More than numbers. In keeping with theme of treating patients, not just numbers, we don't have a typical cutoff at which we make a diagnosis of hypertensive emergency. Rather we look for associated (potential) evidence of end-organ damage. Someone who walks into an office for regular check up w/o complaint might be managed as outpt whereas someone complaining of headache, etc might have more aggressive treatment.
Urgency vs emergency. Pre-hypertension generally goes above 120 systolic, 80 diastolic. Recent guidelines gave 140/90 and higher BP readings as hypertension. But the numbers are a range in people who don't have short-term serious illnesses. Over time the constantly high BP damages your blood vessels. Complications from this include : heart attack, stroke, kidney failure, loss of eyesight...These are emergent, goto ED.