| Index | St. Marys | Ohio | National |
| Average Test Scores | 70% | 61% | 48% |
| Student/Teacher ratio | 20:1 | 17:1 | 16:1 |
| Total public schools | 5 | 3,650 | 79,221 |
| Total private schools | 1 | 1,000 | 24,874 |
| Total post-secondary schools | n/a | 393 | 7,963 |
| Index | St. Marys | Ohio | National |
| Completed 8th grade | 86.6% | 86.9% | 84.3% |
| Completed high school | 84.5% | 85.6% | 83.0% |
| Completed some college | 42.7% | 55.7% | 59.4% |
| Completed associate degree | 23.4% | 35.1% | 38.5% |
| Completed bachelors | 11.6% | 26.7% | 30.3% |
| Completed masters | 2.9% | 10.0% | 11.5% |
| Completed professional degree | 0.3% | 2.7% | 3.3% |
| Completed doctorate | 0.1% | 1.1% | 1.3% |
There are a total of 5 public schools, 1 private schools and n/a post-secondary schools in St. Marys. Using the proficiency score averages, the average test scores for St. Marys, OH schools is 70%. The average student to teacher ratio is 20:1. In St. Marys, OH, an average of 86.6% of students have completed 8th grade and an average of 84.5% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Minster, OH | 2,784 | 90% | 87.0% |
| Fort Loramie, OH | 1,430 | 89% | 84.4% |
| New Bremen, OH | 2,798 | 87% | 81.8% |
| St. Henry, OH | 2,738 | 85% | 77.8% |
| Botkins, OH | 1,151 | 84% | 75.5% |
| St. Marys, OH | 8,227 | 70% | 45.5% |
| City | Population | Avg. Test Scores | National Avg. |
| Brazil, IN | 8,225 | 54% | 13.2% |
| Ketchikan, AK | 8,230 | 43% | 10.4% |
| Mahtomedi, MN | 8,232 | 77% | 59.4% |
| Temple Hills, MD | 8,221 | 18% | 63.1% |
| Jefferson City, TN | 8,220 | 30% | 37.8% |
| St. Marys, OH | 8,227 | 70% | 45.5% |
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