How to Add Subtitles to a Video With AI for Free

Quick answer

To add subtitles with AI for free, upload a short video, choose a caption style, generate the burned-in subtitles, and proof the entire result before downloading. Magic Hour’s public tool currently processes the first 30 seconds, accepts files up to 200 MB, supports more than 50 languages, and allows three free videos per day without sign-up.

Automatic captions are a draft. Names, numbers, specialist terms, accents, overlapping speakers and line breaks require human review. The public guest flow currently offers template selection but no word-level transcript editing.

Add subtitles to a short clip

Upload a representative clip, choose a readable template, and proof every name, number and line break before downloading.

Try Auto Subtitle Generator

Before you start: choose the output you actually need

Burned-in captions: text is part of the video and remains visible on social platforms. This is the current documented output of the Magic Hour subtitle API and the clearest use case for the public guest tool.
SRT or VTT track: a separate timed-text file can be edited, translated or turned on and off in a compatible player. Magic Hour’s public product page advertises SRT/VTT, while its current API documentation says the API returns an MP4 with embedded subtitles. Confirm the output available in your session before relying on a sidecar file.
Transcript only: use a transcription workflow when you need searchable text rather than a captioned video.

For YouTube, Google’s official caption-file guide lists the formats it can ingest. A separate caption track is usually better when viewers need to toggle captions or when you expect future corrections and translations.

How to add subtitles with Magic Hour

1. Open the free subtitle generator

Go to Magic Hour Auto Subtitle Generator. The current public flow works in the browser without an account or credit card. The page says free visitors can process three videos per day.

2. Upload one representative clip

Upload a video up to 200 MB. The public interface currently generates subtitles for the first 30 seconds, so start with a short clip that contains the names, terminology, speaker conditions and background sound found in the rest of your project.

3. Choose a readable template

The current guest interface shows Karaoke, Cinematic, Minimalist and Highlight templates. Choose based on the footage: keep text clear of faces, product details, lower-third graphics and the controls used by TikTok, Reels or Shorts.

4. Generate the captioned video

Select Generate. The tool detects speech and creates timed subtitles in the chosen visual style. Processing time varies with the clip and queue, so avoid promising a fixed turnaround.

5. Proof the entire result

Words: verify names, brands, numbers, dates and domain-specific terms against the audio.
Timing: check that each line appears with the correct speaker and disappears before the next thought.
Reading speed: split dense sentences rather than shrinking the type until it is hard to read.
Placement: preview on a phone and keep captions inside the platform safe area.
Meaningful audio: add speaker labels and relevant sound descriptions when accessibility is the goal.

The guest flow currently does not offer word-level transcript correction. If the generated wording is wrong, use a workflow that supports transcript editing rather than publishing the error.

6. Download and inspect the actual file

Download the result and watch it from beginning to end. Verify resolution, watermark, audio, caption placement and commercial-use rights for the plan you used. Magic Hour’s current pricing page says paid plans include watermark-free video exports and commercial use; free outputs are for testing and personal, non-commercial use.

A 60-second caption quality test

Prepare one reference transcript for a clip containing a proper name, number, accented phrase, pause and overlapping speech.
Generate with default settings and record the date, tool surface and template.
Count consequential errors rather than using a provider’s general accuracy percentage.
Inspect the delivery file for watermark, resolution, caption format and safe-area conflicts.
Repeat on a phone because desktop preview can hide small type and interface overlap.

Keep the source clip, reference transcript and output. This makes later tool or model changes measurable without claiming that one sample proves universal accuracy.

Common subtitle mistakes

Publishing without proofreading: a fluent transcript can still contain a wrong name or number.
Treating captions and translation as the same task: translation adds meaning and cultural review beyond speech recognition.
Putting too much text on screen: concise lines are easier to read and cover less of the video.
Ignoring the destination interface: buttons and descriptions can obscure low captions.
Assuming every advertised export is in every surface: verify browser, account and API output separately.

Frequently asked questions

Yes. Magic Hour’s current public subtitle generator offers three free videos per day without sign-up and processes the first 30 seconds of each test clip.

Not in the current simplified guest flow. Its product FAQ says word-level transcript editing is unavailable. Use an editor with transcript correction when the wording must be changed.

The public product page advertises SRT/VTT export, but the current API tool documentation says its output is an MP4 with embedded subtitles. Because those first-party pages conflict, confirm the output in the exact product or API surface you plan to use before committing to a workflow.

Magic Hour’s current product and pricing pages reserve commercial use for paid plans. Check the terms of the exact tool and plan used for any client, advertising or revenue-generating project.

Subtitles display text; they do not change the speaker’s audio or mouth movement. Use Magic Hour Lip Sync when new audio needs matching mouth movement, then create and proof captions for the final audio track.

Choose the next guide by task

Compare free subtitle tools and their actual limits when the free plan is the decision, use the broader subtitle-generator comparison for editing and delivery workflows, or compare subtitle APIs when captions must run inside a product or automated pipeline. The current Magic Hour API output is documented in the official subtitle API guide.