A letter grade is the at-a-glance summary the site readiness audit emits. It compresses the nine per-category scores into a single number, then into a letter:
| Score | Grade |
|---|---|
| 90-100 | A |
| 80-89 | B |
| 70-79 | C |
| 60-69 | D |
| below 60 | F |
What the score is actually
The overall score is not an average of the nine category scores. It is a flat average across every individual check the audit ran: a pass scores 1, a warning 0.5, a failure 0, and the total is divided by the number of checks.
A worked example. A scan returning 18 passes, 22 warnings and 10 failures across 50 checks scores (18 × 1) + (22 × 0.5) = 29, then 29 ÷ 50 = 58.
The consequence is the part worth internalising: categories are weighted by how many checks they contain, not equally. A category with seven checks moves the overall roughly seven times as much as a category with one. So fixing a security failure and fixing an international-targeting warning are not equivalent work, even when both show as a single red mark on the report — and the categories with the most checks are where the overall score actually lives.
When the grade is misleading
The grade is a useful headline but the per-category breakdown is where the actionable signal lives. A site can score a healthy overall grade while carrying a complete security failure, because a large number of trivial passes elsewhere outweighs a small number of serious failures. Always read past the letter — the per-category breakdown is what tells you whether the failures you have are cosmetic or structural.
For audit history, the grade is what we plot — the sparkline on the per-project audit page shows the letter on each tick, so a sudden drop is visible even at low resolution.