Climate friendly speed tests

TL;DR

Speed test loads a lot of data to measure your download speed. Due to the widespread use of speed tests, they contribute significantly to global CO2 emissions. It is therefore preferable not to use a speed test if it is not really necessary. Should you use a speed test? Then use Internet Speed at a Glance or use Google Fiber.

These speed tests take the least time (and therefore data) to measure the download speed. As a result, they have the smallest ecological footprint (0.30 and 16 grams of CO2 respectively).

The rule of thumb for determining the carbon footprint of a speed test is:
The carbon footprint in grams of CO2 is twice the download time in seconds.

Content

  1. Why the carbon footprint of a website matters
  2. How to get the carbon footprint of a speed test
  3. The carbon footprint per speed test
  4. The median carbon footprint of a speed test
 

Why the carbon footprint of a website matters

Web pages and tools that you use on the Internet cost electricity and therefore have a carbon footprint. According to the IPCC, reducing CO2 emissions is critical for your future.

One of the most popular tools on the Internet are speed tests. Speed tests are that popular that when you Google for "speed test", Google gives you the option to start a Measurement Lab (M-Lab) speed test directly.

Because a speed test loads extra data to measure your download speed, a speed test has a huge impact on the worldwide CO2 emission. Millions of tons are involved every day.

 

How to get the carbon footprint of a speed test

To get the carbon footprint of a speed test two things are required:

  1. An unambiguous relationship between the size of a download (in Mb) and the carbon footprint
  2. A good estimate of the amount of data (in Mb) that is loaded during a speed test

The relation between download size and carbon footprint

Sites as Website Carbon Calculator indicates the CO2 required for a webpage. By testing multiple webpages it is possible to relate the CO2 required to the size of the webpage.

The carbon print of a webpage

The carbon footprint of the home pages of the tested speed tests, as measured with the Website Carbon Calculator, are the following (less is better):

  1. LibreSpeed 0.03 gram CO2
  2. Fast 0.04 gram CO2
  3. Google Fiber 0.15 gram CO2
  4. Bredbandskollen 0.21 gram CO2
  5. Comparitech 0.22 gram CO2
  6. Measurement Lab (M-Lab) 0.23 gram CO2
  7. Broadband Internet Speed test 0.24 gram CO2
  8. Meter.net 0.27 gram CO2
  9. Internet Speed at a Glance 0.30 gram CO2
  10. Xfinity Speed Test 0.31 gram CO2
  11. nPerf 0.44 gram CO2
  12. SpeedSmart 0.44 gram CO2
  13. Open Speed Test 0.50 gram CO2
  14. Fireprobe 0.51 gram CO2
  15. SamKnows Speed Test 0.66 gram CO2
  16. Which Broadband Checker 0.70 gram CO2
  17. Testmy.net 0.71 gram CO2
  18. Bandwidth Place 0.78 gram CO2
  19. Broadband Speed Checker 0.82 gram CO2
  20. DSLReports 0.82 gram CO2
  21. SpeedOf.me 1.01 gram CO2
  22. Toast 1.23 gram CO2
  23. Speedtest4.php 1.71 gram CO2
  24. Cloudflare 1.78 gram CO2
  25. Ookla Speedtest 1.86 gram CO2
  26. RCN 2.15 gram CO2
  27. CompareSpeedTest 3.56 gram CO2

According to the Website Carbon Calculator the average web page tested produces 1.76 grams CO2 per page view. Only 4 of the tested speed tests are worse than average.

