Credit Score Impact Estimator
Estimate how key financial actions—paying down debt, opening new accounts, missing payments—affect your FICO credit score across all five scoring categories.
Formula & Model
This estimator uses the FICO scoring framework with five weighted categories:
- Payment History (35%): Score ratio = max(0, 1 − missed_payments × 0.12). Each missed payment in the last 24 months reduces this component by 12%.
- Credit Utilization (30%): Piecewise linear penalty function: full score (util ≤ 10%), gradual decline to 85% at 30%, 50% at 50%, 10% at 75%, 0% at 100%. Applied to both current and post-paydown utilization to compute the delta.
- Length of Credit History (15%): Weighted blend — oldest account age (60%) + average account age (40%) — each mapped via a piecewise curve (e.g., 10+ years oldest = 90% of max).
- New Credit (10%): Inquiry ratio = max(0, 1 − inquiries × 0.15); new account ratio = max(0, 1 − new_accounts × 0.10). Combined as 60% inquiry + 40% new accounts.
- Credit Mix (10%): Fixed ratios: 1 type = 40%, 2 = 65%, 3 = 85%, 4+ = 100%.
Score reconstruction: Estimated_Score = 300 + Σ(component_ratio × weight × 550). A calibration offset aligns the model output to the user's stated current score. The post-paydown score applies only the utilization delta on top of the calibrated baseline.
Score range: 300 (minimum) to 850 (maximum) = 550 usable points.
Assumptions & References
- Based on the FICO® Score model, the most widely used credit scoring model in the U.S. (used in 90%+ of lending decisions).
- FICO weights sourced from: myFICO.com — "What's in my FICO Scores?" (myfico.com/credit-education/whats-in-your-credit-score).
- Utilization thresholds (10%, 30%) reflect FICO's published guidance that scores are maximized below 10% utilization.
- Missed payment penalty (≈12% per occurrence) is derived from FICO's published impact ranges: a single 30-day late payment can drop a 780 score by 90–110 points (~14% of range).
- Hard inquiry impact (~5–10 points each) per FICO's published guidance; modeled as 15% per inquiry on the new credit component.
- This tool provides estimates only. Actual FICO scores depend on proprietary algorithms, exact account history, and data from all three bureaus (Equifax, Experian, TransUnion).
- VantageScore 3.0/4.0 uses similar but not identical weights; this model targets FICO 8, the most common version.
- Score changes from paydown are typically reflected within 30–60 days after the creditor reports the new balance.