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Bufferbloat & QoO Test

Standards-based QoO: how calls, gaming, and streaming perform under load.

Test Progress

Live during run
Baseline
DL Warmup
Download
UL Warmup
Upload
Bidirectional
Cooldown

What Each Phase Tests

Phase primer

Baseline

Your connection's inherent latency when idle (measures base network quality)

Download

How much latency increases when downloading large files (simulates streaming, software updates)

Upload

How much latency increases when uploading data (simulates video calls, cloud backups)

Bidirectional

How much latency increases during simultaneous heavy download and upload (simulates real-world mixed usage)

Cooldown

How quickly latency recovers after stopping all traffic (shows network recovery speed)

Grade Meanings

A+ to F guide
A+

Excellent

Increase: < 5 ms

Your connection has virtually no bufferbloat! Perfect for video calls, online gaming, and real-time applications. Your connection maintains low latency even under heavy load.

A

Very Good

Increase: 5–30 ms

Minimal bufferbloat with excellent performance. Great for video calls, streaming, and gaming. You may notice slight delays only during very heavy usage.

B

Good

Increase: 30–60 ms

Moderate bufferbloat that's generally acceptable. Good for most activities, though you might notice some lag during video calls or gaming when downloading large files.

C

Fair

Increase: 60–200 ms

Noticeable bufferbloat that affects performance. You'll likely experience lag during video calls, choppy streaming, and delayed responses in online games when your connection is busy.

D

Poor

Increase: 200–400 ms

Significant bufferbloat causing major performance issues. Video calls will be problematic, streaming may buffer frequently, and online gaming will be frustrating during heavy usage.

F

Very Poor

Increase: ≥ 400 ms

Severe bufferbloat making real-time applications nearly unusable. Video calls will drop frequently, streaming will buffer constantly, and online gaming will be extremely laggy when downloading or uploading.

Quality of Outcome (QoO)

Application impact

QoO (Quality of Outcome) shows how well real apps should work on your connection when the network is busy. It focuses on user experience, not just peak speed. RFC: draft-ietf-ippm-qoo.

100% QoO = improving the network more is unlikely to be noticeable for that app.

0% QoO = that app is likely to feel unusable under load.

For each app class, we compare your measured p95 latency, packet loss, and throughput to app-specific targets, then combine them with transparent weights.

Standards mapping: High = NRP (good target), Low = NRPoU (poor threshold), following IETF QoO terminology.

In each row, the marker shows your measured value versus Good/Bad ranges, and the CDF chart shows where your latency distribution sits.

Excellent
90–100%
No noticeable issues.
Good
80–89%
Meets ISP target range.
OK
60–79%
Noticeable under load.
Poor
0–59%
Likely user impact.
App class Phase Bad (minimum) Good (target) Ranges Good Bad Measured Latency CDF Good Bad

What is LibreQoS?

About the project

LibreQoS is an open-source toolkit that helps ISPs deliver low-latency, fair connections by managing queueing and bufferbloat at the edge. We offer this test so anyone can see how their connection behaves under load—and how smart QoS can keep calls, games, and streaming smooth. Learn more at libreqos.io.

What Can I Do About Bufferbloat?

Next steps

🔧 Router Solutions

Consider routers with built-in bufferbloat mitigation like Eero, Firewalla, MikroTik, or Alta Labs.

📞 Contact Your ISP

Share your test results with your Internet Service Provider. They may be able to adjust settings or upgrade equipment to reduce bufferbloat.