Rule of 78 Loan Calculator


You think normal amortized loans are complicated? How about these bizarre Rule of 78 loans?. Here the amount of your interest paid each month is determined using a fixed linear scale, and the annualized interest rate actually changes each month. I could explain it all out, but I don't want anyone to fall asleep and drop their mouse on the floor! Just put in some numbers and find out for yourself.
UPDATE: November 2008 - I was just notified that my annual interest rate calculation has been wrong for the past several years. Why didn't anybody else ever tell me? (Thanks, Steve!). In any case, now I instead print the annualized interest rate for each month as it slowly decreases over time. I have also removed the "Annual Interest Rate" option which was incorrect.


Loan Amount
Number of Months:


Monthly Payment100
Total Finance Charge 200.00

For 12 months, the magic rule number is 78

Payment Schedule

MonthStart BalanceInterestMonthly RatePrincipalEnd BalanceCum. Int. PaidInterest left to Pay
11000 30.7736.9231 % 69.23 930.77 30.77 169.23
2 930.77 28.2136.3636 % 71.79 858.98 58.98 141.02
3 858.98 25.6435.8207 % 74.36 784.62 84.62 115.38
4 784.62 23.0835.2939 % 76.92 707.70 107.70 92.30
5 707.70 20.5134.7822 % 79.49 628.21 128.21 71.79
6 628.21 17.9534.2854 % 82.05 546.16 146.16 53.84
7 546.16 15.3833.8024 % 84.62 461.54 161.54 38.46
8 461.54 12.8233.3332 % 87.18 374.36 174.36 25.64
9 374.36 10.2632.8766 % 89.74 284.62 184.62 15.38
10 284.62 7.6932.4319 % 92.31 192.31 192.31 7.69
11 192.31 5.1331.9996 % 94.87 97.44 197.44 2.56
12 97.44 2.5631.5776 % 97.44 0.00 200.000

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