The relation between download size and carbon footprint

Based on the above carbon footprints and the size of the homepages as measured with the Pingdom Website Speed Test the following is concluded:

  1. LibreSpeed: 0.03 gram CO2, 36.4 kb
  2. Fast: 0.04 gram CO2, 498.2 Mb
  3. Google Fiber: 0.15 gram CO2, 477.4 kb
  4. Bredbandskollen: 0.21 gram CO2, 421.0 kb
  5. Comparitech: 0.22 gram CO2, 422.8 kb
  6. Measurement Lab (M-Lab): 0.23 gram CO2, 430.8 kb
  7. Broadband Internet Speed test: 0.24 gram CO2, 467.1 kb
  8. Meter.net: 0.27 gram CO2, 1.3 Mb
  9. Internet Speed at a Glance: 0.30 gram CO2, 558.2 kb
  10. Xfinity Speed Test: 0.31 gram CO2, 545.7 kb
  11. nPerf: 0.44 gram CO2, 966.5 kb
  12. SpeedSmart: 0.44 gram CO2, 816.2 kb
  13. Open Speed Test: 0.50 gram CO2, 959.9 kb
  14. Fireprobe: 0.51 gram CO2, 837.9 Kb
  15. SamKnows Speed Test: 0.66 gram CO2, 1.1 Mb
  16. Which Broadband Checker: 0.70 gram CO2, 1.4 Mb
  17. Testmy.net: 0.71 gram CO2, 1.6 Mb
  18. Bandwidth Place: 0.78 gram CO2, 1.3 Mb
  19. Broadband Speed Checker: 0.82 gram CO2, 2.7 Mb
  20. DSLReports: 0.82 gram CO2, 1.1 Mb
  21. SpeedOf.me: 1.01 gram CO2, 1.3 Mb
  22. Toast: 1.23 gram CO2, 2.2 Mb
  23. Speedtest4.php: 1.71 gram CO2, 3.6 Mb
  24. Cloudflare: 1.78 gram CO2, 973.6 Mb
  25. Ookla Speedtest: 1.86 gram CO2, 2.9 Mb
  26. RCN: 2.15 gram CO2, 3.6 Mb
  27. CompareSpeedTest: 3.56 gram CO2, 6.7 Mb

The relation between the size of the homepages and the carbon footprint in one graph Based on the results above the formule for a trendline is:
Carbon Footprint (in gram CO2) = 0.53 * size in Mb - 0.02

 

The estimated amount of data (in Mb) required for a speed test

For a speed test the following formula applies:
Megabits downloaded = Download speed in Mbps * download time in seconds

With a download speed of 84 Mbps (the real download speed provided by the ISP used), it is clear that every second that a speed test is downloading data, to calculate the internet speed, 84 Mbits are downloaded.

1 byte = 8 bits, hence you might state that every second 84 / 8 = 10.5 Megabyte is downloaded.

Hence the formula:

Carbon Footprint (in gram CO2) = 0.53 * size in Mb - 0.02

might be rewritten as:

Carbon Footprint = 0.53 * 84 * time for downloadtest in seconds / 8 - 0.02

 

The carbon footprint per speed test

The following list gives the estimated carbon footprint per download test.

  1. Internet Speed at a Glance: 0.30 gram CO2 (the homepage is the speed test)
  2. Google Fiber: 8 seconds ≈ 45 gram CO2
  3. CompareSpeedTest: 25 seconds for the complete test ≈ roughly 9 seconds for the download test ≈ 50 gram CO2
  4. LibreSpeed: 10 seconds ≈ 56 gram CO2
  5. Measurement Lab (M-Lab): 10 seconds ≈ 56 gram CO2
  6. Toast: 10 seconds ≈ 56 gram CO2
  7. Bredbandskollen: 22 seconds for the complete test ≈ roughly 11 seconds for the download test ≈ 61 gram CO2
  8. Meter.net: 24 seconds for the complete test ≈ roughly 11 seconds for the download test ≈ 61 gram CO2
  9. Testmy.net: 25 seconds for the complete test ≈ roughly 11 seconds for the download test ≈ 61 gram CO2
  10. Broadband Speed Checker: 36 seconds for the complete test ≈ roughly 13 seconds for the download test ≈ 72 gram CO2
  11. Open Speed Test: 35 seconds for the complete test ≈ roughly 14 seconds for the download test ≈ 78 gram CO2
  12. nPerf: 70 seconds for the complete test ≈ roughly 15 seconds for the download test ≈ 84 gram CO2
  13. Bandwidth Place: 15 seconds ≈ 84 gram CO2
  14. Which Broadband Checker: 36 seconds for the complete test ≈ roughly 15 seconds for the download test ≈ 84 gram CO2
  15. SpeedSmart: 16 seconds ≈ 89 gram CO2
  16. Fireprobe: 18 seconds ≈ 100 gram CO2
  17. Comparitech: 21 seconds ≈ 117 gram CO2
  18. Ookla Speedtest: 21 seconds ≈ 117 gram CO2
  19. Xfinity Speed Test: 22 seconds ≈ 123 gram CO2
  20. Fast: 23 seconds ≈ 128 gram CO2
  21. DSLReports: 24 seconds ≈ 134 gram CO2
  22. SpeedOf.me: 25 seconds ≈ 139 gram CO2
  23. Cloudflare: 56 seconds for the complete test ≈ roughly 27 seconds for the download test ≈ 150 gram CO2
  24. RCN: 27 seconds ≈ 150 gram CO2
  25. SamKnows Speed Test: 28 seconds ≈ 156 gram CO2
  26. Broadband Internet Speed test: No meaningful results
  27. Speedtest4.php: No meaningful results
 

