Sapi-an comprises 10 barangays with an estimated population of 30,523. 3 of its barangays (30%) are connectivity dead zones with no recorded cell tower from either the national registry or crowdsourced data.
| Barangay | Population | Towers | Coverage |
|---|---|---|---|
| Agsilab | 1,346 | 0 | Dead zone: no towers from any source |
| Agtatacay Norte | 1,093 | 0 | Dead zone: no towers from any source |
| Agtatacay Sur | 2,833 | 2 | Crowdsourced signal only (no registered tower) |
| Bilao | 3,209 | 4 | Crowdsourced signal only (no registered tower) |
| Damayan | 1,631 | 3 | Crowdsourced signal only (no registered tower) |
| Dapdapan | 2,522 | 2 | Crowdsourced signal only (no registered tower) |
| Lonoy | 3,081 | 0 | Dead zone: no towers from any source |
| Majanlud | 2,147 | 6 | Crowdsourced signal only (no registered tower) |
| Maninang | 6,445 | 26 | Crowdsourced signal only (no registered tower) |
| Poblacion | 6,216 | 17 | Crowdsourced signal only (no registered tower) |