loanRRSO()
Compute APR (RRSO) from loan amount, nominal rate, payment count, and fees — for consumer-credit calculators that must show annual percentage rate alongside installment amounts.
Syntax
Every formula in Calcopolis must start with = in the Value field:
= loanRRSO(amount, interestRate, payments, paymentsPerYear, commission, installments)
| Part | Rule |
|---|---|
| Function name | loanRRSO — camelCase |
interestRate |
Nominal annual rate as decimal (0.05 = 5%) |
payments |
Number of installments in the schedule |
paymentsPerYear |
Payments per year (12 for monthly) |
| Optional | commission, installments ("EQUAL" / "DECREASING") |
| Return value | APR as a number (e.g. 5.25 means 5.25% — display with a percent pipe or label) |
Valid examples
= loanRRSO(loan_amount, interest_rate/100, term_months, 12)
= roundTo(loanRRSO(loan_amount, interest_rate/100, term_months, 12, 0.02), 2)
Invalid / unsupported
| Don't write | Why |
|---|---|
paymentsPerYear omitted |
Always pass payments per year (usually 12) |
Confusing with nominal rate |
RRSO includes fees and schedule; it can differ from the headline interest_rate |
Parameters
| Argument | Description |
|---|---|
amount |
Loan principal. |
interestRate |
Nominal annual rate as decimal. |
payments |
Count of installments (same as months for monthly loans). |
paymentsPerYear |
12 for monthly, 4 for quarterly, etc. |
commission |
Up-front fee as decimal of principal. |
installments |
"EQUAL" or "DECREASING". |
When to use loanRRSO()
Use on regulated credit or comparison calculators:
| Situation | What loanRRSO() does |
|---|---|
| RRSO / APR line | Mandatory disclosure next to installment |
| Compare bank offers | Same principal, different fees |
| Quarterly loans | Set paymentsPerYear to 4 |
Show nominal rate from the form and RRSO from this function so visitors see both figures.
Practical examples (ecommerce & leads)
1. Monthly consumer loan (Poland-style)
| Variable | Formula |
|---|---|
monthly_payment |
= roundTo(loanInstallmentAmount(loan_amount, interest_rate/100, term_months), 2) |
rrso |
= roundTo(loanRRSO(loan_amount, interest_rate/100, term_months, 12), 2) |
In Custom Text: RRSO: {{ rrso | percent:2 }} or label as {{ rrso }}% depending on your copy.
2. Loan with 2% commission
| Variable | Formula |
|---|---|
rrso |
= roundTo(loanRRSO(loan_amount, interest_rate/100, term_months, 12, 0.02), 2) |
Where to use it
| Location | Supported |
|---|---|
| Result widget Value | Yes — = ... formulas |
| Standalone variable (Variables tab) | Yes |
| Number / other input default Value | Yes, if formula-driven |
| Visibility formula | Yes |
| Custom Text / Table cells | No — use {{ }} templates there, not = functions |
After editing, run Calculate (or enable Run calculation on load in project Options) to refresh results.
Related
- [
loanTotalCost()](/docs/reference/formulas/loan-total-cost-function/) - [
loanInstallmentAmount()](/docs/reference/formulas/loan-installment-amount-function/) - Understanding Formulas and Variables —
=syntax and variables - Building Your First Calculator — end-to-end quote calculator