How Much Storage Does a Podcast Really Need?

Podcast hosting plans talk about storage and downloads, and both numbers can look confusing when you are starting out. The good news is that the math is simple. A few minutes with a calculator tells you what you need.

How big is one episode?

An audio file's size comes from two things: how long it is and how many bits of audio it holds each second, which is called the bitrate. The formula is bitrate times length.

• 128 kbps stereo MP3 is about 57.6 MB for each hour.
• 96 kbps MP3 is about 43.2 MB for each hour.
• 64 kbps mono MP3 is about 28.8 MB for each hour.

Speech does not need a high bitrate. A mono recording at 64 to 96 kbps sounds clean for talk shows and interviews. Music shows and shows with a lot of sound design benefit from 128 kbps stereo.

Storage: what you keep

Storage is the total size of all your audio files, plus your artwork, which is tiny by comparison. Here is a quick example.

• A weekly 45 minute show at 128 kbps makes files of about 43 MB.
• Over 52 weeks, that is about 2.2 GB for the year.
• After five years, about 11 GB.

A daily show at the same quality adds about 15.7 GB a year. Video podcasts are much larger, often several gigabytes for one hour, so video shows need much more storage.

Downloads: what your listeners take

Downloads are the number of times your files are fetched by listeners and apps, and the amount of data that moves is the file size times the number of downloads.

• 1,000 downloads of a 43 MB episode moves about 43 GB.
• 10,000 downloads of the same episode moves about 430 GB.

Many plans count downloads rather than data, with an allowance each month. A new episode gets most of its downloads in the first week, and older episodes keep getting a trickle. A new show with a small audience can sit comfortably in a small allowance for a long time.

Two numbers, two limits

Storage and downloads are separate. A show with a huge back catalog and a small audience uses a lot of storage and few downloads. A short new show with a large audience is the opposite. When you compare plans, check both numbers against your own show.

How to keep files smaller

1. Record in mono if your show is one voice or a conversation recorded on one microphone.
2. Export at 64 to 96 kbps for speech.
3. Cut the dead air and false starts. This helps your listeners as much as your storage.
4. Do not upload video if you only need audio.
5. Do not keep re-uploading. Replace an episode's file only when it really needs fixing.

What if you go over?

Check what your host does. Some stop accepting uploads, some charge by the gigabyte, and some ask you to move to a bigger plan. At OnlyCasts, you can see your storage and download usage for the current month in your account, and you choose whether to allow charges for going over. Nothing is billed without your say.

A rule of thumb

For most spoken word shows, a few gigabytes of storage and a few thousand downloads a month is plenty to start. Pick a plan that gives you room to grow for a year, and revisit it when your numbers show you are close.