How do I calculate a monthly loan payment?

Use the standard amortization formula PMT = r × P / (1 − (1 + r)^−n) where r is the monthly rate (APR/12), P is the principal, and n is the number of months.

What’s the difference between interest rate and APR?

The interest rate is the cost of borrowing the principal. APR includes the interest rate plus certain lender fees, expressed as a yearly rate.

Does paying extra each month reduce total interest?

Yes. Extra principal payments shorten the term and reduce the interest paid because future interest is calculated on a smaller balance.

Is biweekly payment faster than monthly?

Biweekly payments create 26 half-payments per year—roughly one extra monthly payment annually—typically shortening the payoff time.

Can I use this for car, personal, or student loans?

Yes, the same amortization math applies to any fixed-rate, fully-amortizing installment loan.

What happens if my payment doesn’t cover monthly interest?

Negative amortization can occur; the balance grows instead of shrinking. Increase the payment or shorten the term to avoid this.

Payment Calculator

Compute a monthly payment for a fixed term, or find how long a fixed monthly amount will take to pay off your balance. See totals, charts, and an amortization schedule.

Loan Amount

Loan Term (years)

Interest Rate (APR)

Monthly Payment

$1,687.71

Total of 180 Payments: $303,788.46

Total Interest: $103,788.46

Breakdown

Principal: 66%
Interest: 34%

Balance and costs over time

Amortization schedule(180 months) — click to expand

#	Interest	Principal	Ending Balance
1	$1,000.00	$687.71	$199,312.29
2	$996.56	$691.15	$198,621.13
3	$993.11	$694.61	$197,926.53
4	$989.63	$698.08	$197,228.45
5	$986.14	$701.57	$196,526.87
6	$982.63	$705.08	$195,821.79
7	$979.11	$708.60	$195,113.19
8	$975.57	$712.15	$194,401.04
9	$972.01	$715.71	$193,685.33
10	$968.43	$719.29	$192,966.05
11	$964.83	$722.88	$192,243.16
12	$961.22	$726.50	$191,516.67
13	$957.58	$730.13	$190,786.53
14	$953.93	$733.78	$190,052.75
15	$950.26	$737.45	$189,315.30
16	$946.58	$741.14	$188,574.17
17	$942.87	$744.84	$187,829.32
18	$939.15	$748.57	$187,080.76
19	$935.40	$752.31	$186,328.45
20	$931.64	$756.07	$185,572.38
21	$927.86	$759.85	$184,812.52
22	$924.06	$763.65	$184,048.87
23	$920.24	$767.47	$183,281.40
24	$916.41	$771.31	$182,510.10
25	$912.55	$775.16	$181,734.93
26	$908.67	$779.04	$180,955.89
27	$904.78	$782.93	$180,172.96
28	$900.86	$786.85	$179,386.11
29	$896.93	$790.78	$178,595.33
30	$892.98	$794.74	$177,800.59
31	$889.00	$798.71	$177,001.88
32	$885.01	$802.70	$176,199.18
33	$881.00	$806.72	$175,392.46
34	$876.96	$810.75	$174,581.71
35	$872.91	$814.81	$173,766.90
36	$868.83	$818.88	$172,948.02
37	$864.74	$822.97	$172,125.05
38	$860.63	$827.09	$171,297.96
39	$856.49	$831.22	$170,466.74
40	$852.33	$835.38	$169,631.36
41	$848.16	$839.56	$168,791.80
42	$843.96	$843.75	$167,948.05
43	$839.74	$847.97	$167,100.07
44	$835.50	$852.21	$166,247.86
45	$831.24	$856.47	$165,391.39
46	$826.96	$860.76	$164,530.63
47	$822.65	$865.06	$163,665.57
48	$818.33	$869.39	$162,796.18
49	$813.98	$873.73	$161,922.45
50	$809.61	$878.10	$161,044.35
51	$805.22	$882.49	$160,161.86
52	$800.81	$886.90	$159,274.95
53	$796.37	$891.34	$158,383.61
54	$791.92	$895.80	$157,487.82
55	$787.44	$900.27	$156,587.54
56	$782.94	$904.78	$155,682.77
57	$778.41	$909.30	$154,773.47
58	$773.87	$913.85	$153,859.62
59	$769.30	$918.42	$152,941.20
60	$764.71	$923.01	$152,018.20
61	$760.09	$927.62	$151,090.57
62	$755.45	$932.26	$150,158.31
63	$750.79	$936.92	$149,221.39
64	$746.11	$941.61	$148,279.78
65	$741.40	$946.31	$147,333.47
66	$736.67	$951.05	$146,382.42
67	$731.91	$955.80	$145,426.62
