Loan Comparison Calculator
Compare up to four loans side by side — interest rates, fees, repayments, and total cost of borrowing. Make an informed decision before signing up.
About this calculator
This calculator uses loan comparison methodology (APR). Reference: Standard APR formula. Last consulted 20 March 2026.
What to compare beyond the rate
General principles 2026- •Headline interest rate: Don't compare alone!
- •Establishment fee: $0–$500
- •Monthly admin fee: $0–$15
- •Early repayment fee: Varies (some $0, some 1-2%)
- •APR (true rate inc fees): Lender MUST disclose under CCCFA
- •Total cost over life: Best single comparison metric
Source: ComCom — Credit
Disclaimer
This calculator provides estimates for general information purposes only. Results are based on standard formulas and may not reflect your individual circumstances. Always consult a qualified professional for advice specific to your situation.
How to compare loan offers
Two loans at the same rate can differ in total cost if terms, fees, or compounding differ. Compare total cost, not just rate or monthly payment.
- 1
Calculate PMT for each loan
PMT = principal × i × (1+i)^n ÷ ((1+i)^n − 1)
Same formula, different inputs.
- 2
Total cost over loan life
Total_cost = PMT × n + setup_fees + admin_fees
Setup fees ($200-500) and monthly admin fees ($5-15) add up.
- 3
Compare APR (true cost)
APR = annualised rate including all fees
APR > headline rate when fees are high. Demand APR disclosure.
Worked example
Inputs: Loan A: 10% / 5yr / no fees. Loan B: 9.5% / 5yr / $300 setup + $10/mo admin
Result: Loan A total: $19,135. Loan B total: $19,025 — only $110 saving despite lower rate.
Frequently Asked Questions
How do I compare loans in NZ?
How does a comparison rate help me pick the right loan?
Should I choose a shorter or longer loan term?
What is the total interest cost over a loan's life?
Compares two or more loan options side-by-side — different rates, terms, or loan amounts — to find the cheapest total cost over the full term.
How this calculator works
For each option: monthly payment = P × (r(1+r)^n) / ((1+r)^n − 1). Total cost = monthly payment × n. Total interest = total cost − principal. Lower monthly payments from longer terms usually mean higher total interest.
Loan Comparison Key Facts
| 1% rate difference on $400k 25yr mortgage | ~$80,000 difference in total interest |
| Shorter term effect | Higher monthly payments but lower total interest |
| Revolving credit | Can reduce interest if balance actively managed |
Always compare total cost of credit, not just monthly payments. Longer terms can significantly increase total interest paid.
Worked Examples
$400,000 mortgage: 7.0% over 25 years vs 6.5% over 25 years
At 7%: $2,828/month, total interest $448,400. At 6.5%: $2,706/month, total interest $411,800. Saving: $36,600 over the term.
- Option A: $400,000 at 7.0% for 25 years (300 months)
- Monthly rate: 7% / 12 = 0.5833%
- Monthly payment: $400,000 × (0.005833 × 1.005833^300) / (1.005833^300 - 1) = $2,828
- Total repaid: $2,828 × 300 = $848,400
- Total interest: $848,400 - $400,000 = $448,400
- Option B: $400,000 at 6.5% for 25 years
- Monthly rate: 6.5% / 12 = 0.5417%
- Monthly payment ≈ $2,706
- Total repaid: $2,706 × 300 = $811,800
- Total interest: $811,800 - $400,000 = $411,800
- Interest saving by choosing 6.5%: $448,400 - $411,800 = $36,600
Built and maintained by Konstantin Iakovlev. Data sourced from the IRD and official New Zealand government sources.
Last reviewed: