Round trip latency is the total time it takes for an audio signal to travel from your input device (microphone, instrument, game controller) through your computer’s audio system and back out through your speakers or headphones. It’s measured in milliseconds and includes every stop along the way: input device delay, driver processing, application processing, and output device delay all stacked together.
In practical terms, when you play a note on a MIDI keyboard connected to your DAW, round trip latency is how long before you hear that note back through your headphones. When you speak into a microphone in a video call, it’s how long before the person on the other end hears your voice, plus the return path. That’s why it’s called “round trip”—the signal makes a complete circuit.
How Round Trip Latency Works
Round trip latency isn’t a single delay. It’s the sum of four separate latencies happening in sequence:
Input Latency
The time between when your input device captures the signal and when your audio interface or sound card delivers it to your computer’s CPU. A high-quality audio interface typically adds 1–5 ms here. Your computer’s built-in sound card might add 10–20 ms.
Processing Latency
The time your computer takes to process the audio through your application (DAW, game engine, video call software). This depends on your buffer size. A 256-sample buffer at 48 kHz adds roughly 5 ms. A 512-sample buffer adds 10 ms. A 4096-sample buffer adds 85 ms. The relationship is simple: larger buffers = more delay, but more stability for CPU-heavy sessions.
Output Latency
The time between when the processed signal leaves your CPU and when it actually comes out of your speakers or headphones. This is typically 1–10 ms depending on your audio hardware.
Cumulative Effect
Add those three together and you get your system’s round trip latency. A well-optimized Windows music production setup might total 10–25 ms. A gaming rig might hit 15–40 ms. A video call on a laptop with built-in mic and speakers can easily reach 100+ ms if the drivers aren’t tuned.
Why Round Trip Latency Matters
The importance of round trip latency depends on what you’re doing.
For music production: If you’re recording drums with a virtual instrument or amp simulator while monitoring your input in real-time, high round trip latency creates noticeable timing lag. You’ll hear your playing delayed, which throws off your performance. Professional studios target under 10 ms. Home setups with 20–30 ms are often acceptable for recording takes, but uncomfortable for live monitoring.
For gaming: Fast-paced games (first-person shooters, fighting games, rhythm games) demand low latency. Anything above 20–30 ms total starts to feel sluggish. You press a button, and the action happens a perceptible fraction of a second later. Competitive gamers obsess over latency in the 5–15 ms range.
For live performance: If you’re triggering samples, effects, or virtual instruments on stage in sync with a click or bandmates, round trip latency under 10 ms is essential. Over 20 ms and your timing drifts noticeably.
For video calls: Round trip latency above 50 ms starts to feel like a satellite delay—people talk over each other more, interruptions happen. Most modern video call software manages this okay because the servers absorb some of the jitter, but local system latency still contributes.
For casual listening or editing: If you’re mixing, editing, or just playing back recorded audio, round trip latency doesn’t matter much because you’re not monitoring live input. A 100 ms delay doesn’t affect your workflow.
How to Measure Round Trip Latency
There are several ways to test your system’s round trip latency, depending on your setup and how precise you need to be.
Using Your Audio Interface’s Built-in Loopback
Many professional audio interfaces (Focusrite, RME, MOTU, Universal Audio) include a hardware loopback feature. Connect an output back to an input on the interface, play a click or tone through the output, measure the delay in a DAW or using a round-trip latency test tool, and the time delay you measure is your round trip latency. This method isolates the audio hardware and driver delay, excluding your computer’s CPU and application.
Using LatencyMon or Specialized Tools
On Windows, LatencyMon alternative software and similar utilities measure DPC latency (Driver Pace Counter latency), which can impact round trip latency but isn’t a direct measurement. For a more direct measurement, use the audio latency calculator to estimate based on your buffer size and sample rate, or use the DAW latency test to measure inside your recording software.
Manual Loopback Test
Record a click or beep, route it back through your interface to an input channel, and record the output. The silence between when you generated the click and when you recorded it coming back is your round trip latency in samples. Divide by your sample rate (48000 Hz for example) and multiply by 1000 to convert to milliseconds.
Perceived Monitoring Test
The unscientific but practical test: play a note on a MIDI keyboard while listening through headphones, or clap while monitoring your microphone. If it feels like there’s lag between what you do and what you hear, your round trip latency is probably above 15–20 ms.
Acceptable Round Trip Latency by Use Case
There’s no single “good” number. It depends on your workflow.
Music production with virtual instruments: Aim for under 10 ms for comfortable real-time monitoring. 10–20 ms is workable if you’re recording takes in chunks. Above 20 ms becomes distracting.
Mixing and editing: 50+ ms is fine. You’re not monitoring live input.
Gaming: Competitive play: 5–15 ms is ideal. Casual: under 30 ms is comfortable. Above 50 ms feels laggy.
Live performance: Under 10 ms is professional. 10–20 ms is acceptable. Above 20 ms risks timing issues.
Video calls: Under 50 ms is transparent. 50–100 ms is noticeable but acceptable. Above 200 ms becomes frustrating.
Live streaming: The platform (Twitch, YouTube) adds its own latency regardless of your system. Your round trip latency is less critical, but keeping your system latency under 20 ms reduces input lag for monitoring.
Reducing Round Trip Latency
If your round trip latency is too high, you have a few levers to pull:
Lower your buffer size in your DAW or audio settings. Go from 512 to 256 samples, or 256 to 128. This reduces processing latency. The tradeoff: higher CPU load and more risk of dropouts if your CPU can’t keep up.
Use ASIO drivers on Windows instead of WASAPI or Windows Audio. ASIO bypasses some system layers and typically delivers lower latency.
Upgrade your audio interface to a lower-latency model, or one with a direct monitoring feature (lets you hear your input without it going through your CPU).
Reduce CPU load by freezing/bouncing tracks, disabling unused plugins, or simplifying your session so your computer can process faster.
Update your audio drivers. Outdated drivers can add unnecessary latency.
Check your system for DPC latency spikes. High DPC latency can cause round trip latency to spike unpredictably. A separate tool like LatencyMon alternative can help diagnose this.
Frequently Asked Questions
Is 20 ms round trip latency noticeable?
Yes, for real-time activities. Anything above 15–20 ms becomes perceptible in music production, gaming, or live performance. Below 10 ms feels transparent to most people. For non-real-time work like mixing, 20 ms doesn’t matter.
How is round trip latency different from input latency?
Input latency is just the delay from your microphone or instrument to your computer. Round trip latency includes input latency plus processing delay plus output latency—the total time for a signal to come in and go back out.
Can round trip latency be zero?
No, but it can be very low (under 5 ms). Every device, driver, and software layer adds some delay. Even a direct connection to an audio interface’s loopback has a small amount of latency in the microseconds range, but that’s typically unmeasurable by human perception.
Why does my DAW show lower latency than I actually experience?
Many DAWs report only buffer latency, not total round trip latency. The full number includes input latency, output latency, and sometimes driver delay that the DAW doesn’t account for. Use a hardware loopback test for the true picture.
Dalton is an audio testing and latency optimization writer at SoundLatencyTest. He focuses on audio latency analysis, sound delay testing, recording performance, and audio troubleshooting tools for producers, gamers, streamers, musicians, and audio engineers.