I understand how you feel.
a direct way of expressing sympathy and understanding of someone's emotions or situation
used to say that you have experienced a similar situation
I understand what you mean. / I get what you mean.
used to say that you have complete understanding of a situation
a casual way of saying that you understand someone
I get what you're saying.
used to acknowledge what someone has said and express sympathy
I get it. / I get that.
said to mean that you understand a problem or issue that has been mentioned
I know how it feels.
used to express understanding of someone's situation and feelings
I've been in your shoes.
said to someone who is going through difficulty to mean that you have experienced something similar in the past
I can see why you feel that way. / I understand why you feel that way.
means that you understand how and why a person is feeling a certain type of emotion
a casual way of saying that you sympathize or empathize with someone
I can't imagine what you're going through.
said when a person is going through a very tough situation that you have never experienced, making it hard to sympathize
I know what it's like to...
said to mean you are familiar with a certain situation
a casual way of saying you understand
said to emphasize how good or bad something is, often directed towards someone who is trying to sympathize with you
Put yourself in my shoes.
used to ask someone for sympathy by asking them to imagine themselves in your current situation
used to ask someone to look at and gain understanding of a situation from your point of view
I hope you understand that...
used to explain the situation and ask for someone's understanding