1607, so each bar is 277px tall — 553px of the frame lost in total, about 25.6%. On a 1920×1080 timeline the same ratio gives 1920×803 with 139px bars.
What is the difference between 2.35:1 and 2.39:1?
2.35:1 was the anamorphic standard before 1970; 2.39:1 replaced it and is what 'scope' means today. They are close enough that people treat them as interchangeable, but on a 3840px-wide frame the visible height differs by 27 pixels. If you are matching existing footage, use the ratio that footage was actually finished at.
Should I add bars or crop?
Adding bars keeps every pixel of your image and pads the frame, which is what you want when delivering to a fixed timeline size. Cropping changes the export dimensions and permanently discards image outside the new ratio. This calculator gives both answers because conflating them is the usual reason an export comes back with heads cut off.
Why does letterboxing lose so much of a 4:3 frame?
Because the ratios are far apart. Fitting 2.39:1 inside a 4:3 frame keeps only the middle 56% of the height. The wider the gap between source and target, the more the bars eat — which is the argument for shooting open gate and choosing the delivery ratio later, rather than committing in camera.
What ratio should I use for Instagram?
4:5 is the tallest the feed displays without cropping, so it occupies the most screen. 1:1 is safe but wastes vertical space, and 9:16 is for Reels and Stories rather than the feed. Portrait 4:5 at 1080×1350 is the practical default.
Is anything uploaded?
No. This tool is pure arithmetic and runs entirely in your browser. It never touches a file, so there is nothing to upload in the first place.