Formula
For a fixed-rate amortizing payment: payment = principal x monthlyRate / (1 - (1 + monthlyRate)^(-numberOfPayments)). Total interest = payment x numberOfPayments - principal.
Finance Calculator
Loan payment, interest and total-cost fields on one dedicated calculator page.
Worked example
For a $300,000 loan at 6.5% for 30 years, the monthly rate is 0.065 / 12 and the payment count is 360. The fixed-payment formula estimates about $1,896.20 per month before taxes, insurance or fees.
Professional note
Master’s Tip: compare both monthly payment and lifetime interest. A lower payment can still cost more if the term is stretched too far.
Regional and unit assumptions
Standard or basis: general fixed-rate finance arithmetic using monthly compounding/payment periods. It does not include taxes, insurance, variable rates, fees, legal advice or lender-specific rules unless entered separately.
Assumptions and limitations
- The example assumes a fixed rate and equal monthly payments.
- APR, compounding basis and fee treatment can differ by lender and region.
- Taxes, insurance, escrow, early repayment, redraw and offset features are not inferred.
- Finance results are estimates for planning and comparison, not lending advice.
Methodology & Accuracy
How this calculator is checked
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Formula used
For a fixed-rate amortizing payment: payment = principal x monthlyRate / (1 - (1 + monthlyRate)^(-numberOfPayments)). Total interest = payment x numberOfPayments - principal.
Standard or basis
Standard or basis: general fixed-rate finance arithmetic using monthly compounding/payment periods. It does not include taxes, insurance, variable rates, fees, legal advice or lender-specific rules unless entered separately.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master's Tip
Master’s Tip: compare both monthly payment and lifetime interest. A lower payment can still cost more if the term is stretched too far.
Related calculators
Questions
What does a finance calculator show?
It shows the relationship between principal, rate, term, payment, total paid and estimated interest.
Why can the monthly payment look affordable but still be expensive?
A longer term can reduce the payment while increasing the total interest paid over the life of the loan.
Does this replace a mortgage calculator?
No. Use the mortgage calculator when you need mortgage-specific extras such as taxes, insurance or housing-cost assumptions.
What should I compare between offers?
Compare payment, total interest, fees, term, flexibility and the assumptions behind the rate.
Calculation note
Finance calculators are most useful when they show both the monthly answer and the long-term cost. CalculationTime keeps those assumptions visible so a neat payment number does not hide the trade-off.