How to Analyze a Rental Property: 5 Numbers (Quebec)

You've spotted a plex for sale on Centris or DuProprio and you're wondering whether it's a good buy. To analyze a rental property in Quebec (a plex in particular), check five numbers: the price, the real gross income (the rents written into the leases, not the "potential" the listing advertises), the operating expenses, the net operating income (NOI) and the cash flow. In two minutes, these numbers tell you whether the building pays for itself. Never take the seller's advertised income and expenses at face value: they're almost always optimistic. The fastest way to run the numbers without errors is to import the listing into a calculator that returns the NOI, cash flow, GRM and cap rate in one shot. This guide gives you the method, with a worked Quebec example for 2026.

Key takeaways

• Five numbers are enough for a first pass: the price, the real gross income, the expenses, the NOI and the cash flow.
• NOI = real gross income − operating expenses (excluding the mortgage); cash flow = NOI − mortgage payment.
• Two quick filters in Quebec: the GRM (price ÷ gross income; aim under 15, Montreal often runs 18–22) and the cap rate (NOI ÷ price; 3.5–4.5% in Montreal in 2026).
• A good cash flow in Montreal = $100 to $200 per unit per month; a single vacant unit can push it into the red.
• The American "1% rule" doesn't apply here (median plex price in Montreal above $865,000); import the listing instead of retyping it into a spreadsheet.

---

The 5 numbers to check on a plex listing

A Centris or DuProprio listing almost always gives the asking price, the "potential" gross income, the number of units, the taxes (municipal and school) and the municipal assessment. It rarely gives the real rent on each lease, the energy paid by the owner, vacancy, and management. So to analyze an income property, rebuild five numbers:

1. The asking price: the starting point, to compare against recent sales.
2. The real gross income: the rents written into the current leases, not the listing's "potential."
3. The operating expenses: taxes, insurance, energy, maintenance and management.
4. The net operating income (NOI): the real income minus the expenses, before the mortgage.
5. The cash flow: the NOI minus the mortgage payment.

The line items the listing leaves out are exactly the ones that tip a "nice" plex into the red.

Action point: write down the five numbers; any figure missing from the listing becomes a question for the seller.

---

Advertised vs. real income and expenses

Listings often show potential gross income: market-rate rents and minimized expenses. Your job is to normalize everything against the real numbers.

For income, start from the current leases and the seller's declaration, not the "potential." In Quebec, rent increases are regulated: the Tribunal administratif du logement (TAL), Quebec's rental board, publishes its rent-setting guidelines every year, so a "market" rent isn't always enforceable on the tenant in place.

For expenses, add the line items the seller forgets:

• the taxes (municipal and school tax bills);
• the insurance;
• the energy, if the owner pays it;
• the maintenance, by setting aside 1 to 2% of the building's value per year;
• the management, about 5% of rents, even if you self-manage;
• a vacancy allowance, even if the listing shows 0%.

On the legal side, demand the seller's declaration. The OACIQ (the body that regulates real estate brokerage in Quebec) notes that many plexes sell without legal warranty, which shifts the latent-defect risk onto the buyer.

Action point: rebuild income and expenses yourself; never take the seller's table as is. For the physical and legal traps, see our red flags before you buy.

---

Calculate NOI and cash flow in 2 minutes (worked 2026 example)

NOI = real gross income − operating expenses (excluding the mortgage). Cash flow = NOI − mortgage payment. Cash flow is what decides whether the building pays for itself.

Take a Quebec example from 2026: a triplex at $975,000, rented for $4,000 a month, or $48,000 a year. Here are its operating expenses, line by line:

Item	Monthly amount
Taxes (municipal + school)	$420
Insurance	$180
Maintenance	$200
Snow removal	$75
Total	$875

Over the year, that's $875 × 12 = $10,500 in operating expenses. That gives the NOI:

NOI = $48,000 − $10,500 = $37,500 per year.

The mortgage costs $2,450 a month (about 4.5% over 25 years), or $29,400 a year. The cash flow follows directly:

Cash flow = $37,500 − $29,400 = $8,100 per year = $675 a month = $225 per unit.

Verdict: positive. The building pays for itself and passes the first filter. This example is deliberately simplified: a careful analysis also adds a vacancy, management and reserve allowance (see the previous section), which lowers the NOI. For the payment, use the mortgage calculator; for the whole picture, the rental yield calculator returns the NOI and cash flow automatically.

Action point: calculate the cash flow per unit; below $0, walk away or renegotiate the price.

