Where to Find Every Number for Your Rental Property Analysis
Rent, vacancy, running costs, loan, closing costs and growth: where to find each real number, what our defaults assume and why.
By Real-Estate Analyzer Team · Updated
The analyzer only needs three numbers from you: the price, the monthly rent and the interest rate. Everything else starts with a typical value, clearly marked as a default, so you get a useful answer straight away. This guide shows where to find the real number for each default, so you can replace it when you know better.
Our defaults are typical as of October 2026. They are rules of thumb, not predictions, and they are deliberately on the cautious side. Your lender, your local market and your own property will beat them every time.
Monthly rent
What it is: the rent you can realistically charge each month for this property, not the best month you can imagine.
Where to find it: look at listings for similar homes nearby (same size, condition and area) and note what they ask, and how long they have been listed. A local letting or property management agent will often give a rental valuation for free. If the property is already let, ask for the signed lease and the rent history.
Our default: none. Rent is one of the three numbers you must enter, because every other result depends on it.
Rule of thumb: use what a comparable home actually rents for, and be suspicious of rent that is well above its neighbours. Rent set too high is the most common cause of long empty periods. The 1% rule is a quick filter, not a way to estimate rent.
Vacancy (empty months)
What it is: the months a year the property earns no rent, between tenants or because a tenant does not pay.
Where to find it: the property's own history is best: ask the seller for the rent roll or lease start dates for the last two years. Otherwise ask a local agent how long a home like yours takes to let, and check how long comparable listings stay up. Official statistics offices in many countries publish rental vacancy rates for regions, which show the general direction but not your street.
Our default: 1 empty month a year (about 8% of rent). It assumes one change of tenant a year with a few weeks to re-let and prepare the home. We do not use zero, because tenants move.
Rule of thumb: 5% to 8% suits many markets. Go higher for older buildings, slow areas or short tenancies, and lower only if the history proves it. Read how vacancy affects returns.
Running costs and management
What it is: everything you pay to keep the property let: property tax, insurance, repairs, big replacements (roof, boiler, appliances) and, if you hire one, a management or letting agent.
Where to find it: your property tax bill (or council tax and ground rent where they apply), an insurance quote, the seller's last two years of expenses, and a written fee schedule from a local management agent. Service charges or homeowners' association fees are on the listing or in the sale documents.
Our default: 27% of rent for tax, insurance, repairs and big replacements, plus 8% of rent for management. That is 35% of rent in total, the low end of the usual 35% to 50% band. It is a starting point, not a quote.
Rule of thumb: older homes, high-tax areas and condos with fees sit higher in that band. See how to estimate your running costs for a line-by-line method.
The loan: rate, down payment and term
What it is: how much of your own cash goes in, how much you borrow, what you pay for it, and how long you take to repay it.
Where to find it: a written quote from a lender or mortgage broker for an investment loan, not a headline rate for owner-occupiers. Ask for the rate, the maximum loan to value, the term and the fees. Rates change with the market, so a quote is only good for a limited time.
Our defaults: 25% down payment, a 25-year repayment loan. We do not default the interest rate, because it moves with the market and a wrong guess would quietly distort every result. Use your lender's quote.
Rule of thumb: many lenders ask investors for 20% to 25% down. A shorter term raises the payment but pays the loan off sooner. If you plan an interest-only loan, read repayment vs interest-only and how the mortgage affects returns.
Closing costs
What it is: the one-off costs of buying, on top of the price: taxes or stamp duty, legal and notary fees, survey and valuation, loan arrangement fees and agent fees where you pay them.
Where to find it: your lender's fee estimate, a quote from your solicitor, conveyancer, notary or closing agent, and your local transfer tax rules. Many jurisdictions charge investors more transfer tax than owner-occupiers, so check the investor rate.
Our default: 3% of the price, the low-to-middle part of the typical 2% to 5% range.
Rule of thumb: in some countries transfer taxes alone can exceed 5%, so treat 3% as a placeholder until you have real quotes. Closing costs count as cash you put in, so they lower your return on that cash.
Growth and how long you hold
What it is: how fast the property value and the rent rise each year, and how many years you plan to own before you sell.
Where to find it: a national or regional house price index and rental index from your statistics office or a major lender show past growth. Past growth is a guide, not a promise. Your own plan sets the hold period.
Our defaults: 2% a year for both value and rent, held for 10 years. That is roughly in line with long-run inflation, which is a cautious assumption.
Rule of thumb: do not let a deal depend on fast growth. If it only works at 4% or more a year, it is a bet on the market. Check it at 0% growth too, which the analyzer shows. See IRR explained for how hold period and growth shape the long-term return.
Key Takeaways
- 1You must enter three numbers: price, rent and interest rate. Everything else has a typical default you can replace.
- 2Our defaults: 25% down, 3% closing costs, 25-year loan, 1 empty month a year, running costs of 27% of rent plus 8% management, 2% growth, 10-year hold.
- 3Defaults are rules of thumb, typical as of October 2026, and deliberately cautious. A real quote or a real bill always beats them.
- 4Best sources: comparable listings and a local agent for rent, your lender's written quote for the loan, your tax bill and insurance quote for costs.
- 5Do not let a deal rely on fast growth or on zero empty months.
- 6Start with the defaults, then replace the ones that move the result most, usually rent, running costs and rate.
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A small team of investors. Every worked example in our guides is calculated with the same engine the analyzer runs. How we check our numbers. Educational content, not tax, legal, or investment advice.