What Is Bufferbloat and Why It Ruins Your Zoom Calls

You pay for 300 Mbps internet. Your speed test says everything looks great. But the moment someone in your house starts a large download or fires up a 4K stream, your Zoom call turns into a slideshow. Your voice cuts out. Your video freezes. The other participants stare at a pixelated ghost of your face. The problem is not your internet speed. The problem is bufferbloat.

Bufferbloat is one of the most common and least understood causes of internet lag. It affects millions of households worldwide, and the worst part is that traditional speed tests will never detect it. In this guide, we will explain exactly what bufferbloat is, why it specifically destroys real-time applications like Zoom, and how you can test for it and fix it.

What Is Bufferbloat? A Simple Explanation

Bufferbloat is excessive latency caused by oversized buffers in your network equipment. To understand it, think of your router like a post office. When you send data packets across the internet, your router queues them up and sends them out one by one. The buffer is the waiting room where packets sit before being transmitted.

In a well-configured network, this buffer is small. Packets arrive, wait a tiny fraction of a second, and get sent on their way. Your idle latency might be around 15-20 milliseconds, and under load it stays roughly the same.

But most consumer routers ship with massively oversized buffers. Manufacturers do this intentionally because larger buffers prevent packet loss during traffic spikes. The trade-off, however, is devastating: when the buffer fills up during heavy usage, new packets must wait behind hundreds or thousands of queued packets. Your latency spikes from 15ms to 200, 400, or even 800 milliseconds. That delay is bufferbloat.

Why Bufferbloat Specifically Destroys Zoom Calls

Not all internet activities are affected equally by bufferbloat. Downloading a file? You will not notice it at all. Loading a web page? Maybe a slight delay. But real-time, bidirectional communication like video conferencing is uniquely vulnerable to bufferbloat, and here is why.

Zoom, Google Meet, Microsoft Teams, and other video conferencing platforms send and receive tiny data packets every 20-30 milliseconds. These packets carry fragments of your voice and video. The system is designed to work with low, consistent latency. When bufferbloat adds 200-800ms of delay, several things break simultaneously:

• Audio cuts out or echoes: Voice packets arrive too late to be useful, so the app drops them. You hear choppy audio or silence.
• Video freezes: Video frames arrive out of order or too late. Zoom shows the last good frame while it waits, creating the infamous frozen face.
• Lip sync breaks: Audio and video packets experience different delays, causing your lips to move out of sync with your voice.
• Connection quality drops: Zoom detects the latency and aggressively downgrades your video quality, switching from HD to a blurry thumbnail.
• Screen sharing lags: Your colleagues see your screen updates seconds after you make them, making collaboration painful.

The core issue is that Zoom requires one-way latency under 150ms to function well. The ITU-T G.114 standard recommends a maximum of 150ms one-way delay for acceptable voice quality. Bufferbloat regularly pushes latency to 200-800ms, which is 2-5 times beyond the acceptable threshold. At that point, the call experience degrades from professional to unusable.

Why Traditional Speed Tests Miss Bufferbloat Entirely

Here is the frustrating part: if you run a standard speed test after your Zoom call drops, it will probably say your internet is fine. Traditional speed tests measure throughput (how many megabits per second you can download and upload) and maybe a basic ping measurement. But they measure ping when your connection is idle, not when it is under load.

Bufferbloat, by definition, only appears under load. When data is flowing through those oversized buffers at capacity, latency spikes. A standard speed test does not measure latency during the download and upload phases. It measures speed, reports your idle ping, and calls it a day. Your ISP sees 300 Mbps down, 20 Mbps up, 15ms ping and tells you everything is working perfectly.

This is exactly why pong.com measures latency under load as a core part of every test. We saturate your connection with traffic (just like a real-world scenario where multiple devices are active) and simultaneously measure how much your latency increases. The difference between your idle latency and your loaded latency is your bufferbloat measurement, and we grade it from A to F so you instantly know where you stand.

