Finance July 31, 2025

Quick Basic Math Calculations

Listed below are a few formula calculations to help with some basic real estate related math.

Loan-to-Value Ratio (LTV) Calculation

This ratio is a key measure that lenders use to assess the risk of a loan. The ratio measures the relationship between the “amount borrowed” and the “property’s appraised value”. It’s a key factor that lenders use to assess the risk of a loan. A lower LTV ratio is favorable because it implies that there is “more equity in the property” and thus typically results in more favorable loan terms, i.e.,  lower interest rates, avoidance of private mortgage insurance (PMI), etc. This is important to have before starting the home search because the LTV helps buyers determine how much they can borrow and at the same time gives insight to sellers about potential financing challengesthat the buyers might face.

Formula: (Appraised Property Value / Mortgage Amount) × 100 = LTV

Example:

  • Home purchase price $500,000.
  • Buyer has $75,000 available for down payment; Mortgage amount to borrow: 500,000-75,000 = $425,000
  • LTV ratio to borrow: ($425,000 / $500,000) × 100 = 85%

A LTV of 80% is typically the highest ratio many lenders will allow without requiring PMI, saving the borrower on additional insurance costs. In this example of 85% it is less than 80% so it gives insight on how the buyer is approximately structuring their financing in purchasing this property.

Percentage Calculation

To help calculate financial projections and decisions for commission rates, return on investments, etc.,

Formula: (Price × Fee percent)

Example :

If your real estate agent takes 5% commission on a propertyselling price of $1,000,000 then the commission fee is calculated as follows:
$1,000,000 x 5% (or .05 in decimal form) = $50,000

  • Whole (the sale price) = $1,000,000
  • Percentage of Commission = 5%
  • Commission fee) = x = $50,000

Simple Interest Calculation

It is calculated for interest earned or paid on a principal amount over a specific period at a fixed interest rate. Simple interest is not compound interest in that interest is not added to the principal at each interest period, thus the interest earned does not increase over time. The purpose of this formula is to show borrowers and/or investors what the cost or earnings from a simple financial transaction (no complexities of compounding)is. It helps provide clarity on the financial decision.

Formula: P (Principal Amount) × IR (Rate of Interest) × T (Time) = IInterest

Example:

For a $1,000 loan at a 6% annual interest rate over five years.
$1,000 × 0.06 × 5 = $150

Principal Amount = $1,000
Rate of Interest = 6% or (0.06 in decimal form)
Time = 5 years
Interest = $300

The calculation shows an interest accrued over five years on a $1,000 loan at a 6% interest rate is $300.

Down Payment Calculation

In order to calculate the initial payment needed to purchase a home, the down payment equation is used. Typically this amount is a percentage of the total sale price, and it reduces the loan amount needed by this calculated amount which in turn affects the borrower’s mortgage payments and interest over time.

Formula: Sale Price × Percentage Payment = Down Payment Amount

Example:

In order to qualify for financing a new home purchase of $800,000, if client puts at least 20% down,

the downpayment calculation = $800,000 × 20% (or 0.20 in decimal form) = $160,000

Thus the downpayment is $160,000 on a $800,000 house which impacts the buyer’s mortgage requirements, but lowers the loan amount to $640,000 ($800,000-$160,000) and potentially qualifies the buyer for better interest rates.

Closing Costs Calculation

In order to best prepare for the financial transaction it is important to plan and understand for closing costs which typically include: appraisal, title insurance, legal, and prepaid items.

Formula: Purchase Price × % of Closing Costs = Closing Costs

Example:

The closing costs typically range from 2% to 5% of the home’s purchase price.

If purchase price is $800,000 and closing costs percentage is 5 % of the purchase price
$800,000 × 4% = $32,000

The buyer should be prepared to budget and come up with approximately $32,000 in closing costs in addition to the home’s purchase price.

Price per Square Foot (ppSft) Calculation

Ppsqft is used to assess a property’s value by breaking down its price in relation to its size. This metric used for property value comparison to get at competitive pricing and provide a solid basis for negotiation.

Formula: Sale Price of the Property / Total Square Footage = Price per Square Foot

Example:

House sold price of $800,000 and has 2,500 square feet of living space.
$800,000 / 2,500 sq ft = $320 price per sq ft

This calculation is indicative the property costs $320 for every square foot of space. It helps make it easy to compar itse value with other homes in the areas based on their sizes and sale prices.

Affordability Calculation

This calculation is used to determine and estimate the maximum mortgage amount that the buyer can spend for buying a home. It typically takes into account the buyer’s income, debt, and current interest rates.

Formula: (Gross Monthly Income × Affordability Ratio) – Total Monthly Debt Payments
= Maximum Affordable Mortgage

Example: At a gross monthly income of $6,000, with monthly debt payments of $1,000, and the lender’s qualifying ratio suggests that housing expenses should not exceed 28% or .28 in decimal form (affordability ratio) of the monthly income.
($7,000 × 28%) – $1,000 = $960

This $960 is the number used to figure what the buyer can focus on purchasing a property for within an appropriate price range.

Cash Flow Calculation

Investors use this formula to help them determine the “net income” generated from an” investment property” after all operating expenses and mortgage payments have been deducted. The goal of this metric is to assess whether a property will provide a positive income stream and justify their investment. A positive cash flow is indicative that a property will generate more income than the  cost to maintain and operate it and a negative cash flow is indicative that the investmentmost likely may not be financially viable in its current state.

Formula: Monthly Rental Income – Monthly Expenses = Monthly Cash Flow

Example:

When considering a property that generates $5,000 in monthly rental income. The property’s monthly expenses, including mortgage, insurance, taxes, and maintenance, total $4,000.
$5,000 monthly rental income – $4,000 monthly expenses = $1,000 monthly cash flow – Positive flow – indicating a profitable investment opportunity.

