What is a b-roll coverage ratio?

The coverage ratio is the percentage of your finished video that will show b-roll footage instead of the talking head or main subject. A ratio of 70% means 70% of the final video plays b-roll over voiceover or interview audio.

What average clip length should I use?

Most documentary and corporate videos use 3–8 second b-roll clips. Shorter clips (2–4 s) feel more energetic; longer clips (6–10 s) feel more cinematic. If you are unsure, 5 seconds is a safe default.

Why add a safety buffer?

Not every clip you shoot will make the cut — some will be out of focus, too short, or redundant. A 20–30% buffer ensures you have enough usable footage. Experienced shooters often add 25% for run-and-gun work and 15% for controlled environments.

Does this account for multiple camera angles?

The result gives you the total unique b-roll seconds needed. If you plan to offer multiple angles of the same subject, multiply the clip count by the number of angles you want per scene.

Can I use this for social media short-form videos?

Yes. Enter the full duration of your reel or short (e.g., 0 min 60 sec) and set a high coverage ratio (80–100%) if you plan to run continuous b-roll with audio overlay throughout.

B-Roll Duration Planner

Name: B-Roll Duration Planner
Availability: InStock
Author: Nham Vu

Enter your interview or voiceover duration, coverage ratio, and average clip length to get the exact number of b-roll clips and total shoot time you need.

Project Settings

Interview / Voiceover Duration

Minutes

Seconds

B-Roll Coverage Ratio: 70%

10% (minimal) 100% (full)

Average Clip Length (seconds)

Typical range: 3–8 seconds per clip.

Safety Buffer: 25%

0% (no buffer) 100%

Results

Fill in the settings and click Calculate.

Summary

Enter your interview or voiceover duration, coverage ratio, and average clip length to get the exact number of b-roll clips and total shoot time you need.

How it works

Enter the total duration of your interview or voiceover in minutes and seconds.
Set the b-roll coverage ratio — the percentage of your final video that will use b-roll over the talking head.
Enter the average length of each individual b-roll clip in seconds.
Add a safety buffer percentage to account for unusable or duplicate shots.
Read the results: total b-roll seconds needed, number of clips to shoot, and estimated shoot time.

Use cases

Pre-production planning for documentary or interview-style videos.
Calculating a shot list length before a b-roll filming day.
Budgeting shoot time when hiring a videographer by the hour.
Estimating how many location setups fit into a single shoot day.
Teaching video production students about coverage ratios.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu