Borderline high is 140/80 anything higher is not good.
Doctors now want bp to be less than 120/80 and anything higher is not accepted as normal. There used to be a category of a pre-hypertension range with a measurement range higher than 120/80...that has now been discounted.
However, you need an accurate reading for blood pressure. Those cheap machines you purchase in stores are not accurate and I have seen them as far as 20 out on both diastolic and systolic pressures. You need a GP to use a cuff which they manually pump, while they listen through a stethascope.
The problem with monitoring blood pressure is that it changes all the time. You only have to quickly think of something which is bothering you and it will increase. You only have to cough and it increases. This worries people too much and they end up with high blood pressure through worrying about their blood pressure. A classic catch 22.