Installment vs Cash Calculator: True Cost and APR

Compare the cash price with an installment plan in Egypt or Saudi Arabia: total paid, extra over cash, flat rate, and the annual percentage rate (APR) worked out with the present-value method.

We store nothing you type; everything runs in your browser. The default numbers are a worked example, not an offer from any store.

How it works

• Amount financed = cash price − down payment.
• Total paid = down payment + fees + (installment × months).
• Flat rate = (installments + fees − amount financed) ÷ amount financed ÷ years. Many stores advertise this number; it understates the real cost because you repay the principal gradually.
• APR: we solve for the monthly rate r at which the present value of all installments equals what you actually received (amount financed minus upfront fees), then multiply by 12. This is the present-value method required by the Saudi Central Bank (SAMA) rules for calculating APR.
• Effective annual rate = (1 + r)^12 − 1.

Worked example

A device costing 30,000 cash, no down payment, 12 × 3,000: total 36,000 (20% extra). The flat rate is 20% a year, but the APR is about 35% because you repay principal every month. Try it in the calculator.

Sources

• SAMA Rulebook: Rules Governing Calculation of Annual Percentage Rate (APR) — present-value method; all mandatory fees included
• SAMA Rulebook: Regulations for Consumer Financing — APR disclosure duty

Sources checked: 2026-10-25

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<a href="https://kobonatak.com/en/tools/installment-vs-cash/">Installment vs Cash Calculator: True Cost and APR</a> — Kobonatak

FAQ

Why is the APR different from the rate the store advertises?

Stores often quote a flat rate on the full amount for the whole term. You repay part of the principal every month, so the average balance is lower and the true annual cost is higher, often close to double in short plans.

What if the plan is 0% interest?

If installments plus fees equal the cash price, the calculator shows zero interest. Watch admin fees: enter them in the fee box, because they make a "0%" plan cost money.

Does it work for Egypt and Saudi Arabia?

Yes. The maths is the same; just pick the currency. In Saudi Arabia, SAMA requires lenders to disclose the APR, so compare our number with the one in your contract.

Do you store my data?

No. No number is sent to any server.