Equal Principal Loan Complete Guide

Mortgage repayment methods mainly fall into two types: equal principal and equal payment (annuity). Because equal principal results in lower total interest and faster principal repayment, many homebuyers see it as the "more cost-effective" choice. However, equal principal carries heavier monthly payments in the early period, so it is not suitable for everyone. This article comprehensively explains the equal principal repayment method across the definition, calculation formulas, monthly payment mechanics, comparison with equal payment (annuity), suitable audiences, and prepayment strategies, helping you make a more rational decision.

What Is Equal Principal

Equal principal is a mortgage repayment method in which a fixed amount of principal is repaid every month, plus the interest accrued on that month's remaining principal. Since the monthly principal repayment is fixed, the remaining principal decreases month by month, the monthly interest also decreases month by month, and therefore the total monthly payment decreases month by month.

Simply put, the equal principal monthly payment consists of two parts: a fixed "principal portion" plus a gradually declining "interest portion." Monthly payments are high in the early period and low in the later period, forming a downward curve that is "heavy at the front and light at the back."

Equal Principal Calculation Formula

The core calculation formula for equal principal is as follows:

• Monthly principal = total loan amount ÷ number of repayment periods (months)
• Monthly interest = remaining principal × monthly interest rate
• Monthly payment = monthly principal + monthly interest
• Total interest = (number of repayment periods + 1) × total loan amount × monthly interest rate ÷ 2

Here, the monthly interest rate = annual interest rate ÷ 12; the number of repayment periods = loan term in years × 12. For example, with a loan of ¥1 million, a 30-year term, and an annual rate of 4.0%, the monthly principal = 1,000,000 ÷ 360 ≈ 2,777.78 yuan, the first month's interest = 1,000,000 × (4.0% ÷ 12) ≈ 3,333.33 yuan, and the first month's payment = 2,777.78 + 3,333.33 = 6,111.11 yuan.

How Equal Principal Monthly Payments Are Calculated

To understand how equal principal monthly payments are calculated, the key is grasping the two core features: "fixed principal" and "decreasing interest." Let's break it down step by step.

1. Monthly Principal = Total Loan ÷ Number of Periods

The principal repaid each month is fixed, equal to the total loan amount divided by the total number of repayment months. This portion does not change over time and serves as the "steady anchor" of the monthly payment.

Example: with a loan of ¥1 million and a 30-year term (360 periods), the monthly principal = 1,000,000 ÷ 360 ≈ 2,777.78 yuan. Whether it is month 1 or month 360, the principal repaid each month is always 2,777.78 yuan.

2. Monthly Interest = Remaining Principal × Monthly Interest Rate

Monthly interest is calculated based on the remaining principal of that month. As principal is repaid each month, the remaining principal decreases month by month, so the interest also decreases month by month.

• Month 1: remaining principal 1,000,000 yuan, interest = 1,000,000 × (4.0% ÷ 12) ≈ 3,333.33 yuan
• Month 2: remaining principal 997,222.22 yuan, interest ≈ 3,324.07 yuan
• Month 360: remaining principal 2,777.78 yuan, interest ≈ 9.26 yuan

3. Monthly Payment = Monthly Principal + Monthly Interest (Decreases Monthly)

The monthly payment = fixed principal + that month's interest. Because the interest decreases month by month, the monthly payment also decreases month by month.

• Month 1: payment = 2,777.78 + 3,333.33 = 6,111.11 yuan
• Month 2: payment = 2,777.78 + 3,324.07 = 6,101.85 yuan
• Month 360: payment = 2,777.78 + 9.26 = 2,787.04 yuan

Equal Principal vs Equal Payment (Annuity): A Comparison

Equal principal and equal payment (annuity) are the two most common mortgage repayment methods. The core differences lie in whether the monthly payment is fixed, how much total interest is paid, and the repayment pressure in the early period.

1. Difference in Total Interest

Using a loan of ¥1 million with a 30-year term and an annual rate of 4.0% as an example:

• Equal principal total interest ≈ 601,666.67 yuan (about ¥602,000)
• Equal payment (annuity) total interest ≈ 716,121.96 yuan (about ¥716,000)
• Difference: equal principal saves about ¥114,000 in interest compared with equal payment (annuity)

The reason equal principal has lower total interest is that more principal is repaid each month, so the remaining principal declines faster and interest expense is reduced accordingly.

2. Monthly Payment Pressure Comparison

3. Comparison of Suitable Audiences

Who Is Equal Principal Suitable For

Equal principal is not suitable for everyone. The following 5 types of borrowers are better suited to the equal principal repayment method:

1. Borrowers with relatively high and stable current income: they can afford the higher early monthly payments without an overly high first month payment hurting their quality of life.
2. Older borrowers nearing retirement: equal principal payments decrease month by month, so as income drops after retirement the monthly payment also drops, matching post-retirement cash flow better.
3. People planning to hold the property long term (10+ years): with a long holding period, the total interest saved by equal principal is more substantial; the longer the time, the clearer the advantage.
4. Borrowers planning to make early repayments: equal principal repays more principal in the early period, so there is less remaining principal at prepayment time and more interest is saved.
5. Rational borrowers who want to reduce total interest expense: if paying less interest matters most to you, equal principal is the better choice.

