| Index | St. Marys | Iowa | National |
| Average Test Scores | n/a | 69% | 48% |
| Student/Teacher ratio | n/a | 13:1 | 16:1 |
| Total public schools | n/a | 1,101 | 79,221 |
| Total private schools | n/a | 208 | 24,874 |
| Total post-secondary schools | n/a | 96 | 7,963 |

| Index | St. Marys | Iowa | National |
| Completed 8th grade | 97.6% | 89.2% | 84.3% |
| Completed high school | 97.6% | 87.7% | 83.0% |
| Completed some college | 75.6% | 59.8% | 59.4% |
| Completed associate degree | 35.7% | 38.4% | 38.5% |
| Completed bachelors | 28.0% | 27.2% | 30.3% |
| Completed masters | 7.7% | 8.7% | 11.5% |
| Completed professional degree | 0.0% | 2.7% | 3.3% |
| Completed doctorate | 0.0% | 1.1% | 1.3% |
There are a total of n/a public schools, n/a private schools and n/a post-secondary schools in St. Marys. Using the proficiency score averages, the average test scores for St. Marys, IA schools is n/a. The average student to teacher ratio is n/a. In St. Marys, IA, an average of 97.6% of students have completed 8th grade and an average of 97.6% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Norwalk, IA | 11,804 | 81% | 67.7% |
| Martensdale, IA | 518 | 76% | 57.8% |
| Indianola, IA | 16,415 | 74% | 54.0% |
| Carlisle, IA | 4,329 | 72% | 49.3% |
| Winterset, IA | 5,460 | 70% | 46.4% |
| St. Marys, IA | 188 | n/a |
| City | Population | Avg. Test Scores | National Avg. |
| Kelly, WY | 188 | 70% | 45.8% |
| Carpenter, WY | 188 | 50% | 4.2% |
| Litchfield, CA | 188 | 35% | 28.1% |
| Fort Apache, AZ | 188 | 5% | 89.6% |
| San Simon, AZ | 188 | 43% | 11.5% |
| St. Marys, IA | 188 | n/a |