Several types of fields in Marketo have requirements for the type of data that can be stored, as well as the limit to how much data can be contained in that field type. The Custom Field Type Glossary can tell you what fields are available, and this article will show you details on the type and maximum limits for those fields.
Field Types & Limits
Can only be set to “true” or “false” (stored in the database as 1 or 0).
Maximum value of 9223370000000000000. Will be displayed with the currency set in your instance under Admin -> Location.
Must be formatted “MM/DD/YYYY”.
Must be formatted “MM/DD/YYYY HH:MM:SS”.
Must be a properly formatted email (firstname.lastname@example.org).
Can include decimals up to the hundredths place. The value will round to the nearest hundredth (eg. 99.999 rounds to 100, 99.985 rounds to 99.99). Maximum value of 10000000000.
See this guide: Create and Use a Concatenated String (Formula) Field
Values are limited to between -2147483647 to 2147483647.
Must be a full number without decimals. Maximum value of 9223370000000000000.
Can have letters, numbers, or characters. Maximum of 2,000 characters.
Maximum score of 9223372036854775807. If the score is increased higher than that, the score will reset to -9223372036854775808.
Can contain letters, numbers and special characters. Limit of 255 total characters
Can contain letters, numbers and special characters. Limit of 65,535 bytes.
"http://" will automatically be appended to the value if the value doesn't have that prefix or "https://" already. Does not have to be formatted any further (Generic top-level domain not required).