Is Early Repayment Worth It with Equal Principal?

Whether early repayment is worthwhile depends on the repayment method, the remaining term, and the opportunity cost of funds. For equal principal, whether early repayment pays off needs to be discussed case by case.

1. Advantages of Early Repayment with Equal Principal

Equal principal repays more principal in the early period, so the remaining principal declines faster. If you make an early repayment within the first 1/3 of the term, you can save a considerable amount of later interest; the earlier you prepay, the more obvious the savings.

2. Disadvantages of Early Repayment with Equal Principal

In the later period of equal principal, the remaining principal is already very small and interest expense is very low. If more than half of the loan has been repaid, further early repayment saves limited interest, while using the funds for other investments may earn higher returns.

3. Early Repayment Decision Principles

• Early stage of the loan (within the first 1/3): early repayment is worthwhile and can greatly reduce later interest
• Middle stage of the loan (1/3 - 1/2): early repayment saves some interest, but you should compare it with investment returns
• Later stage of the loan (after 1/2): early repayment saves limited interest, and blind prepayment is not recommended
• Opportunity cost of funds: if investment returns are higher than the mortgage rate, early repayment is not recommended

How to Choose a Repayment Method

Choosing a repayment method requires comprehensive consideration of income, age, how long you will hold the property, the opportunity cost of funds, and other factors. Here is the decision checklist:

Decision Checklist

1. Assess your current monthly income: does the first month payment exceed 50% of your monthly income? If so, choose equal payment (annuity).
2. Judge your income trend: will your income rise or fall over the next 5 years? If it will fall, choose equal principal.
3. Determine how long you will hold the property: how long do you plan to keep the property? Over 10 years, choose equal principal; within 5 years, choose equal payment (annuity).
4. Assess the opportunity cost of funds: do you have an investment channel that beats the mortgage rate? If so, choose equal payment (annuity) to free up cash flow.
5. Consider your age: are you nearing retirement? If so, choose equal principal.
6. Estimate the total interest: does paying less interest matter most to you? If so, choose equal principal.

Common Questions (FAQ)

Q1: Why is the equal principal first month payment higher than equal payment (annuity)?

A: Equal principal repays a fixed amount of principal each month (total loan ÷ number of periods), and the first month's interest is calculated on the full principal, so the first month payment is the highest. Equal payment (annuity) repays only a small amount of principal in the first month, and the payment is spread over the whole term, so the first month payment is lower.

Q2: By how much does the equal principal monthly payment decrease each month?

A: The amount the monthly payment decreases each month = monthly principal × monthly interest rate. For example, with a loan of ¥1 million, 30 years, and 4.0%, the monthly principal is 2,777.78 yuan, the monthly interest rate is 0.333%, and the monthly payment decreases by about 9.26 yuan each month. Over 30 years, the accumulated decrease is about 3,333 yuan.

Q3: Can you switch from equal principal to equal payment (annuity) midway?

A: Most banks do not support switching the repayment method midway. It is recommended to decide on the repayment method before signing the contract. A few banks allow the repayment plan to be renegotiated when making an early repayment, but a separate application is required.

Q4: How are early repayment penalties calculated for equal principal?

A: Rules vary by bank. Some banks waive the penalty if the loan has been held for at least 1 year before an early repayment, while some banks charge 1%-3% of the prepaid amount. It is recommended to read the early repayment clauses in the loan contract carefully before signing.

Q5: Can the equal principal method be used for provident fund loans?

A: Yes. Provident fund loans also support both the equal principal and equal payment (annuity) methods. Since provident fund loan rates are lower (2.6% for a first home with a term over 5 years), the difference in total interest is relatively small, but it is still recommended to choose based on your own situation.

Q6: Is the equal principal total interest always lower than equal payment (annuity)?

A: Yes. With the same loan amount, term, and rate, the equal principal total interest is always lower than that of equal payment (annuity). This is because equal principal repays more principal in the early period, so the remaining principal declines faster and the accumulated interest is less.

Q7: Can equal principal and equal payment (annuity) be used in combination?

A: With a combined loan (provident fund + commercial), the provident fund portion and the commercial portion can each choose a different repayment method. However, a single loan cannot combine the two repayment methods internally.

Q8: Which repayment method is better under a floating LPR rate?

A: Under a floating LPR rate, rate changes affect the monthly payment and total interest. Equal principal is more sensitive to rate drops (the remaining principal declines quickly, making interest savings more obvious), so if you expect rates to fall in the future, equal principal has a bigger advantage.