| Index | Johnston | South Carolina | National |
| Average Test Scores | 39% | 47% | 48% |
| Student/Teacher ratio | 15:1 | 16:1 | 16:1 |
| Total public schools | 4 | 932 | 79,221 |
| Total private schools | 1 | 369 | 24,874 |
| Total post-secondary schools | n/a | 96 | 7,963 |
| Index | Johnston | South Carolina | National |
| Completed 8th grade | 68.2% | 83.0% | 84.3% |
| Completed high school | 66.8% | 81.6% | 83.0% |
| Completed some college | 23.2% | 56.6% | 59.4% |
| Completed associate degree | 12.2% | 35.6% | 38.5% |
| Completed bachelors | 8.8% | 26.5% | 30.3% |
| Completed masters | 4.1% | 9.6% | 11.5% |
| Completed professional degree | 0.3% | 2.5% | 3.3% |
| Completed doctorate | 0.3% | 1.1% | 1.3% |
There are a total of 4 public schools, 1 private schools and n/a post-secondary schools in Johnston. Using the proficiency score averages, the average test scores for Johnston, SC schools is 39%. The average student to teacher ratio is 15:1. In Johnston, SC, an average of 68.2% of students have completed 8th grade and an average of 66.8% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Saluda, SC | 3,603 | 42% | 11.7% |
| Edgefield, SC | 4,800 | 40% | 17.7% |
| Monetta, SC | 253 | 35% | 27.6% |
| Trenton, SC | 266 | 29% | 40.6% |
| Ridge Spring, SC | 676 | 27% | 43.8% |
| Johnston, SC | 2,556 | 39% | 18.4% |
| City | Population | Avg. Test Scores | National Avg. |
| Lake City, AR | 2,556 | 50% | 4.7% |
| Eddyville, KY | 2,556 | 57% | 18.1% |
| La Porte City, IA | 2,556 | 77% | 60.4% |
| Norway, ME | 2,556 | 32% | 34.4% |
| Pageland, SC | 2,556 | 46% | 5.2% |
| Johnston, SC | 2,556 | 39% | 18.4% |
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