| Index | Duncan | South Carolina | National |
| Average Test Scores | 54% | 47% | 48% |
| Student/Teacher ratio | 14:1 | 16:1 | 16:1 |
| Total public schools | 5 | 932 | 79,221 |
| Total private schools | 1 | 369 | 24,874 |
| Total post-secondary schools | n/a | 96 | 7,963 |
| Index | Duncan | South Carolina | National |
| Completed 8th grade | 81.6% | 83.0% | 84.3% |
| Completed high school | 80.3% | 81.6% | 83.0% |
| Completed some college | 46.8% | 56.6% | 59.4% |
| Completed associate degree | 21.5% | 35.6% | 38.5% |
| Completed bachelors | 18.6% | 26.5% | 30.3% |
| Completed masters | 3.7% | 9.6% | 11.5% |
| Completed professional degree | 1.8% | 2.5% | 3.3% |
| Completed doctorate | 0.2% | 1.1% | 1.3% |
There are a total of 5 public schools, 1 private schools and n/a post-secondary schools in Duncan. Using the proficiency score averages, the average test scores for Duncan, SC schools is 54%. The average student to teacher ratio is 14:1. In Duncan, SC, an average of 81.6% of students have completed 8th grade and an average of 80.3% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Reidville, SC | 1,317 | 72% | 50.0% |
| Taylors, SC | 23,107 | 69% | 43.6% |
| Mauldin, SC | 25,829 | 69% | 42.7% |
| Greer, SC | 32,229 | 64% | 33.0% |
| Simpsonville, SC | 23,200 | 63% | 31.7% |
| Duncan, SC | 3,556 | 54% | 11.6% |
| City | Population | Avg. Test Scores | National Avg. |
| Gallipolis, OH | 3,557 | 64% | 32.7% |
| Loxahatchee Groves, FL | 3,557 | 69% | 43.8% |
| Knox, IN | 3,553 | 40% | 17.0% |
| St. Anthony, ID | 3,552 | 39% | 18.1% |
| Farmersville, TX | 3,560 | 54% | 12.5% |
| Duncan, SC | 3,556 | 54% | 11.6% |
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