68	$727.13	$960.58	$144,466.04
69	$722.33	$965.38	$143,500.66
70	$717.50	$970.21	$142,530.45
71	$712.65	$975.06	$141,555.39
72	$707.78	$979.94	$140,575.45
73	$702.88	$984.84	$139,590.61
74	$697.95	$989.76	$138,600.85
75	$693.00	$994.71	$137,606.14
76	$688.03	$999.68	$136,606.46
77	$683.03	$1,004.68	$135,601.78
78	$678.01	$1,009.70	$134,592.07
79	$672.96	$1,014.75	$133,577.32
80	$667.89	$1,019.83	$132,557.49
81	$662.79	$1,024.93	$131,532.57
82	$657.66	$1,030.05	$130,502.52
83	$652.51	$1,035.20	$129,467.32
84	$647.34	$1,040.38	$128,426.94
85	$642.13	$1,045.58	$127,381.36
86	$636.91	$1,050.81	$126,330.55
87	$631.65	$1,056.06	$125,274.49
88	$626.37	$1,061.34	$124,213.15
89	$621.07	$1,066.65	$123,146.50
90	$615.73	$1,071.98	$122,074.52
91	$610.37	$1,077.34	$120,997.18
92	$604.99	$1,082.73	$119,914.45
93	$599.57	$1,088.14	$118,826.31
94	$594.13	$1,093.58	$117,732.73
95	$588.66	$1,099.05	$116,633.68
96	$583.17	$1,104.55	$115,529.13
97	$577.65	$1,110.07	$114,419.07
98	$572.10	$1,115.62	$113,303.45
99	$566.52	$1,121.20	$112,182.25
100	$560.91	$1,126.80	$111,055.45
101	$555.28	$1,132.44	$109,923.01
102	$549.62	$1,138.10	$108,784.91
103	$543.92	$1,143.79	$107,641.13
104	$538.21	$1,149.51	$106,491.62
105	$532.46	$1,155.26	$105,336.36
106	$526.68	$1,161.03	$104,175.33
107	$520.88	$1,166.84	$103,008.49
108	$515.04	$1,172.67	$101,835.82
109	$509.18	$1,178.53	$100,657.29
110	$503.29	$1,184.43	$99,472.86
111	$497.36	$1,190.35	$98,282.51
112	$491.41	$1,196.30	$97,086.21
113	$485.43	$1,202.28	$95,883.93
114	$479.42	$1,208.29	$94,675.63
115	$473.38	$1,214.34	$93,461.30
116	$467.31	$1,220.41	$92,240.89
117	$461.20	$1,226.51	$91,014.38
118	$455.07	$1,232.64	$89,781.74
119	$448.91	$1,238.80	$88,542.93
120	$442.71	$1,245.00	$87,297.94
121	$436.49	$1,251.22	$86,046.71
122	$430.23	$1,257.48	$84,789.23
123	$423.95	$1,263.77	$83,525.46
124	$417.63	$1,270.09	$82,255.38
125	$411.28	$1,276.44	$80,978.94
126	$404.89	$1,282.82	$79,696.12
127	$398.48	$1,289.23	$78,406.89
128	$392.03	$1,295.68	$77,111.21
129	$385.56	$1,302.16	$75,809.05
130	$379.05	$1,308.67	$74,500.38
131	$372.50	$1,315.21	$73,185.17
132	$365.93	$1,321.79	$71,863.38
133	$359.32	$1,328.40	$70,534.99
134	$352.67	$1,335.04	$69,199.95
135	$346.00	$1,341.71	$67,858.23
136	$339.29	$1,348.42	$66,509.81
137	$332.55	$1,355.16	$65,154.65
138	$325.77	$1,361.94	$63,792.71
139	$318.96	$1,368.75	$62,423.96
140	$312.12	$1,375.59	$61,048.36
141	$305.24	$1,382.47	$59,665.89
142	$298.33	$1,389.38	$58,276.51
143	$291.38	$1,396.33	$56,880.18
144	$284.40	$1,403.31	$55,476.86
145	$277.38	$1,410.33	$54,066.53
146	$270.33	$1,417.38	$52,649.15
147	$263.25	$1,424.47	$51,224.68
148	$256.12	$1,431.59	$49,793.09
149	$248.97	$1,438.75	$48,354.35
150	$241.77	$1,445.94	$46,908.40
151	$234.54	$1,453.17	$45,455.23
152	$227.28	$1,460.44	$43,994.80
153	$219.97	$1,467.74	$42,527.06
154	$212.64	$1,475.08	$41,051.98
155	$205.26	$1,482.45	$39,569.52
156	$197.85	$1,489.87	$38,079.66
157	$190.40	$1,497.32	$36,582.34
158	$182.91	$1,504.80	$35,077.54
159	$175.39	$1,512.33	$33,565.21
160	$167.83	$1,519.89	$32,045.33
161	$160.23	$1,527.49	$30,517.84
162	$152.59	$1,535.12	$28,982.72
163	$144.91	$1,542.80	$27,439.92
164	$137.20	$1,550.51	$25,889.40
165	$129.45	$1,558.27	$24,331.13
166	$121.66	$1,566.06	$22,765.08
167	$113.83	$1,573.89	$21,191.19
168	$105.96	$1,581.76	$19,609.43
169	$98.05	$1,589.67	$18,019.76
170	$90.10	$1,597.61	$16,422.15
171	$82.11	$1,605.60	$14,816.55
172	$74.08	$1,613.63	$13,202.92
173	$66.01	$1,621.70	$11,581.22
174	$57.91	$1,629.81	$9,951.41
175	$49.76	$1,637.96	$8,313.45
176	$41.57	$1,646.15	$6,667.31
177	$33.34	$1,654.38	$5,012.93
178	$25.06	$1,662.65	$3,350.28
179	$16.75	$1,670.96	$1,679.32
180	$8.40	$1,679.32	$0.00

