How do you judge how long your labour was?

[Fleur]

With DS I have absolutely no idea how long I was actually in labour for. I had a really long pre labour with ouchy and often fairly regular braxton hicks for about 2 weeks before hand. They would tease me and come regularly about 10 or so mins apart, and when I would get excited and hopeful this was IT! they would die down and go away.

Sounds a lot like what I had with Pie, pre-labour for 4 or 5 weeks, so when real labour started it was a few hours before I took it seriously.
My contrax started around 2am, I eventually got sick of trying to sleep & got up around 5am, was holding the kitchen bench at 7:30 while trying to make kids lunchs, lol... I called DH to come take me to my hossy appt cause I couldn't drive anyhow.
Got to hosptal & it stopped then started again, at about 1pm, had an internal & was 9cm and she wasn't born until 6:30 pm. My waters broke about 10 min before she was born, and my contractions were 5 min apart the whole time.
I count it from 1pm cause that's when it got really ouchy, but in truth you could say it was more like 13.5 hours, longer if you count from 2am

Panda, I had a hind water leak but labour started when my waters broke & contactions started straight after, 12.5 hours until she was born.

Beep - I had BH for weeks before, they were regular all day before but not painful until 6pm, but I was still able to doze through them until 2am, when I got out of bed & my waters broke. He was born at 5:30am so I count that as 3.5 hours.

I kind of count my labours from the point at which I was a) sure that I was in labour and b) ouchy enough to stop me carrying on as usual