A mortgage payment factor tells you the periodic principal-and-interest payment per stated amount borrowed. Read the factor’s units before multiplying. A decimal in one practice question is not a universal number for every loan.
Jump to: Payment factors · Total interest over the loan term · Payment practice
| How the monthly factor is stated | Calculation |
|---|---|
| Per $1 borrowed | Loan amount × factor |
| Per $1,000 borrowed | (Loan amount ÷ 1,000) × factor |
Why the factor changes
For a fully amortizing fixed-rate mortgage, the payment calculation depends on the loan amount, interest rate, and repayment term. A table or supplied factor packages that calculation for a particular rate, term, and payment frequency. Use the factor supplied in the exercise, or the correct row and column of its table. See the CFPB explanation of monthly mortgage payments.
Worked example: two ways to state the same factor
An original practice exercise supplies a loan amount of $240,000 and a monthly payment factor of 0.006 per dollar borrowed.
$240,000 × 0.006 = $1,440 monthly principal and interest.
If the same factor is stated as $6 per $1,000 borrowed, calculate ($240,000 ÷ 1,000) × $6 = 240 × $6 = $1,440. Multiplying $240,000 directly by 6 would make the answer 1,000 times too large.
Principal and interest is not the entire housing expense
If this example separately gives annual property taxes of $3,600 and annual property insurance of $1,200, the monthly amounts are $300 and $100. PITI is $1,440 + $300 + $100 = $1,840.
Mortgage insurance and association dues may also affect total housing expense. Add each item only once and follow what the question asks for. See Mortgage Qualification: HER vs. TOR and PITI.
Do I need to memorize the factor?
Focus on using a supplied factor correctly. Do not memorize one decimal and reuse it for a different loan. If a practice problem requires a table and you cannot find it, send support the full permitted practice problem and its table or instructions.
A payment factor is also different from an annual interest rate. Loan balance × annual rate ÷ 12 gives a monthly interest calculation under that simplified convention; it does not calculate a fully amortizing principal-and-interest payment.
How do I calculate total interest over the life of a loan?
Total scheduled interest = all scheduled principal-and-interest payments − original loan principal. When the exercise gives equal monthly payments for a fully repaid loan, multiply the monthly P&I payment by the number of months, then subtract the amount borrowed.
Assumptions: The loan is fully repaid by the stated equal payments, with no extra principal payments, refinancing, payment changes, balloon balance, or separate financing charges. Use the payment amount supplied in the exercise.
- Count payments: years × 12 for monthly payments.
- Add scheduled P&I: monthly P&I × number of payments.
- Remove principal: subtract the original amount borrowed to find interest.
Worked example: total paid and total interest
An original exercise supplies a $200,000 loan repaid with 180 monthly P&I payments of $1,600. Assume those payments exactly repay it.
| Requested amount | Calculation | Result |
|---|---|---|
| Total scheduled P&I | $1,600 × 180 | $288,000 |
| Total principal repaid | Original loan amount | $200,000 |
| Total scheduled interest | $288,000 − $200,000 | $88,000 |
If monthly escrow adds $400 for taxes and insurance, use $1,600 for this interest calculation, not the $2,000 total housing payment. Taxes, insurance, and association charges are not loan interest.
Do not multiply the original balance by the annual rate and the full term for an amortizing loan: the principal balance falls as payments are made. If the question already supplies P&I, you do not need to derive it again from the interest rate.
What changes the shortcut?
A balloon loan needs its final balance included in the repayment schedule. Extra payments, adjustable payments, refinancing, and a rounded final installment can change actual interest. Use the actual schedule when those facts appear. This exercise calculates scheduled interest; a lender's disclosed finance charge, APR, or total loan cost can include additional amounts.
Reference: CFPB's explanation of mortgage payments and amortization. Expansion checked October 21, 2026.
Practice total-interest calculations
- A $120,000 loan is fully repaid by 120 equal monthly P&I payments of $1,400. Find total P&I and total interest.
- A $180,000 loan is fully repaid by 180 equal monthly P&I payments of $1,500. The monthly payment also includes $350 of escrow. Find total interest using the stated assumptions.
Answers: (1) $168,000 total P&I; $48,000 interest. (2) $1,500 × 180 − $180,000 = $90,000 interest. Exclude the $350 escrow.
Try three practice questions
- A question gives a $180,000 loan and a monthly factor of $6.50 per $1,000. What is monthly principal and interest?
- A $200,000 loan uses a supplied monthly factor of 0.0055 per dollar. What is monthly principal and interest?
- Monthly principal and interest is $1,100. Annual property taxes are $2,400 and annual property insurance is $1,200. What is PITI?
Answers and explanations
- $1,170. 180 × $6.50.
- $1,100. $200,000 × 0.0055.
- $1,400. $1,100 + $200 + $100. These exercises use supplied hypothetical factors.
Keep studying
Review how to choose a math formula. Return to the exam-prep guide.
Submit a support request with your course, lesson or practice-question number, and the step you want explained. These are original study exercises, not recalled state-exam questions.
Comments
0 comments
Article is closed for comments.