How interest, amortization and outstanding balance work
See how each payment is split, why interest changes and how the outstanding balance evolves through a mortgage.
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A path to understanding financing
Begin with the basics, then move to comparisons and extra amortization.
SAC table: how it works and how to calculate it
Understand constant amortization under SAC, calculate interest and payments, and follow the outstanding balance curve.
Read guide →Price table: formula, advantages and limitations
Calculate a Price payment and understand how interest and amortization move within a level financial payment.
Read guide →SAC or Price: compare the same financing
Compare SAC and Price side by side while keeping exactly the same amount, term and interest rate.
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How interest, amortization and outstanding balance work
See how each payment is split, why interest changes and how the outstanding balance evolves through a mortgage.
Read guide →SAC table: how it works and how to calculate it
Understand constant amortization under SAC, calculate interest and payments, and follow the outstanding balance curve.
Read guide →Price table: formula, advantages and limitations
Calculate a Price payment and understand how interest and amortization move within a level financial payment.
Read guide →SAC or Price: compare the same financing
Compare SAC and Price side by side while keeping exactly the same amount, term and interest rate.
Read guide →Reduce the term or lower the payment: what changes
Compare using BRL 20,000 in month 60 to shorten the contract or reduce the remaining payments.
Read guide →What is the best day to make an extra payment on a loan?
Separate the due date, payment date and reference date to find when an extra payment actually starts reducing the cost of a loan.
Read guide →Convert nominal and effective annual rates to monthly rates
Distinguish nominal from effective rates and correctly convert annual percentages to a monthly period.
Read guide →What CET is and why it matters more than the advertised rate
Understand Total Effective Cost, which cash flows enter it and why this simulator does not calculate regulatory CET.
Read guide →How TR changes a mortgage's outstanding balance
Compare the same financing with and without TR adjustment and understand the simulator's conservative assumption.
Read guide →Why a lender's payment may differ from the simulator
Reconcile rates, dates, insurance, fees, indexation and rounding when a contract payment does not match an estimate.
Read guide →How to compare two mortgage proposals
Build one table for rate, CET, index, costs, initial payment and estimated total across two proposals.
Read guide →How to simulate an FGTS amortization
Model FGTS as an extra amortization and compare term and payment reduction without confusing simulation with eligibility.
Read guide →Common mistakes when using a financing simulator
Avoid mixing monthly and annual rates, ignoring TR and costs, or selecting the wrong extra-amortization goal.
Read guide →No guide matches the selected search and filter.
Calculated scenarios
Ready-made simulations
Inspect the numbers, compare results, and open the scenario in the simulator.
BRL 300,000 over 360 months under SAC
A complete BRL 300,000 SAC example without indexation or extra costs, using the current BCB median.
- First payment
- R$4,343.33
- Total interest
- R$633,557.33
BRL 300,000 over 360 months under Price
A complete BRL 300,000 Price example with the same term and rate as the SAC example.
- First payment
- R$3,564.12
- Total interest
- R$983,060.05
Effect of amortizing BRL 20,000 in year five
Compare SAC with no contribution and with BRL 20,000 in month 60 to reduce the term.
- First payment
- R$4,343.33
- Total interest
- R$482,624.53
BRL 500 monthly amortization
See the effect of adding BRL 500 from the first month to reduce the term of a SAC loan.
- First payment
- R$4,843.33
- Total interest
- R$255,689.39
Reduce term or reduce payment
Apply the same BRL 20,000 in month 60 and compare the two amortization goals.
- First payment
- R$4,343.33
- Total interest
- R$482,624.53
Scenario with and without TR adjustment
Compare SAC with zero adjustment and with the highest annual-window TR reference repeated monthly.
- First payment
- R$3,689.82
- Total interest
- R$643,356.93