Subtitle background box
A box behind the caption replaces whatever the footage is doing with one calm colour. It is the most reliable readability effect there is, and the most visible one. Compare it below on the scene where outlines struggle most.
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Busy footage, with and without a box
Stripes of light and dark run straight through the left-hand caption, and even its outline has to fight them. On the right, a box behind the whole line with 24 × 12 px padding gives the words a background of their own.
Background settings in the editor
| Setting | Editor range | Start with | Why |
|---|---|---|---|
| Background | Off · Behind line · Behind word | Behind line | One box per line reads as a single unit. Word boxes look more designed but break the line into pieces. |
| Fill colour | Any solid colour | Black | The box only has to contrast with the text. A brand colour works if the text on it still passes a contrast check. |
| Padding across | 0–60 px | 16–24 px | Enough room that letters do not touch the box's sides. Behind word draws half this padding, so word boxes can sit close together. |
| Padding down | 0–60 px | 8–12 px | Keep it about half the padding across. More makes a tall box that covers more of the frame than the text needs. |
| Corner radius | 0–60 px | 8–16 px | Square corners read as broadcast subtitles, round ones as social captions. It is a style choice, not a readability one. |
Use it when
The background is busy or unpredictable
Crowds, signage, patterned clothing and fast cuts all compete with text. A box removes the competition entirely.
Text has to read at any size
Thin or small type that an outline would choke stays clear on a box, so a box is the safer choice for lighter fonts.
You want a recognisable caption style
A coloured box with rounded corners is a strong visual signature for a series, and the shape does not depend on the footage.
Skip it when
The caption sits over something that matters
A box hides what is behind it. Over faces, product shots or on-screen text, move the caption first; the [safe areas guide](/guides/subtitle-safe-areas) shows how.
Lines are long
A wide two-line box covers a large share of a vertical frame. Shorten lines or lower the words per line before reaching for a bigger box.
Every word has its own box and the words move
Word boxes that pop in one at a time make the line jump around. Pair them with a calm entrance, or use a line box instead.
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Line boxes and word boxes
Behind line draws one box around each line of the caption. Behind word draws a separate box around each word with half the padding, so the gaps between words stay visible. Line boxes are easier to read; word boxes suit punchy, short captions.
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A box and an outline together
With a solid box behind the text, an outline adds little. Many caption styles turn the outline off once the box is on, which keeps letter shapes cleaner. Keep it if the box colour is close to the text colour.
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Highlight boxes on the spoken word
The Pill emphasis draws a filled shape behind the word being spoken and uses the same background colour, padding and radius. That is a word-timing effect; see word-by-word captions for how it plays.
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Translucent boxes
A box the picture shows through keeps more of the shot visible, but its contrast changes with the footage under it. Test the worst frame, not the average one, with the subtitle contrast checker.
Questions about this effect
Is a background box better than an outline?+
For readability, usually yes: a box guarantees the colour behind the letters. An outline covers less of the picture. Choose the box when the footage is busy and the outline when the shot matters.
What is the difference between Behind line and Behind word?+
Behind line draws one box per line of text. Behind word draws a smaller box around each word, using half the padding.
Can the box be see-through?+
The editor's colour picker sets a solid colour. Some preset styles carry their own box colours; check any translucent box against the brightest part of your footage.
Will the box appear in an SRT or VTT file?+
No. The box is drawn into the video when you export an MP4. Subtitle files carry text and timing, and each player styles them its own way.