SQM & QoS Bandwidth Calculator

Calculate safe starting download and upload traffic-shaping values to help reduce bufferbloat.

Bufferbloat troubleshooting

Find Your Router's Starting SQM Settings

Enter reliable wired download and upload results. The calculator converts a chosen percentage of those measurements into kbit/s values for routers that support SQM, CAKE, FQ-CoDel or compatible queue-management controls.

Router queue management

Calculate starting SQM limits

Run the LinkSpeed Bufferbloat Test over Ethernet with other traffic paused, then enter stable measured speeds. Start at about 90% and adjust after retesting under load. This standalone calculator is for quick download and upload shaping values in kbit/s; for testing whether SQM is needed and choosing a suitable queue-management method, follow the full bufferbloat fix guide.

Lower values may control queueing better but sacrifice more throughput. Higher values preserve speed but may leave bufferbloat.
Download shaper limit90,000 kbit/s
Upload shaper limit18,000 kbit/s

Values to enter in a compatible router

Retest Bufferbloat






Step-by-step
How to apply the figures without making things worse
  1. Measure both directions over Ethernet on an otherwise quiet connection. If speeds vary significantly, use a representative stable result rather than a single unusually fast test.
  2. Find SQM, Smart Queue Management or traffic shaping in your router. Enable CAKE or FQ-CoDel where genuinely supported. Enter the calculated limits in the units your router requires.
  3. Run the same loaded-latency or bufferbloat test again. If latency stays high, adjust gradually—try 85%, check the router processor load, and ensure QoS is actually enabled.
  4. If throughput drops sharply without improving latency, revert the settings. Some ISP routers only have priority-based QoS rather than true SQM.


Router settings and units vary. A generic QoS priority screen is not automatically the same as CAKE/FQ-CoDel. High-speed services may overwhelm a router running SQM in software. Record original settings before changing anything.


When a new router might help
Consider a router upgrade only if poor bufferbloat is repeatable over Ethernet, your current router lacks suitable queue management and you have ruled out obvious congestion and other causes.
How to Fix BufferbloatFull diagnosis and router setup guidance.Compare Home RoutersCheck specifications before buying; affiliate links may apply.
Affiliate disclosure: LinkSpeed may earn a commission from qualifying purchases via eligible buying-guide links at no extra cost to you.




SQM calculator questions
Does a bufferbloat grade of A mean I need SQM?
Generally not. If your loaded latency is already low for your use, introducing a shaper may have little benefit and may reduce throughput.
Are kbit/s and Mbps equivalent?
1 Mbps is 1,000 kbit/s for the decimal values used in typical router shaping settings. Check whether your router uses kbit/s, Mbps or another unit.
Should I use my advertised package speed?
No. Prefer reliable measured wired speeds, since effective shaping usually needs to sit below the real link capacity.