If you exceed the usage limits you will get an OVER_QUERY_LIMIT status code as a response. This means that the web service will stop providing normal responses and switch to returning only status code OVER_QUERY_LIMIT until more usage is allowed again. This can happen:
Within a few seconds, if the error was received because your application sent too many requests per second.
Within the next 24 hours, if the error was received because your application sent too many requests per day. The daily quotas are reset at midnight, Pacific Time.
This screencast provides a step-by-step explanation of proper request throttling and error handling, which is applicable to all web services.
Upon receiving a response with status code OVER_QUERY_LIMIT, your application should determine which usage limit has been exceeded. This can be done by pausing for 2 seconds and resending the same request. If status code is still OVER_QUERY_LIMIT, your application is sending too many requests per day. Otherwise, your application is sending too many requests per second.
Note: It is also possible to get the OVER_QUERY_LIMIT error:
- From the Google Maps Elevation API when more than 512 points per request are provided.
- From the Google Maps Distance Matrix API when more than 625 elements per request are provided.
Applications should ensure these limits are not reached before sending requests.
Documentation usage limits