The specific standards that separate accessible captions from cosmetic ones — contrast ratios, font sizes, placement rules, and background choices from WCAG and broadcast industry best practices.
Set Up Accessible Captions →A caption overlay that exists but is illegible serves no one. Tiny white text against a bright game background, decorative fonts unreadable at a glance, captions positioned over critical game UI — these are accessibility theater, not genuine accessibility. Real caption accessibility requires deliberate design choices informed by established standards from WCAG, broadcast television, and the BBC's captioning guidelines.
WCAG 2.1 SC 1.4.3 requires minimum 4.5:1 contrast for normal text and 3:1 for large text (18px+ or 14px bold). Caption text at 32px qualifies as large text but best practice is to exceed the minimum significantly.
Maximum possible contrast. Gold standard for accessibility. For burn-in overlays where occluding gameplay is acceptable, a solid dark strip with white text achieves maximum legibility.
Achieves approximately 15-18:1 contrast depending on underlying image, comfortably exceeding 4.5:1. Allows gameplay to show through. Recommended for most streaming scenarios.
Light yellow (#FFFF99) on black: approximately 14.5:1. Equally valid alternative, particularly visible in low-contrast environments.
Gray text on dark, colored text on colored backgrounds, white with drop-shadow-only on variable backgrounds — all frequently fail WCAG 1.4.3. Dark text on light backgrounds is appropriate for print but performs poorly as stream overlays.
Broadcast industry and WCAG both point to clean sans-serif fonts as the standard for caption readability. Key characteristics of accessible caption fonts:
Recommended: Inter, Roboto, Open Sans, Noto Sans, Arial. All freely available as Google Fonts.
Minimum size: 32px at 1080p. Recommended: 36-44px. At 720p: ~22-24px minimum.
Mobile consideration: Caption text readable on a 1080p monitor may be difficult on a 5-inch phone screen. Err larger to serve mobile viewers.
rgba(0,0,0,0.75) — the standard recommendation. High contrast, gameplay visible through caption area. Looks professional and is the approach used by most professional streaming setups.
Full black bar across the lower third. Maximum 21:1 contrast, no gameplay visibility through caption area. Best for compliance-critical or accessibility-priority broadcasts.
White text with dark drop shadow, no background box. Visually light but contrast varies dramatically with underlying image — can drop below WCAG minimum in bright game environments. Do not use for accessibility-targeted captions.
StreamTranslate at streamtranslate.live/setup provides caption delivery with sub-500ms latency. Activate the Twitch Extension at streamtranslate.live/twitch for viewer-controlled captions alongside your OBS overlay.
WCAG 2.1 SC 1.4.3 requires minimum 4.5:1 contrast for normal text, 3:1 for large text (18px+). White on black achieves 21:1; white on rgba(0,0,0,0.75) comfortably exceeds 4.5:1.
Minimum 32px at 1080p. Many broadcasters use 36-44px. At 720p scale to approximately 22-24px minimum.
Clean sans-serif fonts: Inter, Roboto, Open Sans, and Arial. Avoid thin weights, decorative fonts, or all-caps, which reduce legibility at a glance.
Lower third standard: 60-80px above the absolute bottom edge, spanning full width. Avoid overlapping health bars, minimaps, or critical game UI.
Semi-transparent dark background: rgba(0,0,0,0.75) is recommended — high contrast for white text while keeping gameplay visible. Fully opaque strip achieves maximum contrast but occludes gameplay.