Bufferbloat Grades: What A Through F Means

When you run a connection health test on pong.com, you receive a bufferbloat grade based on how much your latency increases when your connection is under maximum load. Here is what each grade means and how it translates to real-world experience:

Most households with standard ISP-provided routers score a D or F on the bufferbloat test. This is not because their internet connection is bad. It is because their router's buffer management is bad. The good news is that bufferbloat is fixable, often without upgrading your internet plan or buying expensive equipment.

Real-World Impact: Gaming, Streaming, and Video Calls

Gaming with Bufferbloat

Competitive gaming demands consistent, low latency. A player on a connection with 20ms idle ping and Grade F bufferbloat might see their in-game ping jump from 20ms to 300ms+ the moment a family member starts a download or streams video. In fast-paced games like Valorant, Call of Duty, or Fortnite, this causes rubber-banding (teleporting back to previous positions), delayed hit registration, and missed shots that should have landed. Many gamers blame their ISP or game servers when the real culprit is their router's buffer management.

Video Streaming with Bufferbloat

Streaming platforms like Netflix and YouTube are less affected because they use large playback buffers. They download video ahead of time so momentary latency spikes do not cause buffering. However, if bufferbloat is severe enough, even streaming quality can degrade as the adaptive bitrate algorithm detects congestion and drops to lower resolutions. You might notice 4K content suddenly switching to 720p or lower when multiple devices are active.

Video Calls with Bufferbloat

As discussed above, video calls are the most impacted. Unlike streaming, video conferencing is bidirectional and real-time with no playback buffer. Every packet of audio and video must arrive within a tight window (under 150ms one-way) or it gets discarded. Zoom, Teams, and Google Meet all suffer equally. If you have ever wondered why your Zoom calls work fine in the morning but fall apart in the evening, bufferbloat during peak household usage is almost certainly the answer.

How Pong.com Detects Bufferbloat

Unlike traditional speed tests that only measure throughput, pong.com runs a comprehensive connection health analysis that specifically targets bufferbloat. Here is how the test works:

1. Baseline latency measurement: We first measure your idle ping by sending small packets to our edge servers across the real public internet. This establishes your baseline latency.
2. Saturate the connection: We then flood your connection with download and upload traffic, simulating a heavy real-world load like multiple streams, downloads, and uploads running simultaneously.
3. Latency under load measurement: While your connection is saturated, we continuously measure your latency. This is the critical step that traditional speed tests skip entirely.
4. Calculate the delta: The difference between your idle latency and your loaded latency is your bufferbloat measurement. A small difference means minimal bufferbloat. A large difference means severe bufferbloat.
5. Assign a grade: Based on the latency increase, we assign a letter grade from A (no bufferbloat, 0-5ms increase) to F (severe bufferbloat, 200ms+ increase).

Crucially, pong.com tests through the real public internet, not inside your ISP's walled garden. This means the bufferbloat measurement reflects what actually happens when you use Zoom, play Fortnite, or stream Netflix. The test path goes through the same routers, peering points, and internet exchanges that your real traffic does.

The Fix: Smart Queue Management (SQM)

The single most effective fix for bufferbloat is enabling Smart Queue Management (SQM) on your router. SQM uses intelligent algorithms like fq_codel or CAKE to manage your router's packet queue. Instead of blindly stuffing packets into a massive buffer, SQM keeps the queue short, prioritizes latency-sensitive traffic, and drops packets strategically to prevent the buffer from bloating.

The results of enabling SQM are typically dramatic. A connection that scored an F on the bufferbloat test (350ms+ latency under load) will often improve to an A (under 25ms latency under load) immediately after enabling SQM. Your idle latency stays the same, and your maximum throughput may decrease by 5-10% as the overhead of queue management, but the real-world experience improvement is transformative. Zoom calls stay clear during downloads, gaming stays responsive, and web pages load instantly even when your connection is busy.

For a detailed step-by-step guide on enabling SQM and other bufferbloat fixes, read our companion article on how to fix bufferbloat on your router.

Frequently Asked Questions About Bufferbloat