# Calculating Loan **URL:** \ **Category:** Factual Questions\ **Created:** [July 15, 2003, 3:26pm UTC](https://boards.straightdope.com/t/calculating-loan/188671 "2003-07-15T15:26:17Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![robz](https://avatars.discourse-cdn.com/v4/letter/r/ac8455/32.png) [@robz](https://boards.straightdope.com/u/robz)\ **Post date:** [July 15, 2003, 3:26pm UTC](https://boards.straightdope.com/t/calculating-loan/188671/1 "2003-07-15T15:26:17Z")
Hi I have a loan of $ 169,900, for 5 years. The monthly payments are $3,475.60. The first payment was on 11/28/2000. How do I calculate the interest rate, and the remaining principal balance. Thanks for any help you can give as you can see I am very math challenged. By theway, I called the lendor on this and they will provide the info for $100. Nice guys! Thanks Bob Z ---
**Author:** ![FatBaldGuy](https://avatars.discourse-cdn.com/v4/letter/f/ecd19e/32.png) [@FatBaldGuy](https://boards.straightdope.com/u/FatBaldGuy)\ **Post date:** [July 15, 2003, 3:41pm UTC](https://boards.straightdope.com/t/calculating-loan/188671/2 "2003-07-15T15:41:08Z")
Google on loan amortization. There are lots of sites out there where you can enter your payment information and they will calculate the interest rate and payment schedule for you. ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [July 15, 2003, 3:47pm UTC](https://boards.straightdope.com/t/calculating-loan/188671/3 "2003-07-15T15:47:44Z")
[http://cgi.money.cnn.com/tools/cutmortgage/cutmortgage.html](http://cgi.money.cnn.com/tools/cutmortgage/cutmortgage.html) ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [July 15, 2003, 3:56pm UTC](https://boards.straightdope.com/t/calculating-loan/188671/4 "2003-07-15T15:56:39Z")
Looks like an interest rate of 8.5! If you are wondering about a refinance, do it now! You would save save several hundred a month and over 20,000 dollars! ---
**Author:** ![sailor](https://avatars.discourse-cdn.com/v4/letter/s/a587f6/32.png) [@sailor](https://boards.straightdope.com/u/sailor)\ **Post date:** [July 15, 2003, 4:53pm UTC](https://boards.straightdope.com/t/calculating-loan/188671/5 "2003-07-15T16:53:53Z")
There is NO simple formula which will give you the interest rate given the other variables but it is quite simple to use a spreadsheet to find it by using succesive approximations. It is also extremely simple to make your own amortization sheet using any spreadsheet: ```auto Interest rate: 8.375832 Monthly payment: 3475.60 End of Interest Principal Principal Month # accrued amort. Owed 0 169900.00 1 1185.88 2289.72 167610.28 2 1169.90 2305.70 165304.57 3 1153.80 2321.80 162982.78 4 1137.60 2338.00 160644.77 5 1121.28 2354.32 158290.45 6 1104.85 2370.75 155919.70 7 1088.30 2387.30 153532.40 8 1071.63 2403.97 151128.43 9 1054.86 2420.74 148707.69 10 1037.96 2437.64 146270.04 11 1020.94 2454.66 143815.39 12 1003.81 2471.79 141343.60 13 986.56 2489.04 138854.56 14 969.19 2506.41 136348.14 15 951.69 2523.91 133824.23 16 934.07 2541.53 131282.71 17 916.33 2559.27 128723.44 18 898.47 2577.13 126146.32 19 880.48 2595.12 123551.20 20 862.37 2613.23 120937.97 21 844.13 2631.47 118306.50 22 825.76 2649.84 115656.66 23 807.27 2668.33 112988.33 24 788.64 2686.96 110301.37 25 769.89 2705.71 107595.66 26 751.00 2724.60 104871.06 27 731.99 2743.61 102127.45 28 712.84 2762.76 99364.68 29 693.55 2782.05 96582.63 30 674.13 2801.47 93781.17 31 654.58 2821.02 90960.15 32 634.89 2840.71 88119.44 33 615.06 2860.54 85258.90 34 595.10 2880.50 82378.39 35 574.99 2900.61 79477.78 36 554.74 2920.86 76556.93 37 534.36 2941.24 73615.68 38 513.83 2961.77 70653.91 39 493.15 2982.45 67671.46 40 472.34 3003.26 64668.20 41 451.37 3024.23 61643.98 42 430.27 3045.33 58598.64 43 409.01 3066.59 55532.05 44 387.61 3087.99 52444.06 45 366.05 3109.55 49334.51 46 344.35 3131.25 46203.26 47 322.49 3153.11 43050.15 48 300.48 3175.12 39875.04 49 278.32 3197.28 36677.76 50 256.01 3219.59 33458.16 51 233.53 3242.07 30216.10 52 210.90 3264.70 26951.40 53 188.12 3287.48 23663.92 54 165.17 3310.43 20353.49 55 142.06 3333.54 17019.95 56 118.80 3356.80 13663.15 57 95.37 3380.23 10282.92 58 71.77 3403.83 6879.09 59 48.02 3427.58 3451.51 60 24.09 3451.51 0.00 = = = = = = = = = = = = = = Totals: 38636.00 169900.00 ``` 8.36% might not be a bad rate. It depends on the other factors of the loan.