The median carbon footprint of a speed test

To know the median carbon footprint of a speed test we first need to know the median download speed.

According to Ookla the global median download speed for mobile in March 2022 is 29.60 Mbps. So it is probably better to estimate the carbon footprint based on 30 Mbps in stead of 84 Mbps.

This results in the following formula: Carbon Footprint = 0.53 * 30 * time for downloadtest in seconds / 8 - 0.02 = 1.99 * time for downloadtest in seconds - 0.02

1.99 is almost 2 and 0.02 is that small compared to 2 that it is safe to state the following rule of thumb:

Rule of thumb

The rule of thumb for calculating the medium carbon footprint in 2022 is:

The carbon footprint in gram CO2 is twice the download time in seconds.

Based on the rule of thumb mentioned these are the global median carbon footprints:

  1. Internet Speed at a Glance: 0.30 gram CO2 (the homepage is the speed test)
  2. Google Fiber: 8 seconds ≈ 16 gram CO2
  3. CompareSpeedTest: 9 seconds ≈ 18 gram CO2
  4. LibreSpeed: 10 seconds ≈ 20 gram CO2
  5. Measurement Lab (M-Lab): 10 seconds ≈ 20 gram CO2
  6. Toast: 10 seconds ≈ 20 gram CO2
  7. Bredbandskollen: 11 seconds ≈ 22 gram CO2
  8. Meter.net: 11 seconds ≈ 22 gram CO2
  9. Testmy.net: 11 seconds ≈ 22 gram CO2
  10. Broadband Speed Checker: 13 seconds ≈ 26 gram CO2
  11. Open Speed Test: 14 seconds ≈ 28 gram CO2
  12. nPerf: 15 seconds ≈ 30 gram CO2
  13. Bandwidth Place: 15 seconds ≈ 30 gram CO2
  14. Which Broadband Checker: 15 seconds ≈ 30 gram CO2
  15. SpeedSmart: 16 seconds ≈ 32 gram CO2
  16. Fireprobe: 18 seconds ≈ 36 gram CO2
  17. Comparitech: 21 seconds ≈ 42 gram CO2
  18. Ookla Speedtest: 21 seconds ≈ 42 gram CO2
  19. Xfinity Speed Test: 22 seconds ≈ 44 gram CO2
  20. Fast: 23 seconds ≈ 46 gram CO2
  21. DSLReports: 24 seconds ≈ 48 gram CO2
  22. SpeedOf.me: 25 seconds ≈ 50 gram CO2
  23. Cloudflare: 27 seconds ≈ 54 gram CO2
  24. RCN: 27 seconds ≈ 54 gram CO2
  25. SamKnows Speed Test: 28 seconds ≈ 56 gram CO2
The median carbon footprint

The median carbon footprint of a speed test is 30 gram CO2.

With 0.30 gram CO2 Internet Speed at a Glance has clearly the least carbon footprint (a factor of 100 less than the median speed test).