function calculateFlip() {
// 1. Get Input Values
var purchasePrice = parseFloat(document.getElementById('purchasePrice').value) || 0;
var repairCosts = parseFloat(document.getElementById('repairCosts').value) || 0;
var arv = parseFloat(document.getElementById('arv').value) || 0;
var holdingTime = parseFloat(document.getElementById('holdingTime').value) || 0;
var interestRate = parseFloat(document.getElementById('interestRate').value) || 0;
var closingCosts = parseFloat(document.getElementById('closingCosts').value) || 0;
// Validation
if (purchasePrice === 0 || arv === 0) {
alert("Please enter at least a Purchase Price and an After Repair Value (ARV).");
return;
}
// 2. Perform Calculations
// Calculate Loan Interest (Assuming loan amount is Purchase Price + Repairs, typical hard money structure)
// Simplified: Interest is calculated on the Purchase Price for this generic example unless specified otherwise.
var loanAmount = purchasePrice;
var monthlyInterest = (loanAmount * (interestRate / 100)) / 12;
var totalHoldingCosts = monthlyInterest * holdingTime;
// Total Invested Cash (Cost Basis)
var totalCostBasis = purchasePrice + repairCosts + closingCosts + totalHoldingCosts;
// Net Profit
var netProfit = arv – totalCostBasis;
// ROI Calculation
// ROI = (Net Profit / Total Cost Basis) * 100
var roi = 0;
if (totalCostBasis > 0) {
roi = (netProfit / totalCostBasis) * 100;
}
// 3. Update DOM
var profitEl = document.getElementById('resNetProfit');
var roiEl = document.getElementById('resROI');
var costEl = document.getElementById('resTotalCost');
var resultsDiv = document.getElementById('resultsSection');
// Formatting
profitEl.innerHTML = "$" + netProfit.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 0});
roiEl.innerHTML = roi.toFixed(2) + "%";
costEl.innerHTML = "$" + totalCostBasis.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 0});
// Color coding for profit
if (netProfit < 0) {
profitEl.style.color = "#e53e3e"; // Red
} else {
profitEl.style.color = "#27ae60"; // Green
}
// Show results
resultsDiv.classList.add('active');
}
How to Calculate House Flipping Profit
Real estate investing, specifically house flipping, relies heavily on accurate math. Before you purchase a property, you must determine if the potential profit margin justifies the risk. This House Flipping Profit & ROI Calculator helps investors analyze deals by factoring in the "hidden" costs that often erode profits, such as holding times and loan interest.
Pro Tip: The 70% Rule
Many experienced flippers use the 70% rule as a quick filter. It states that you should pay no more than 70% of the After Repair Value (ARV) minus the repair costs. Formula: (ARV x 0.70) – Repairs = Max Purchase Price.
Understanding the Input Metrics
Purchase Price: The amount you pay to acquire the property.
Repair/Rehab Costs: The total budget for materials and labor to renovate the property. Always add a 10-15% contingency buffer here for unexpected issues.
After Repair Value (ARV): The estimated market value of the home once all renovations are complete. This should be based on comparable sales (comps) in the neighborhood.
Holding Costs (Project Duration): Time is money. The longer you own the house, the more you pay in property taxes, insurance, utilities, and loan interest.
Closing Costs: Don't forget agent commissions (usually 5-6% of the selling price) and title fees when you buy and sell.
What is a Good ROI for Flipping Houses?
Return on Investment (ROI) measures the efficiency of your investment. While every investor has different goals, a common benchmark for house flipping is a minimum ROI of 15% to 20%. However, due to the high risks involved (market fluctuations, construction delays), many investors aim for an ROI closer to 30% to ensure a safety net.
Common Mistakes That Kill Profitability
The most common reason house flips fail is not the market—it's underestimating costs. New investors often ignore holding costs (interest payments during the renovation) or overestimate the ARV. Using a detailed calculator like the one above ensures you account for interest rates and project duration, giving you a realistic picture of your net profit.