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Cash or installments calculator

Find out whether to pay cash (with a discount) or pay in installments and keep your money invested.

$
$
%/mo

What you'd earn investing (monthly)

Better to pay CASH
saves $57.37
Cash price$900.00
Total in installments (10×)$1,000.00
Installments at present value$957.37
Equivalent cash discount10%

If your money earns interest, paying interest-free installments and investing can beat the cash discount. We compare the cash price with the present value of the installments.

Interactive lesson: The debt that never ends Paying every month while the balance stays put isn't your imagination. Find the invisible line between paying and progressing. Glossary · MoneyMojisPay cash or invest the difference? That is opportunity cost.

How the calculation works

"Interest-free installments" are rarely truly free. The reason is the time value of money: R$100 today is worth more than R$100 in 10 months, because today you can invest it.

The calculator brings all installments to present value, using the rate your money would earn:

PV = installment × (1 − (1 + i)⁻ⁿ) ÷ i

How to decide

  • Cash price < present value of installments → paying cash wins.
  • Cash price ≥ PV of installments → pay in installments and keep the money invested.

Step-by-step example

R$900 cash or 10× R$100 (= R$1,000), money earning 0.8%/mo:

  1. PV of ten R$100 installments ≈ R$956
  2. Cash costs R$900 < R$956 → cash wins.

Practical rule

Always ask for the cash discount. If it beats what your money would earn, pay cash. Otherwise, split it interest-free and invest the difference.

Examples

  • R$900 cash vs 10× R$100 at 0.8%/mo: PV ≈ R$956 → cash wins.
  • No discount (R$1,000 cash vs 10× R$100): installments + investing win.

Frequently asked questions

Are interest-free installments always better?

If you invest the money, usually yes — but only if the cash discount is small and you actually invest the difference.

What rate should I use?

The rate your money would safely earn with liquidity — e.g., a CDB or Treasury monthly rate. Avoid risky-investment rates.

Worth splitting if I won't invest the difference?

Then the advantage disappears. If the money would sit idle, the cash discount almost always wins.

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Updated on June 18, 2026 · by Rafael Rossi · Methodology & sources