Reference

Indiana API county codes

Every Indiana API well number starts with 13, the state code. The next three digits are the county code, one of the 92 listed below, so a number beginning 13-001 belongs to a well in Adams County.

To decode a whole number, including the sidetrack and completion digits, paste it into the API well number decoder.

How to read a Indiana API number

13State: Indiana
001County: Adams
12345Well, unique within the county

The first ten digits identify one well. Two more digits can follow for a sidetrack, and two after that for a later completion. The county is the one where the well starts at the surface, so a horizontal well that crosses a county line keeps its surface county's code. A few state regulators assign the producing county instead, so the state record is the final word on a well near a boundary.

All 92 Indiana counties

County code County API numbers start
001 Adams 13-001-
003 Allen 13-003-
005 Bartholomew 13-005-
007 Benton 13-007-
009 Blackford 13-009-
011 Boone 13-011-
013 Brown 13-013-
015 Carroll 13-015-
017 Cass 13-017-
019 Clark 13-019-
021 Clay 13-021-
023 Clinton 13-023-
025 Crawford 13-025-
027 Daviess 13-027-
029 Dearborn 13-029-
031 Decatur 13-031-
033 DeKalb 13-033-
035 Delaware 13-035-
037 Dubois 13-037-
039 Elkhart 13-039-
041 Fayette 13-041-
043 Floyd 13-043-
045 Fountain 13-045-
047 Franklin 13-047-
049 Fulton 13-049-
051 Gibson 13-051-
053 Grant 13-053-
055 Greene 13-055-
057 Hamilton 13-057-
059 Hancock 13-059-
061 Harrison 13-061-
063 Hendricks 13-063-
065 Henry 13-065-
067 Howard 13-067-
069 Huntington 13-069-
071 Jackson 13-071-
073 Jasper 13-073-
075 Jay 13-075-
077 Jefferson 13-077-
079 Jennings 13-079-
081 Johnson 13-081-
083 Knox 13-083-
085 Kosciusko 13-085-
087 LaGrange 13-087-
089 Lake 13-089-
091 LaPorte 13-091-
093 Lawrence 13-093-
095 Madison 13-095-
097 Marion 13-097-
099 Marshall 13-099-
101 Martin 13-101-
103 Miami 13-103-
105 Monroe 13-105-
107 Montgomery 13-107-
109 Morgan 13-109-
111 Newton 13-111-
113 Noble 13-113-
115 Ohio 13-115-
117 Orange 13-117-
119 Owen 13-119-
121 Parke 13-121-
123 Perry 13-123-
125 Pike 13-125-
127 Porter 13-127-
129 Posey 13-129-
131 Pulaski 13-131-
133 Putnam 13-133-
135 Randolph 13-135-
137 Ripley 13-137-
139 Rush 13-139-
141 St. Joseph 13-141-
143 Scott 13-143-
145 Shelby 13-145-
147 Spencer 13-147-
149 Starke 13-149-
151 Steuben 13-151-
153 Sullivan 13-153-
155 Switzerland 13-155-
157 Tippecanoe 13-157-
159 Tipton 13-159-
161 Union 13-161-
163 Vanderburgh 13-163-
165 Vermillion 13-165-
167 Vigo 13-167-
169 Wabash 13-169-
171 Warren 13-171-
173 Warrick 13-173-
175 Washington 13-175-
177 Wayne 13-177-
179 Wells 13-179-
181 White 13-181-
183 Whitley 13-183-

County names are the US Census names for these codes. The API standard does not promise the two match, so we checked them against state well records. Across 35 states, where this table names a county it matched the one the agency recorded on 85,091 of 85,100 wells. Offshore state and federal waters use their own pseudo-county codes, which are not listed here.

Finding the well itself

The API number stops at the county. It does not hold the well's coordinates, lease, survey section or operator. Those sit in the well record, which you find by searching the full number in the state agency's system. Search it at the Indiana oil and gas regulator.

Frequently asked questions

What is the API state code for Indiana?

13. API state codes run alphabetically from 01 for Alabama to 49 for Wyoming, then 50 for Alaska and 51 for Hawaii. They are not the Census FIPS state codes, which is a common source of wrong lookups.

How do I find the county from a Indiana API number?

Read digits three to five and find them in the table on this page. In 13-001-12345, the county code is 001, which is Adams County. If the code is missing from the table, it is usually an offshore area rather than an onshore county.

Does a Indiana API number give the well's exact location?

No. The number stops at the county. Coordinates, the lease and the survey location are in the well record held by the state agency, which you search with the full API number.

State codes: American Petroleum Institute Bulletin D12A well numbering standard. County names: US Census county FIPS names, checked against state well records. Reference generated .

How to cite this page

Sources: American Petroleum Institute Bulletin D12A well numbering standard; US Census county FIPS codes.

TetraSoft. (2026). Indiana API county codes. Reference generated 2026-09-24. https://tetrasoftco.com/tools/api-county-codes/indiana/