| Index | Decatur | Illinois | National |
| Average Test Scores | 10% | 33% | 48% |
| Student/Teacher ratio | 22:1 | 18:1 | 16:1 |
| Total public schools | 35 | 3,938 | 79,221 |
| Total private schools | 11 | 1,438 | 24,874 |
| Total post-secondary schools | 3 | 306 | 7,963 |
| Index | Decatur | Illinois | National |
| Completed 8th grade | 82.1% | 86.2% | 84.3% |
| Completed high school | 80.8% | 84.7% | 83.0% |
| Completed some college | 53.7% | 61.8% | 59.4% |
| Completed associate degree | 29.7% | 40.7% | 38.5% |
| Completed bachelors | 21.6% | 32.9% | 30.3% |
| Completed masters | 8.0% | 12.7% | 11.5% |
| Completed professional degree | 2.3% | 3.4% | 3.3% |
| Completed doctorate | 0.9% | 1.2% | 1.3% |
There are a total of 35 public schools, 11 private schools and 3 post-secondary schools in Decatur. Using the proficiency score averages, the average test scores for Decatur, IL schools is 10%. The average student to teacher ratio is 22:1. In Decatur, IL, an average of 82.1% of students have completed 8th grade and an average of 80.8% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Stonington, IL | 671 | 50% | 4.2% |
| Forsyth, IL | 3,474 | 48% | 1.0% |
| Cerro Gordo, IL | 1,275 | 45% | 7.3% |
| Mount Zion, IL | 5,707 | 44% | 8.9% |
| Oreana, IL | 954 | 41% | 14.6% |
| Decatur, IL | 71,857 | 10% | 79.2% |
| City | Population | Avg. Test Scores | National Avg. |
| Frederick, MD | 71,843 | 46% | 4.1% |
| Lauderhill, FL | 71,827 | 39% | 18.0% |
| Pawtucket, RI | 71,821 | 24% | 49.4% |
| Pittsburg, CA | 71,723 | 28% | 40.9% |
| Redlands, CA | 71,680 | 50% | 4.2% |
| Decatur, IL | 71,857 | 10% | 79.2% |
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