How can I determine Breaking point of my Web application using JMeter?

How can I determine Breaking point of my Web application using JMeter?

How can I determine Breaking point of my Web application using JMeter? I
have executed the JMeter Testplan with different concurrent users load.
EX. 300 users(0% error), 400 users(7% error in a sample, 5% error in
another sample), 500 users(more than 10% error in 4 out of 6 samples). At
What value of % Error, I can say system reached the Breaking point.I used
concurrent users 300, 400, 500 in a PHP website. Should I consider any
other parameter to determine breaking point. How many maximum concurrent
users my application can support?