Bloomberg API request limit

there is an upper limit on Bloomberg API, 500,000 hits per day. -- information from Bloomberg Help Help

from Bloomberg HelpDesk on April 2014 (this is valid for a basic desktop client):

We have 3 kind of limits..

You can have no more that 3500 real time fields open at the same time. If you exceed this limit you will see "NA Limit" as error message and you just need to delete some securities/ fields in order for the error message to disappeared and to see the values.

We have also a daily limit. The Daily API limit is 500,000 hits/per day. A "hit" is defined as one request for a single security/field pairing. Therefore, if you request static data for 5 fields and 10 securities, that will translate into a total of 50 hits. so try to refresh just the portion of the spreadsheet that really needs to be refreshed and avoid refreshing it all or reopen it many times a day.

The last limit is a monthly limit. Our monthly limits comes from a proprietary model. Only about 0.4% of our user database ever goes over this limit. This limit is based on unique securities and depends on the type of data being downloaded. For example some of the data on the system such as intra-day is valued a little bit higher than historical end of day for any given list of securities. We do not recommend more than 5000 to 7000 unique identifiers per month and the limit upgrade will only allow you to get data to complete your project. Once a security is used once in a month then if you use it again it will not count again towards the monthly limit.

We normally grant 2 resets per month in case you exceed your daily limit and if you exceed your monthly limit we grant 1 extension per month (10% more), if you breach the limit again you will then need to wait for the midnight for the daily limit to be reset automatically or the end of the month for the reset of the monthly.

Bloomberg do not state what the explicit limits are, and there is no programmatic way of finding out what the limits are or what proportion of your limits you have used.

The best information from Bloomberg that I have found is on the WAPI page (in the terminal). On the menus on the LHS, go to WAPI Home > API Resources > API Data Limits. There are two pages, 'Extended Rules and Usage Limits' and 'Managing Your API Data Limits' that shed some further light on the matter.

Broadly speaking... there is a daily limit of individual data requests (i.e. security/field pairs - but duplicates are counted for each request). However, your limit for subscriptions is based on the number of securities you are subscribing to concurrently - i.e. if you expect to be requesting the price of a security every 5 mins, you are much better off subscribing to that security's price. Then there is a monthly limit that is based on the number of unique securities that you are making requests for.