| School | Roll number | County | Total (latest year) | Latest average class size | Largest class | Classes 30+ |
|---|---|---|---|---|---|---|
| Castlebar Primary School | 20562H | Mayo | 864 | 25.03 | 28 | 0 |
| ST. JOSEPHS N. S. | 20089H | Mayo | 451 | 24.33 | 30 | 4 |
| SCOIL IOSA | 20142I | Mayo | 385 | 18.75 | 24 | 0 |
| BREAFFY N S | 13781F | Mayo | 377 | 22.81 | 28 | 0 |
| SCOIL PHADRAIG | 20230F | Mayo | 338 | 24.14 | 27 | 0 |
| Claremorris National School | 20585T | Mayo | 314 | 20.53 | 25 | 0 |
| ST PETERS NS | 19916J | Mayo | 271 | 22.58 | 31 | 3 |
| NEWPORT CENTRAL | 19451O | Mayo | 243 | 22.50 | 33 | 1 |
| GAELSCOIL RAIFTEIRÍ | 19832D | Mayo | 229 | 25.44 | 32 | 2 |
| BALLYVARY CENTRAL N S | 19402B | Mayo | 223 | 26.62 | 31 | 2 |
| BARNACARROLL CENTRAL NS | 19710M | Mayo | 208 | 26.00 | 32 | 2 |
| S N CNOC RUSCAIGHE | 18712L | Mayo | 206 | 22.25 | 27 | 0 |
| S N NAOMH COLM CILLE | 13145A | Mayo | 206 | 25.75 | 32 | 2 |
| Scoil Naisiunta Balla Aluinn | 17119T | Mayo | 202 | 24.50 | 30 | 1 |
| BEACAN MIXED N S | 13659I | Mayo | 177 | 25.29 | 27 | 0 |
| KNOCK N S | 16122D | Mayo | 152 | 22.33 | 29 | 0 |
| BRACKLOON N S | 04796R | Mayo | 145 | 23.33 | 28 | 0 |
| SN na hAille | 12350T | Mayo | 140 | 23.33 | 33 | 1 |
| BALLINDINE B N S | 01676P | Mayo | 138 | 27.60 | 34 | 3 |
| S N FAITCHE | 13555T | Mayo | 137 | 27.40 | 38 | 2 |
| S N PADRAIG NAOFA | 20037L | Mayo | 133 | 20.83 | 24 | 0 |
| ROBEEN CENTRAL N S | 19394F | Mayo | 127 | 25.40 | 36 | 1 |
| ST PATRICKS CENTRAL NS | 19911W | Mayo | 117 | 22.40 | 26 | 0 |
| BALLINTUBBER N S | 07374G | Mayo | 113 | 27.00 | 32 | 1 |
| ST JOSEPHS N S | 13152U | Mayo | 111 | 21.00 | 31 | 1 |
| S N BEAL CARADH | 17585C | Mayo | 109 | 21.80 | 27 | 0 |
| S N UILEOG DE BURCA | 19972T | Mayo | 105 | 21.00 | 28 | 0 |
| S N BRIGHDE | 16756V | Mayo | 103 | 20.60 | 24 | 0 |
| MYNA N S | 16618J | Mayo | 102 | 25.50 | 32 | 1 |
| SN Beal Atha na hEin | 13444K | Mayo | 95 | 23.75 | 28 | 0 |
| Scoil Náisiúnta Thuar Mhic Éadaigh | 20256A | Mayo | 94 | 23.50 | 27 | 0 |
| ST MARYS N S | 15030Q | Mayo | 93 | 23.25 | 25 | 0 |
| St Paul's National School | 17562N | Mayo | 89 | 22.25 | 25 | 0 |
| MOUNT PLEASANT N S | 13500R | Mayo | 86 | 21.50 | 28 | 0 |
| S N MAINISTIR MUIGHEO | 14205U | Mayo | 84 | 21.00 | 22 | 0 |
