Podcast Episode Length Optimiser

How it works

Two things are computed. The recommended window intersects a format range with your listening context: the low end is the larger of the format minimum and 0.7 × the audience minimum, the high end the smaller of the format maximum and 1.2 × the audience maximum. File size then uses the midpoint of that window, as (bitrate ÷ 8) × minutes × 60 ÷ 1024 megabytes, so 128 kbps for an hour is about 56 MB. The table repeats that size math for five durations.

Topic / format moves the answer most: Interview, the default, targets 35–65 minutes where Daily news / brief targets 5–12. Audience type then clips that window, with Commute (20–40 min), Workout (30–45 min) or Deep listen (60–120 min). Ad load changes nothing about the recommendation; it only subtracts 1.5, 3 or 6 minutes for Light, Medium and Heavy to show content time. Encoding bitrate touches file size alone, and 64 kbps AAC speech halves the megabytes of the 128 kbps default.

The ranges are baked-in editorial rules of thumb, not measurements of your own retention data, and nothing about your show's depth or pacing is modelled. Size assumes constant bitrate, so VBR encodes, artwork and chapter tags shift the real file by a few percent. Pick a mismatched pair, Daily news / brief with Deep listen for instance, and the two clamps cross, so the window prints backwards as 42–12 min. Read that as a contradiction rather than a recommendation.

Frequently asked questions

Format sets the length more than the content does

The format presets encode real audience conventions: news briefings run short, interviews long, educational content in the middle, and commute-oriented shows target a journey rather than a topic. Those are listener expectations rather than production rules, and a show that violates its format's convention has to earn the departure.

The commute framing is the most literal: a show built for a 30-minute journey that runs 50 minutes gets abandoned partway regardless of quality.

Consistency, and the ratio nobody budgets for

Consistency of length matters more than the length itself. Listeners slot a show into a habit, and one that swings between 20 and 90 minutes is harder to fit into a routine than one that is reliably either.

For production planning, the ratio worth knowing is that recorded time is a fraction of total time. Scripting, research, editing and publishing routinely take several hours per finished hour, and interview shows add scheduling and guest coordination on top.

Speaking rate converts script to runtime at roughly 130–150 words per minute for conversational delivery — slower than most people estimate, and slower still for material that needs to be understood rather than merely heard.