Equal principal loan calculator
Equal-principal loan: each month repays P / n plus interest on the balance. 1,000,000 at 5% for 3 years: first 31,944.44, last 27,893.52.
Amortization schedule · 36 months
| Month | Payment | Principal | Interest | Balance |
|---|---|---|---|---|
| 1 | $31,944.44 | $27,777.78 | $4,166.67 | $972,222.22 |
| 2 | $31,828.70 | $27,777.78 | $4,050.93 | $944,444.44 |
| 3 | $31,712.96 | $27,777.78 | $3,935.19 | $916,666.67 |
| 4 | $31,597.22 | $27,777.78 | $3,819.44 | $888,888.89 |
| 5 | $31,481.48 | $27,777.78 | $3,703.70 | $861,111.11 |
| 6 | $31,365.74 | $27,777.78 | $3,587.96 | $833,333.33 |
| 7 | $31,250.00 | $27,777.78 | $3,472.22 | $805,555.56 |
| 8 | $31,134.26 | $27,777.78 | $3,356.48 | $777,777.78 |
| 9 | $31,018.52 | $27,777.78 | $3,240.74 | $750,000.00 |
| 10 | $30,902.78 | $27,777.78 | $3,125.00 | $722,222.22 |
| 11 | $30,787.04 | $27,777.78 | $3,009.26 | $694,444.44 |
| 12 | $30,671.30 | $27,777.78 | $2,893.52 | $666,666.67 |
| 13 | $30,555.56 | $27,777.78 | $2,777.78 | $638,888.89 |
| 14 | $30,439.81 | $27,777.78 | $2,662.04 | $611,111.11 |
| 15 | $30,324.07 | $27,777.78 | $2,546.30 | $583,333.33 |
| 16 | $30,208.33 | $27,777.78 | $2,430.56 | $555,555.56 |
| 17 | $30,092.59 | $27,777.78 | $2,314.81 | $527,777.78 |
| 18 | $29,976.85 | $27,777.78 | $2,199.07 | $500,000.00 |
| 19 | $29,861.11 | $27,777.78 | $2,083.33 | $472,222.22 |
| 20 | $29,745.37 | $27,777.78 | $1,967.59 | $444,444.44 |
| 21 | $29,629.63 | $27,777.78 | $1,851.85 | $416,666.67 |
| 22 | $29,513.89 | $27,777.78 | $1,736.11 | $388,888.89 |
| 23 | $29,398.15 | $27,777.78 | $1,620.37 | $361,111.11 |
| 24 | $29,282.41 | $27,777.78 | $1,504.63 | $333,333.33 |
| 25 | $29,166.67 | $27,777.78 | $1,388.89 | $305,555.56 |
| 26 | $29,050.93 | $27,777.78 | $1,273.15 | $277,777.78 |
| 27 | $28,935.19 | $27,777.78 | $1,157.41 | $250,000.00 |
| 28 | $28,819.44 | $27,777.78 | $1,041.67 | $222,222.22 |
| 29 | $28,703.70 | $27,777.78 | $925.93 | $194,444.44 |
| 30 | $28,587.96 | $27,777.78 | $810.19 | $166,666.67 |
| 31 | $28,472.22 | $27,777.78 | $694.44 | $138,888.89 |
| 32 | $28,356.48 | $27,777.78 | $578.70 | $111,111.11 |
| 33 | $28,240.74 | $27,777.78 | $462.96 | $83,333.33 |
| 34 | $28,125.00 | $27,777.78 | $347.22 | $55,555.56 |
| 35 | $28,009.26 | $27,777.78 | $231.48 | $27,777.78 |
| 36 | $27,893.52 | $27,777.78 | $115.74 | $0.00 |
Formula estimate only. Rates, taxes, and legal rules vary by jurisdiction.
What to know
Equal principal, called wongeum gyundeung in Korea, repays the same slice of principal every month: P / n. Interest is added on the remaining balance, so payment = P / n + balance x annual rate / 12, and the instalment shrinks steadily.
Worked example: 1,000,000 at 5 percent for 3 years repays 27,777.78 of principal each month. The first payment is 27,777.78 + 4,166.67 = 31,944.44, the last is 27,777.78 + 115.74 = 27,893.52, and the total interest is P x i x (n + 1) / 2 = 77,083.33.
Compared with equal payment on the same loan, which costs 78,952.30 in interest, you save 1,868.97, but the early cash burden is higher. On 300,000,000 at 4 percent for 30 years, the first payment is 1,833,333.33 against 1,432,245.89, while the interest total is 180,500,000 against 215,608,519.10.
The summary therefore lists both a First monthly payment and a Last monthly payment. Extra payments are supported and are added on top of the regular principal slice, with the interest and months saved reported against the plain schedule.
Because the balance falls by the same amount each month, the interest portion decreases linearly: for the 1,000,000 example it goes from 4,166.67 in month 1 to 115.74 in month 36, dropping by 115.74 every month.
Choose a specific task 1
Related tools 3
How to use Equal principal loan calculator
- Type the loan amount 1,000,000 and a rate of 5 percent.
- Set Years to 3.
- Read First monthly payment 31,944.44 and Last monthly payment 27,893.52.
- Check Total interest, which shows 77,083.33, and compare it with the equal-payment page.
Quick answers
Why is the first payment the highest?
The balance is at its largest, so the interest part is the biggest, and the fixed principal slice is added to it.
How much less interest than equal payment?
On 1,000,000 at 5 percent over 3 years, 1,868.97 less. The saving grows with the size and length of the loan.
Is there a closed formula for the total interest?
Yes: P x (annual rate / 12) x (n + 1) / 2. For 300,000,000 at 4 percent over 360 months that gives 180,500,000.