Return On Investment (ROI) Calculation

It is a critical metric for Investors that helps them measure and calculate the percentage return on an investment relative to its cost, when evaluating the profitability of real estate transaction. ROI  helps understand the gain or loss generated (or potential) on a property compared to the initial investment: inclusive of all costs, purchase price, renovation expenses, and selling costs.

Formula: (Net Profit / Total Investment Cost) × 100 = ROI OR [(Selling Price – Total Investment Cost) / Total Investment Cost] × 100 = ROI
Both of the above equations are the same since Net Profit = Selling Price – Total Investment

Example:

Purchase Price $300,000, Rennovation costs $20,000
Total Investment Cost = $320,000 ($300,000 + $20,000)

Selling Price = $450,000

[($320,000 – $450,000) / $450,000] × 100 = 29%

ROI = 29%
This ROI signifies a profitable and effective use of the investor’s capital utilization.

Net Operating Income (NOI) Calculation

NOI helps assess a property’s profitability and potential cash flow and measures the “annual income” generated by a property after “operating expenses” have been subtracted but before “deducting taxes and financing costs”.

Formula: Gross Rental Income – Operating Expenses = NOI

Example:

Rental property generates annual rental income of $90,000.

Annual operating expenses (maintenance, insurance, property management fees, etc.) are $30,000.

NOI =$90,000 – $30,000 = $60,000

A positive NOI of $60,000 is significant and it means that this property is generating sufficient income to cover operating expenses – key factor for long-term investment sustainability. This metric results is signifiing a strong income-producing capability (before financing or taxes).

Capitalization Rate (cap rate) Calculation

The cap rate, is used to estimate the potential return on an income-producing property, independent of financing. This metric provides a snapshot of the property’s operational performance and is derived by comparing the NOI to its current market value. This ratio is used when evaluating the ROI for different properties and helps facilitate comparisons across the market.

Formula: (NOI / Current Market Value) × 100 = Cap Rate

Example:

Current Market Value = $750,000. NOI is $15,000

cap rate = ($80,000 / $750,000) × 100 = 10.7%

A cap rate of 10.7% indicates a potentially attractive investment opportunity, assuming it aligns with the investor’s risk tolerance and investment criteria.

Break-even Ratio (BER) Calculation

This BER metric calculation helps assess investment properties’ financial stability and risk, as well as helps to understand the minimum occupancy rate needed to ensure that a rental property’s income covers its operating expenses.

Formula: (Total Operating Expenses / Gross Potential Income) × 100 = BER

Example:

Property price $1,000,000, renovations $200,000, annual gross potential rental income $150,000, fully occupied, with annual operating expenses$80,000.
BER = ($80,000 / $150,000) × 100 = 53.3%

53% occupancy rate is needed to cover the operating expenses, it also demonstrates the level of financial risk and the occupancy threshold that is required to avoid losses on the investment.

 

Debt Service Coverage Ratio (DSCR) Calculation

DSCR ratio evaluates the risk of lending to or investing in a property. It measures a property’s ability to cover its debt payments with its income. A DSCR greater than one is desired and indicates that the property is generating enough income to cover its debt obligations, reducing the risk of default. Lenders typically look for a DSCR above a certain threshold to ensure an adequate cushion to absorb any unforeseen declines in income.

Formula: NOI / Total Debt Service = DSCR

Example:

$50,000 NOI on a rental property with annual mortgage payments of $35,000.
$50,000 / $35,000 = 1.43

NOI = $50,000
Total Debt Service = $35,000
DSCR = 1.43

A DSCR of 1.43 means that the property generates 43% more income than needed to cover the debt service, which indicates that it is a good financial health and a low risk of default.

After Repair Value (ARV) Calculation

The ARV is a key projection concept and metric in real estate investing for those involved in house flipping or property renovation. It focuses on the estimated value of a property’s value after it has been improved or renovated -after all repairs, renovations, or improvements have been completed. This metric allows buyers or investors engaged in flipping or rehabbing properties to estimate the future selling price and potential profit. Understanding how to calculate and accurately estimate ARV allows to make informed decisions about the feasibility and profitability of a renovation project, ensuring that the costs of repairs do not exceed the value added.

So why does ARV Matter? It helps with:
Investment Decisions: Helps investors determine if a property is worth buying and fixing.
Loan Calculations: Lenders often use ARV to decide how much money to lend for rehab projects.
Profit Estimation: ARV is used to calculate potential profit margins.

How to Calculate ARV?

Formula: ARV =Property’s Purchase Price + Value of Renovations = ARV

First, find Comparable Properties (Comps) at recently sold homes in the same area to determine the purchase price
Ensure they are similar in size, style, and condition to the expected post-renovation state.

Then, get the Average the Sale Prices of Comps. To do that use 3–5 best comparable properties because the average gives a solid estimate of the ARV.
Example:
If similar renovated homes in the area sell for:

$450,000
$460,000
$440,000
Then the ARV for purchase price would be:

ARV for rennovated selling price=(450,000+460,000+440,000)/3=$450,000

Calculation

Property’s Purchase Price should be below selling price

If purchased for $400,000, Rennovations Value = $50,000
Selling Price should exceed this ARV of $450,000 amount to make profit since after the necessary repairs and improvements of $50,000, and based on a comparative market analysis, the expected selling price should be >$450,000 but may not be. Since the market analysis predicts a selling price of $450,000, the project at 450,000 is not profitable but if sells for $500,000 it could result in a substantial profit. Thus, these calculations and metrics are essential for assessing properties and providing a framework for it. Based on the above scenario the investor should target less than $40o,000 for a purchase price to make profit. After Repair Value (ARV) is key in calculating value.