Check the crowd before you leave home. Search any airport above, or pick one below.
Searching for any other airport adds it here.
Every flight fills the terminal before it leaves — passengers arrive one to three hours ahead, and they arrive together. We take the published departure schedule, work out how many people that puts in the hall at each moment, and compare it to how that airport usually is.
So this is an estimate, not a measurement. We don't have cameras or sensors in the queues, and nobody else does either at most airports. What we can tell you is whether right now is busier or quieter than usual — which is normally the thing you actually want to know.