raatools/

💰 Finance

Calculadoras de préstamo, depreciación, energía y ahorro de combustible

Money calculations where seeing the working matters more than getting a number. Loan repayments, compound growth, salary conversions, running costs, and the everyday arithmetic of whether one price is really better than another.

These are informational tools, not advice. They are useful for understanding the shape of a decision — how much of a payment is interest, what a rate change does over twenty years — and they are not a substitute for the figures your lender, employer or tax authority gives you.

Which tool do I want?

If you…Use
You want repayments and total interest on a loanCalculadora de préstamo
You are projecting savings or investment growthCalculadora de interés compuesto
You need to compare an hourly rate to an annual salaryCalculadora de salario
You are working out take-home payCalculadora de nómina
Two package sizes and you want the real unit priceCalculadora de precio unitario
You want the running cost of an appliance or serverCosto de energía
You are checking what a discount actually savesComparador de descuentos
You are planning monthly spendingPlanificador de presupuesto

Compounding frequency changes the answer more than people expect

A "5% annual rate" is not one number. Compounded once a year it returns exactly 5%. Compounded monthly the effective rate is 5.12%; daily, 5.13%. Small differences — until you run them over decades, where they separate meaningfully.

This is why regulators require lenders to quote an effective annual rate alongside the nominal one. The nominal rate tells you what gets applied per period; the effective rate tells you what actually happens over a year, and only the second is comparable between products.

Worth knowing in the other direction too: on a long mortgage, the early payments are overwhelmingly interest, because interest is charged on the balance and the balance has barely moved. That is also why overpaying early is far more effective than overpaying late — every extra unit removes a balance that would otherwise have accrued interest for the entire remaining term.