| SCOIL CHOMAIN NAOFA | 17082W | Mayo | 82 | 20.50 | 27 | 0 |
| MEELICKMORE N S | 12173A | Mayo | 81 | 20.25 | 22 | 0 |
| S N Realt na Mara | 17176I | Mayo | 77 | 19.25 | 25 | 0 |
| S N CHLUAIN LUIFIN | 18922W | Mayo | 75 | 18.75 | 24 | 0 |
| S N GORT SCEICHE | 18880J | Mayo | 75 | 18.75 | 23 | 0 |
| IRISHTOWN N S | 14808E | Mayo | 70 | 23.33 | 26 | 0 |
| S N TEAGHLAIGH NAOFA | 19324H | Mayo | 67 | 21.00 | 25 | 0 |
| S N B CURNANOOL | 14497N | Mayo | 66 | 22.00 | 23 | 0 |
| S N LAINN CILLE | 16904K | Mayo | 66 | 22.00 | 28 | 0 |
| S N NAOMH PADRAIG SAILE | 16052I | Mayo | 65 | 21.67 | 27 | 0 |
| S N Toin na Gaoithe | 16113C | Mayo | 61 | 20.33 | 24 | 0 |
| St Mary's National School | 20499D | Mayo | 51 | 17.00 | 21 | 0 |
| CLOGHER NS | 17482P | Mayo | 50 | 16.67 | 20 | 0 |
| MUIRISC NS | 16832L | Mayo | 49 | 16.33 | 21 | 0 |
| S N NAOMH FEICHIN | 07075T | Mayo | 47 | 15.67 | 18 | 0 |
| S N an Teaghlaigh | 18562S | Mayo | 45 | 15.00 | 16 | 0 |
| CARRAHOLLY N S | 17483R | Mayo | 42 | 14.00 | 16 | 0 |
| S N COILL AN BHAILE | 14064F | Mayo | 41 | 20.50 | 24 | 0 |
| S N FIONDALBHA | 17678J | Mayo | 37 | 18.50 | 23 | 0 |
| S N CEATHRU AN CHLOCHAR | 12816Q | Mayo | 35 | 17.50 | 18 | 0 |
| S N TEACH CAOIN | 17301I | Mayo | 33 | 16.50 | 17 | 0 |
| CARRAKENNEDY N S | 15866A | Mayo | 32 | 16.00 | 17 | 0 |
| ST JOHNS NS | 15539I | Mayo | 32 | 16.00 | 18 | 0 |
| LECANVEY N S | 13797U | Mayo | 31 | 15.50 | 21 | 0 |
| S N DUMHACH | 18082E | Mayo | 28 | 14.00 | 23 | 0 |
| S N GORT AN EADAIN | 13773G | Mayo | 28 | 14.00 | 14 | 0 |
| S N COLM NAOFA | 17682A | Mayo | 27 | 13.50 | 16 | 0 |
| DOOKINELLA N.S. | 14873P | Mayo | 26 | 13.00 | 16 | 0 |
| BURRISCARRA N S | 05756K | Mayo | 23 | 11.50 | 12 | 0 |
| S N NAOMH BRID C | 18503C | Mayo | 21 | 10.50 | 15 | 0 |
| ACHILL SOUND CONVENT NS | 14863M | Mayo | 20 | 7.00 | 8 | 0 |
| S N AN COILL MHOR | 17321O | Mayo | 17 | 8.50 | 9 | 0 |
| VALLEY N S | 16379R | Mayo | 17 | 8.50 | 11 | 0 |
| CRIMLIN N S | 15967G | Mayo | 15 | 7.50 | 8 | 0 |
| SN Baile Cuisin | 18876S | Mayo | 13 | 6.50 | 8 | 0 |
| GORTJORDAN N S | 14534Q | Mayo | 11 | 5.50 | 6 | 0 |
| ST PATRICKS NS | 13311O | Mayo | 11 | 5.50 | 7 | 0 |
| LEHINCH N S | 05120L | Mayo | 8 | 8.00 | 8 | 0 |
| S N COILL MOR | 17039V | Mayo | 6 | 6.00 | 6 | 0 |
| ST COLUMBAS N.S. | 13174H | Mayo | 3 | 3.00 | 3 | 0 |