The Formula and What Each Number Means

The math is straightforward: (Salary − Min) ÷ (Max − Min) × 100. A salary at the band minimum scores 0%, a salary at the midpoint scores 50%, and a salary at the maximum scores 100%.

Range penetration is sometimes preferred over compa-ratio when grades are wide, because it tells you about position within the band rather than position relative to a single midpoint figure. Wide bands can mask significant under- or over-payment when you only look at compa-ratio.

The Four Bands and What Each Tells You

Most comp teams treat the range as four meaningful zones:

• 0–33% (entry/learning): typically a brand-new hire or someone in training. Anyone tenured here is a flight risk.
• 34–66% (developing): employees building proficiency. Should be moving toward the upper half within 12–18 months.
• 67–99% (proficient): the target band for fully competent employees. Most of your workforce should sit here.
• 100% (maxed-out): the employee has hit the band ceiling. Either promote them, hold base and shift increases to bonus, or accept they have nowhere to grow inside this grade.

Range Penetration vs. Compa-Ratio — When to Use Which

Penetration is sensitive to grade width; compa-ratio is sensitive to midpoint. Run both. Penetration answers “where in the band”; compa-ratio answers “vs. market.” A salary can have a healthy compa-ratio (close to 100%) but uncomfortable penetration (above 90%) if the band is narrow — that’s an early signal the grade structure itself needs widening or the employee needs promotion. See our compa-ratio calculator for the other half of the picture.

Spotting Compression and Flight Risk

High penetration combined with long tenure is a signal — either this person should be promoted, or they’re going to leave. Low penetration combined with strong performance ratings is the inverse: an underpaid employee relative to their actual capability, almost always a retention risk if the gap is more than one merit cycle wide. Pulling penetration into your annual talent review (alongside performance and tenure) catches both patterns before they cost you the person.

Using Penetration in Merit Cycles

The most actionable use: constrain merit increases by current penetration. Employees at 90%+ get smaller raises (or a promotion conversation) so they don’t blow past the band. Employees below 50% get larger raises to bring them toward proficient. This single rule turns the merit cycle from a flat percentage exercise into a structural fix for under- and over-payment, without requiring any extra budget.

Common Mistakes

Three things go wrong repeatedly. First, treating 50% as the “right” answer — it isn’t; proficient employees should sit at 75–100%. Second, confusing penetration with compa-ratio and reporting one as if it were the other to leadership. Third, ignoring grade-width drift over time — if your bands haven’t been refreshed against market in three years, every penetration number you compute is against an outdated structure. Pair this calculator with a periodic review of the underlying pay structure.