How do I tell time in Lucid dreams?

I see people saying 'Oh this was a 3 minute dream, oh this was a 10 min dream " How do people do that?

Personally whenever I've said that, it's only been an estimate, unless I checked the time right before falling asleep, then again after waking up. But generally my estimates tend to be fairly accurate, since the perception of time in dreams is the same as when awake. The only time when I can accurately measure it is if I'm wearing my REM Dreamer. It flashes every 2 minutes, so I could count if I wanted.

yeah, estimate. But ive had dreams (non LD) that felt like for days. Maybe it all has to do with vividness because those dreams were extremely vivid

Thanks :-)

Yea, usually I am just estimating on how much time it felt like it had passed. I have no idea if dream time and regular time pass at the same rate (and people will argue this, and I still don't buy any of the evidence for either argument). Sometimes I know how much RL time passed because I looked at a clock right before and right after the dream, but even then who knows. So usually, it's just an estimate on how long the dream seemed to last, in dream minutes that are equated to RL minutes.

I guess by how long I think it might have been.