What this Payment Calculator does

Loans look simple on the surface—borrow money today and pay it back over time—but the way interest compounds means small choices can change the total cost by thousands of dollars. This tool gives you two practical ways to plan: a fixed term mode that answers “How much will my payment be if I want to finish in N years?” and a fixed payment mode that answers “If I can afford a certain monthly amount, how long will payoff take?” Both modes produce the same details: the monthly amount involved, the number of payments, the total repaid, and the split between interest and principal. You also get a schedule that shows how each payment moves the balance.

How the math works

The monthly payment for a fully amortizing, fixed-rate loan comes from the standard annuity formula. The APR you enter is converted to a monthly rate by dividing by 12. Each month’s interest equals the current balance multiplied by that monthly rate; the remainder of the payment reduces principal. Because the balance shrinks over time, the interest portion gets smaller and more of each payment goes toward principal—the line chart and table make this pattern easy to see.

In the fixed payment tab, the calculator solves for the number of months instead of the payment. There’s a boundary condition: if the monthly amount is less than the interest accruing each month, the balance never falls. The calculator detects that case so you can adjust inputs.

Picking a term vs. picking a payment

Fixed term: target a finish date or lender-required term and find the payment that matches.
Fixed payment: start from a budgeted amount and learn how many months you’ll need.

Early payments and extra principal

Most installment loans allow extra principal payments without penalty. Even small extras have an outsized effect because they cut the balance early, reducing interest that would have accrued later. Rounding up your payment or adding a small monthly extra (e.g., $25–$100) is a simple habit with a big long-term impact.

Reading the schedule

The schedule lists every month with columns for interest, principal, and ending balance. The first months of a long loan are interest-heavy—that’s normal for amortization. As time passes, principal accelerates and the balance falls faster.

Rules of thumb

Shorter terms reduce total interest but require higher monthly payments. Pick a level that leaves room for emergencies.
Small APR improvements can save more interest than small term changes. Compare a few offers.
If you carry multiple debts, directing extra cash to the highest APR (avalanche) minimizes interest; the smallest-balance (snowball) approach maximizes momentum.

Estimates only. Lender policies and fees vary. Confirm terms with your lender before committing.