How to Record System Audio and Your Microphone at the Same Time

Short version: To record your computer’s sound and your voice at the same time, you either enable Stereo Mix in Windows sound settings, or use a screen recorder that captures the system loopback and your microphone together and mixes them into one file. The second option is simpler and stays in sync.

Recording just your microphone is easy. Recording just your computer’s audio is doable. The part that trips people up is capturing both at once — your narration and the video, app, or call playing on screen — in a single, in-sync recording. Here’s why it’s fiddly, and how to get it right.

Why Windows makes this harder than it should be

Windows treats output (your speakers or headphones) and input (your microphone) as two separate worlds. Most recording tools point at one of them. So when you hit record expecting both, you get your voice but silence where the system sound should be — or the other way around.

There are two ways around it.

Method 1 — Use a recorder that captures both in one pass

The cleanest approach is a screen recorder that records the system loopback and your microphone simultaneously and mixes them into a single audio track. No routing, no extra setup — you tick “system audio” and “microphone,” and both land in the file, aligned to the video.

This is exactly how KeepCast works: it captures your screen, system audio, and mic into one MP4, padding silence so the audio never drifts behind the picture. (KeepCast is a local-first Windows app — join the waitlist for early access.)

Method 2 — Enable Stereo Mix (built into Windows)

If you want to do it with what’s already on your PC, Stereo Mix exposes your computer’s output as a recordable input:

1. Right-click the speaker icon in the taskbar → Sound settings → open the classic Sound control panel.
2. On the Recording tab, right-click an empty area and enable Show Disabled Devices.
3. Right-click Stereo Mix → Enable.
4. Make sure your microphone is enabled too.
5. In your recorder, choose Stereo Mix (system) and your microphone.

Not every sound card exposes Stereo Mix, and combining two inputs cleanly can be hit-or-miss — which is why a recorder that handles both natively is the more reliable route.

Keeping the two in sync

The single biggest quality problem is drift — the audio slowly falling behind the video on longer recordings. It happens when each source is recorded on its own clock and stitched together afterward. The fix is to capture both streams together and anchor them to the video timeline, so a ten-second clip and a one-hour session stay equally tight. Pick a tool that does this for you rather than correcting it by hand later.

The quick answer

For most people on Windows: use a screen recorder that records system audio + microphone in one pass and mixes them for you. It’s fewer steps than Stereo Mix and it stays in sync — which is the whole point.