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I was trying to understand the Heroku pricing system. Okay so the free account receives 1000 dyno/hour. What's the exact meaning of a dyno/hour? It depends on what? Requests per seconds? Number of users? If i want to switch to the non sleeping offer, i'll have to pay 7$ per dyno. So the 1000 free dynos will cost me 7000$ per month? How many users approximately does 1000 dyno/month support? Thanks.

Marc Ibrahim
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1 Answers1

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Assuming you verify your account with a credit card, you have 1000 free dyno hours per month to play with.

A "dyno hour" is simply one hour of a dyno running.

If you have just 1 app running just 1 dyno, that dyno could be available 24/7 forever, since even a 31 day month consists of 31 x 24 = 744 hours, which is less than the 1000 free dyno hours you have at your disposal.

However, if your one dyno on your one app is a "web dyno" (i.e. a web server), then note that free web dynos sleep after 30 minutes of inactivity (in which case the next request to the web dyno "wakes it up").

Free web-dyno sleeping is a two-edged sword. On the one hand, when a web dyno sleeps, it does not consume any of your free dyno-hours (so you might be able to get more for your 1000 free dyno hours, depending on your needs). If you can tolerate slow response to your web clients in response to any queries that happen to wake up a sleeping dyno - that can be OK. If not, you will need to make sure to keep your web dyno busy (i.e. make sure it does not go 30 minutes without receiving any requests).

For further details see Free Dyno Hours.

Note that a dyno is basically just a virtual machine. It is your "server". One dyno can certainly support many many users, depending on the complexity / performance requirements of your app. You can "scale" your app both "vertically" (meaning increased computing capabilities per dyno) and "horizontally" (meaning running multiple dyno instances that load balance your app's traffic). See What is a Heroku "Dyno"?. Your app would need to be processing absolutely GIGANTIC amounts of traffic to justify scaling a dyno to 1000 instances. If you really need to scale your dynos (highly unlikely if you're only just starting to build your app), you will need to use paid dynos.

Yoni Rabinovitch
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    Thanks for your answer. However, the 744 hours per month that the one dyno is providing me is 744 hours of what? Of the time that the request takes to come from the server to my app? I am currently testing my app and i have found that this month i have used around 200 dynos. Is that possible? Or because i have a slow internet connexion? – Marc Ibrahim Oct 31 '16 at 07:05
  • You have definitely not used 200 dynos!!! You may have used 200 dyno hours, for example if you have had 1 dyno "awake" for 200 hours this month. So, the 1000 "free" hours you get is 1000 hours of dyno run time. That means, if you have 1 free dyno in your app, whenever it is awake, it is consuming hours from your free allocation. – Yoni Rabinovitch Oct 31 '16 at 07:14
  • Yeah that's right so i have used 200 hours of the one free dyno available. How many free dynos do i have? And the 7$, if pay them, are for an additional dyno? Or an additional dyno/hour for the one dyno i'm using? – Marc Ibrahim Oct 31 '16 at 07:32
  • And if i buy an additional dyno, i get 744 more hours of usage during this month? Thanks – Marc Ibrahim Oct 31 '16 at 07:38
  • If you move to paid dynos (e.g. $7 / month "hobby" dynos), they never sleep. For $7 you get a "hobby" dyno for 1 full month. – Yoni Rabinovitch Oct 31 '16 at 07:59
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    where can i see my dyno usage in the admin? – Omar Nov 15 '17 at 23:45
  • Hop over to https://dashboard.heroku.com/account/billing. There you can see a "Free Dyno Usage" category that shows you how many free dyno hours you have consumed this month, and how many you have remaining. – Yoni Rabinovitch Nov 16 '17 at 06:58