Credit Card Monthly Flat-Fee Installment to True Effective APR (IRR) Calculator

Q: What is the rule-of-thumb multiplier to convert a 12-month flat rate to APR?

For a 12-month installment loan, multiply `Monthly Flat Rate × 12` by roughly `1.85` (`2n / (n + 1)`). Our calculator solves the exact root of the Net Present Value equation for complete precision.

Banks advertise "0.6% monthly installment fee" as if it were 7.2% APR—when the true effective APR exceeds 13%! Compute exact Newton-Raphson IRR across flat-fee installments and upfront fees.

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🔍 True APR & IRR Cashflow Detector

Credit Card Installment, Online Loan & Lease True APR (IRR / EAR) Calculator

Do not be fooled by "0.5% monthly flat fee" claims! Built on a Newton-Raphson cashflow solver, this detector exposes both Nominal Annualized APR and Compound Effective Annual Rate (EAR) across any upfront fees or deposits.

Quick Scenarios:

1. Loan Contract & Cashflow Parameters

Repayment Structure

Contract Principal (CNY)

Number of Periods

Quoted Flat Rate per Period (%)

Repayment Frequency

Upfront Origination / Service Fee (CNY)

Security Deposit (Refunded at End)

2. True Annualized IRR Verdict & Risk Rating

Nominal Annual APR (Simple IRR × 12)

13.03%

Periodic IRR: 1.086%

Effective Annual Rate (Compound EAR)

13.84%

vs Quoted Headline: 7.20%

Borrowing Cost Risk Thermometer:🟠 High-Cost Credit (12%–24% Caution)

<5% Low

5%~12% Normal

12%~24% High

>24% Danger

Net Cash Received at T=0 (After Fees/Deposit)¥50,000.00

Regular Periodic Payment¥4,466.67

Total Interest + Upfront Fees Paid¥3,600.00

Average Principal Occupied (Utilization)¥27,619.60 (55.2%)

3. Period-by-Period Cashflow & Imputed IRR Amortization Table

Period #0 net inflow: +¥50,000.00, followed by 12 repayment outflows.

Period	Net Cashflow	True Imputed Interest	True Principal Repaid	Remaining Net Principal
#0 (Disbursement)	+¥50,000.00	—	—	¥50,000.00
#1	¥-4,466.67	¥543.09	¥3,923.57	¥46,076.43
#2	¥-4,466.67	¥500.48	¥3,966.19	¥42,110.23
#3	¥-4,466.67	¥457.40	¥4,009.27	¥38,100.96
#4	¥-4,466.67	¥413.85	¥4,052.82	¥34,048.14
#5	¥-4,466.67	¥369.83	¥4,096.84	¥29,951.30
#6	¥-4,466.67	¥325.33	¥4,141.34	¥25,809.96
#7	¥-4,466.67	¥280.34	¥4,186.32	¥21,623.64
#8	¥-4,466.67	¥234.87	¥4,231.79	¥17,391.85
#9	¥-4,466.67	¥188.91	¥4,277.76	¥13,114.09
#10	¥-4,466.67	¥142.44	¥4,324.22	¥8,789.86
#11	¥-4,466.67	¥95.47	¥4,371.19	¥4,418.67
#12	¥-4,466.67	¥47.99	¥4,418.67	¥0.00

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Why a 0.6% Monthly Flat Fee Actually Costs Over 13% APR

In a flat-fee ("add-on interest") installment plan, you repay 1/12th of the principal every month—so your average borrowed balance over the year is roughly half the initial amount—yet the lender charges the monthly fee against 100% of the original balance every single month. Use this pre-loaded IRR detector to see the true effective APR in milliseconds.

Frequently Asked Questions (FAQ)

Q1 What is the rule-of-thumb multiplier to convert a 12-month flat rate to APR?

For a 12-month installment loan, multiply Monthly Flat Rate × 12 by roughly 1.85 (2n / (n + 1)). Our calculator solves the exact root of the Net Present Value equation for complete precision.

Credit Card Installment, Online Loan & Lease True APR (IRR / EAR) Calculator

1. Loan Contract & Cashflow Parameters

2. True Annualized IRR Verdict & Risk Rating

3. Period-by-Period Cashflow & Imputed IRR Amortization Table

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Wise Business — Global USD / EUR / GBP Accounts

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Why a 0.6% Monthly Flat Fee Actually Costs Over 13% APR

Frequently Asked Questions (FAQ)

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