What This Calculator Measures
Estimate savings from an interest rate drop on loans or credit balances.
By combining practical inputs into a structured model, this calculator helps you move from vague estimation to clear planning actions you can execute consistently.
This calculator estimates savings by comparing interest costs at two rates.
How to Use This Well
- Enter balance and current rate.
- Add new rate and payment.
- Set remaining months and refi cost.
- Review savings and breakeven.
- Decide if timing works.
Formula Breakdown
Savings = interest(current) − interest(new)Worked Example
- $18,000 at 16% vs 12%.
- Monthly savings of ~ $60.
- Breakeven around 10 months.
Interpretation Guide
| Range | Meaning | Action |
|---|---|---|
| 0–6 mo | Fast breakeven. | Strong refi case. |
| 7–18 mo | Moderate. | Likely worthwhile. |
| 19–30 mo | Longer. | Check timeline. |
| 30+ mo | Slow. | Consider staying put. |
Optimization Playbook
- Lower rate: biggest impact.
- Reduce refi cost: improves breakeven.
- Keep payment: accelerate payoff.
- Compare timelines: consider remaining months.
Scenario Planning
- Baseline: current rate.
- Lower rate: reduce rate by 1%.
- Lower fees: reduce refi cost by $200.
- Decision rule: target breakeven under 18 months.
Common Mistakes to Avoid
- Ignoring refi fees.
- Changing payment assumptions.
- Overlooking remaining term.
- Forgetting rate type changes.
Implementation Checklist
- Confirm current rate and balance.
- Get new rate offer.
- List all fees.
- Compare breakeven to term.
Measurement Notes
Treat this calculator as a directional planning instrument. Output quality improves when your inputs are anchored to recent real data instead of one-off assumptions.
Run multiple scenarios, document what changed, and keep the decision tied to trends, not a single result snapshot.
FAQ
When is a rate drop worth it?
When breakeven is shorter than your remaining term.
Does payment matter?
Yes, keeping payment steady increases savings.
Should I include fees?
Yes, include all refi costs.