During C25K we concentrate on running times, but after graduation some people start talking distances, and often switch from kilometers to miles which can be confusing if your new to running. To help clarify, I thought I would just post various key target distances in ascending order so that anyone working towards a distance target can see where the next target might be.
3k, 2 miles, 5k, 8k, 5 miles, 10k, 15k, 10miles, 20km, half marathon
For those who fancy a bit of number wrangling - 1 mile is roughly 1600 metres, 1K is 1000 metres, so a 5K is (5/1.6) ~ 3.125miles.
EDIT - hmmm, am I the only who thought 'there is always one...' when reading my reply? Oh well, I guess that one is me today :-).
2 miles? 8k? 15k? 20k?
Are these common distances? I think if I was running for target distances I would push on after 15k to get in one more to make it 10 miles, and likewise if I had done 20k it would seem churlish not to squeeze out one more to tick off HM distance.
Although, to be honest, unless training for an event-specific distance, I tend to think more in terms of time on feet rather than distance these days, which I measure in 15 or 30 minute blocks. So runs can be 30 mins, 1 hr, 90, 1 hr 45, 2 hrs etc. Not that I have run for more than 2 hours for quite a while. I find not thnking in terms of set distance but total time takes the pressure off and enables me to pace myself better.
I took these distances off the predicted race performance website so assumed these are standard race distances. I know in time, converting between km and miles will become easier, but until then, this has helped me. However I usually do as you do, and run for a specific time then look to see how far I have run. I do agree that running specific times is a better performance tool.
Km/mile is a curious thing. On foot I can really only judge distance in km now, whereas in a car it is the otehr way round. I have actually tested this by driving a route I have run and as soon as i was behind the wheel of the car I automatically 'knew' how far it was in miles, whereas if you had asked me while running I would have had to convert it.
I do that too, go out for 30 mins or one hour etc - and round up my run to complete a part mile. I don't feel any pressure that way..and I would increase my time running (or time on my feet rather than distance) .
Time = endurance ( physical end mental) = strength = speed = distance ...for me anyway.
When I started to look at booking races I noticed I'd see 5k , 10k, 15k but a shorter race between 5k and 10k would be advertised as 5miles and a race between 15k and half marathon would be advertised as 10 miles; ( never in kilometres) ...just the way it is. Quite nice if you want to increase your distance by shorter increments but in the early days it did seem a bit confusing. It all makes sense eventually😊.
I'm hoping it will suddenly click one day, but so far....nope
Running familiar routes with a gps watch or phone soon enables you to become very knowledgeable as to how many Kim's or miles you've travelled, so much so you soon get to know that the oak tree on the left is your marker for 1k and the top of the hill is 4.5k ....for example.
And that's very sad and geeky because I now know how far and long, a is from b to c, to z and all other combinations for my local routes up to around 10 miles away. That's why I prefer just going out for a set time " back in an hour" ! ...Enjoy your trail runs⏱
I stick with KM although know the equivalent in miles, we are supposed to a "decimal" country aren't we
Olympic distances are km's the only 1 I can think the only one they still say in miles is the marathon isn't it?
Distances 
Why do I run?
Aim to run more 10 Km distances
Half way to my Jan target 
