| Index | Mercer Island | Washington | National |
| Average Test Scores | 85% | 54% | 48% |
| Student/Teacher ratio | 20:1 | 20:1 | 16:1 |
| Total public schools | 7 | 1,991 | 79,221 |
| Total private schools | 6 | 548 | 24,874 |
| Total post-secondary schools | n/a | 147 | 7,963 |
| Index | Mercer Island | Washington | National |
| Completed 8th grade | 98.2% | 87.5% | 84.3% |
| Completed high school | 98.1% | 86.6% | 83.0% |
| Completed some college | 92.9% | 67.7% | 59.4% |
| Completed associate degree | 82.9% | 43.3% | 38.5% |
| Completed bachelors | 78.2% | 33.6% | 30.3% |
| Completed masters | 36.7% | 12.3% | 11.5% |
| Completed professional degree | 14.8% | 3.6% | 3.3% |
| Completed doctorate | 4.1% | 1.5% | 1.3% |
There are a total of 7 public schools, 6 private schools and n/a post-secondary schools in Mercer Island. Using the proficiency score averages, the average test scores for Mercer Island, WA schools is 85%. The average student to teacher ratio is 20:1. In Mercer Island, WA, an average of 98.2% of students have completed 8th grade and an average of 98.1% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Medina, WA | 3,283 | 91% | 88.5% |
| Sammamish, WA | 65,265 | 86% | 78.2% |
| Redmond, WA | 67,959 | 83% | 73.1% |
| Bainbridge Island, WA | 24,859 | 81% | 67.9% |
| Fall City, WA | 2,357 | 78% | 63.0% |
| Mercer Island, WA | 25,820 | 85% | 77.8% |
| City | Population | Avg. Test Scores | National Avg. |
| Kankakee, IL | 25,818 | 22% | 54.5% |
| Mauldin, SC | 25,829 | 69% | 42.7% |
| Holbrook, NY | 25,794 | 48% | 1.0% |
| Lebanon, PA | 25,779 | 45% | 5.9% |
| Lemoore, CA | 25,867 | 42% | 12.4% |
| Mercer Island, WA | 25,820 | 85% | 77.8% |
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