ISP Speed Index

How We Calculate Rankings

Every time a customer chooses to play a title, that streamed session has a known maximum achievable bitrate. That maximum bitrate is set by the combination of the resolution requested (SD/HD/4k), streaming device, and encode recipe. The better a network is, the closer a session will be to reaching this maximum possible bitrate.

To compare the network performance of Internet Service Providers (ISPs) streaming Netflix, we do two things:

Step 1

Calculating an ISP’s performance

We divide the prime time sessions into 0.5 Megabits per second (Mbps) buckets based on the maximum possible bitrate and then calculate the time-weighted bitrate achieved for all sessions in each bucket.

This allows us to measure how close the combined sessions were to achieving their maximum bitrate level. For example, with max bitrates from 0.5-1 Mbps an ISP may achieve 0.9 Mbps (time-weighted) and for 5-5.5 Mbps the ISP may achieve 5.2 Mbps.

Sessions with Maximum Possible Bitrate (Mbps)ISP’s Time-Weighted Performance in Each Bucket (Mbps)
< 0.5
0.49
0.5 – 1.0
0.9
1.0 – 1.5
1.28
1.5 – 2.0
1.75
5.0 - 5.5
5.2

Step 2

Applying Global Normalization (simplified to the 5 buckets shown above)

We calculate the global hours distribution of these 0.5 Mbps buckets and normalize every ISP to this same distribution.

For example, if globally we see that 10% of hours occur with maximum possible bitrates between 0.5-1Mbps, then the ISP's 0.9Mbps (from the scenario above) gets a 10% weighting. Every bucket is similarly normalized to produce the Speed Index metric.

Sessions with Maximum Possible Bitrate (Mbps)Global Hours ShareISP Performance (Mbps)ISP’s Normalized Performance (Hours Share x Performance)
< 0.5
15
%
0.49
0.07
0.5 – 1.0
10
%
0.9
0.09
1.0 – 1.5
5
%
1.28
0.06
1.5 – 2.0
25
%
1.75
0.44
5.0 – 5.5
45
%
5.2
2.34
100
%
3.0 Mbps
Speed Index Metric

FAQ

How is prime time defined?

Prime time is defined as the top 3 hours of Netflix viewing each day for each ISP. So one day it might be 7pm, 8pm and 9pm for the ISP, and another day it might be 6pm, 9pm and 10pm for that same ISP.

What about cellular traffic?

The ISP Speed Index reports on home broadband networks. As such, we work to exclude direct streaming from cellular networks based on provided IP ranges/Classless Inter-Domain Routing (CIDRs) or when streaming devices log that they are connecting directly to Netflix using a cellular antenna.

Which ISPs are included?

We include broadband ISPs that consistently have >1% of Netflix view hours in the country.

Is the data sampled?

No, we use all prime time sessions.

When is data posted?

We aim to report results for the previous month on the 2nd Monday of the current month.

Where can I find historical speed index data using the original speed index methodology (2012-2020)?

This CSV file contains the historical data that was published on the index.

What are ISP types?

The types listed for an ISP are based on our understanding of the distribution networks used/advertised by the ISP. The technologies are listed in the following order: Fiber, Cable, DSL, Wireless, Satellite. Wireless refers to fixed home broadband service (e.g., WiMAX).