The Eddington Number is a strangely addictive score for cyclists, devised by British astrophysicist Arthur Eddington for ranking their achievements in an ever-harder scale. Also known as the Eddington Scale, it is defined as "the largest integer E, where you have cycled at least E miles on at least E days (source: triathlete-europe.competitor.com). It not only gives you a nice number that you can show off to your mates, it also comes with clear progression targets for you to achieve ever-higher Eddington numbers. In other words, "how many more days riding of at least x miles do I ride to achieve that score?" Clever, eh?

It doesn't just work for cyclists; runners and swimmers can also apply the scale. The problem is that it's a little bit tricky to calculate your number, as you need to sort all your rides by distance, then bucket them up appropriately. The key to an accurate number is keeping a good record of your activities. An awful lot of people use Strava nowadays, and on that note I've produced a little tool that analyses all of your Strava rides, calculates your Eddington Number, and shows how many more rides you'll need to increase it. So, head over to "My Strava Eddington Number" page, and see what number you get!

For the record, as of October 15 2017 my number is 90 (it was 77 in December 2016, and 54 in September 2015), and I've now got to think of my net target! I need around 50 more 100-mile days, for a score of 100, so let's see how that goes.

Each tab shows the count of Eddington numbers recorded on the My Strava Eddington Number page, so we can get an idea of what are the more common ones.

- Ride
- VirtualRide
- Run
- Walk
- AlpineSki
- Swim
- Hike
- Workout
- Kayaking
- InlineSkate
- WaterSport
- StandUpPaddling
- IceSkate
- VirtualRun
- NordicSki
- RockClimbing
- Snowboard
- Snowshoe
- BackcountrySki
- Rowing
- Canoeing
- EBikeRide
- Elliptical
- Windsurf
- Kitesurf
- Surfing
- Yoga
- Crossfit
- RollerSki
- StairStepper
- Handcycle
- WeightTraining
- WinterSport

by **Emma Swanwick**
on 10 May 2020 Reply

I am looking for the actual maths used to calculate the eddington number, do you have it or know where I can get it?

by **John Swindells**
on 10 May 2020 Reply

Hello Emma, the maths is fairly simple - but it is laborious to keep track of the mileages. You need to maintain a frequency plot of each day's miles ridden - but it also needs to be cumulative. So, if you ride 54 miles in a day, then the 54-mile count increases by 1 - but so does the 53-mile count, the 52-mile count, etc. Your Eddington number is then the greatest mileage which has a count of that mileage.

by **Joe Wein**
on 02 May 2017 Reply

Perhaps if the result falls into the top 10%, you could display it with an extra decimal (assuming you have sufficient data sets for that precision to be meaningful)?

by **John Swindells**
on 03 May 2017 Reply

Interesting suggestion Joe, but I don't think there's enough data at the top end of the stats to justify that level of accuracy.

by **Joris**
on 16 October 2016 Reply

Great site, great tools! What about displaying this graph in a cumulative way, so you van easily see to which best percentage riders you belong, in terms of Eddington numbers.

by **John Swindells**
on 16 October 2016 Reply

Interesting idea, Joris! I could display it as a graph, or maybe I could just tell you what percentile you're in on your personalised Eddington Number page.

by **Reuben**
on 25 March 2019 Reply

It'd be great to be able to hover over each bar and get the distance and cumulative percent of riders at that number similar to your "Going the Distance" page. Trying to get past that 50% mark (and 50 miles, but I think those might be the same point).

by **John Swindells**
on 25 March 2019 Reply

Great idea Reuben - have a look now!

by **Vicki**
on 28 July 2015 Reply

Think this is great, thanks...

I take it rides can't be added retrospectively? I used to use Garmin to log rides before strava and tried to add my first few long training rides for comparison, but the E number didn't alter afterwards.

by **Tim**
on 24 March 2015 Reply

I'm guessing from your wording that the app uses "rides" rather than "days' mileage", so all my days that I rode to and from work as separate rides will only contribute half each? It makes more sense to do days mileage, otherwise you could log a 200 mile ride as multiple rides and boost your number...

by **John Swindells**
on 24 March 2015 Reply

I've now adjusted my Eddington Number Calculator, so that it's based on distance per day. My score went up by a measly one!

by **John Swindells**
on 24 March 2015 Reply

I agree with your logic, Tim; it certainly seems fairer to cluster rides into whole days. Indeed, I've just re-checked the definition and it is "at least E miles on at least E days".

I shall modify the calculator accordingly, so watch this space!

by **Tim**
on 01 April 2015 Reply

Marvellous work, thats much better I went up by 3 :P

All my commuting days are now below the distance required to contribute to my E, need to move further from work now...