---

The quick ratios: GRM and cap rate (not the "1% rule")

Two ratios are enough to sort a plex in seconds: the GRM (gross rent multiplier) and the cap rate (capitalization rate).

• GRM = price ÷ annual gross income. The lower, the better.
• Cap rate = NOI ÷ price. The higher, the better.

Here are indicative benchmarks for Quebec in 2026:

Market	GRM (quick filter)	Cap rate 2026	Target cash flow
Montreal (central)	18–22 (pricey)	3.5–4.5%	$100–200/unit/month
Suburbs / South Shore	15–18	4.5–5.5%	$150–250/unit/month
Regions	10–14	5–7%	$250+/unit/month

Back to our triplex: GRM = 975,000 ÷ 48,000 = 20.3 (typical of Montreal, so pricey) and cap rate = 37,500 ÷ 975,000 = 3.85% (within range). Simple rule: if the cap rate beats your mortgage rate, leverage (borrowing earns you more than the credit costs) works in your favour.

And the famous American "1% rule" (a monthly rent of at least 1% of the price)? It's nearly unreachable here: with a median plex price in Montreal above $865,000 (QPAREB/APCIQ, early 2026), you'd need $8,650 in rent per month. In Quebec, rely on the GRM and cash flow instead.

Action point: filter first by GRM (drop plexes above 20 in Montreal), then confirm with cash flow and the cap rate.

---

Import the listing automatically (demo)

Typing a listing in by hand is slow and invites errors. WiseRock imports the listing (DuProprio, Realtor, Centris) straight into the calculator. The flow:

1. Paste the listing's address (URL).
2. The import fills in the price, the income, the taxes and the number of units.
3. The calculator returns the NOI, the cash flow, the GRM and the cap rate.
4. You adjust the normalized numbers (real rents, forgotten expenses).

Free or paid? The rental yield calculator is free, and so is the automatic import, unlimited: it's the fast lane to the same analysis, not a separate product. You always keep control of the numbers.

Why a tool rather than a spreadsheet? A tool removes formula errors and keeps the Quebec benchmarks up to date, which a downloaded .xlsx file doesn't guarantee. It also lets you compare several scenarios side by side.

Action point: analyze your next plex for free, then import the listing in one click, free when manual entry becomes the bottleneck.

---

Red flags that kill a deal

A few signals are enough to drop a plex before you go further:

• inflated income ("potential" rents instead of the real leases);
• a sale without legal warranty (about 75% of plexes in Quebec), which transfers the latent-defect risk to the buyer;
• a single vacant unit that can turn a triplex's cash flow negative: keep at least 6 months of reserve;
• major work to plan for (roof, foundation, plumbing stacks);
• the 5-unit threshold, which flips financing into commercial mode (higher down payment, qualification on the building).

Action point: a single unresolved red flag = renegotiate or pass. The detailed list is in our 12 red flags before you buy.

---

From "maybe" to an informed offer

Move to an offer only when the numbers hold up. Your decision thresholds:

• cash flow ≥ 0, ideally $100 to $200 per unit in Montreal;
• GRM under your market's threshold;
• cap rate above your mortgage rate (positive leverage).

On the bank's side: to finance an income property, the lender generally requires a debt service coverage ratio (DSCR) of at least 1.20 to 1.30 (a common bank standard in Quebec), a safety margin between the NOI and the payment.

To put in the offer: an inspection condition and access to the leases and the last 12 months of real expenses, plus the tax bill and the seller's declaration.

Action point: make your offer conditional on obtaining the leases and the real expenses. If you plan to keep buying, see how to finance several properties.

---

Common mistakes

1. Trusting the listing's "potential gross" income (optimistic rents, minimized expenses).
2. Forgetting the invisible expenses: vacancy, management (~5%), maintenance reserve (1–2% per year), energy.
3. Confusing gross yield, net yield and cash flow: what decides is the NOI and the cash flow.
4. Buying with negative cash flow while betting on appreciation alone (common in 2025–2026).
5. Applying the American "1% rule", unsuited to Quebec 2026 prices.
6. Ignoring the 5-unit threshold, which changes the whole financing picture (commercial instead of personal).

Action point: before you close, ask yourself four questions: real rents? all the expenses? cash flow ≥ 0? sale with or without legal warranty?

---

In short: pull out the five numbers, calculate the NOI then the cash flow, confirm with the GRM and the cap rate, and normalize everything. Never rely on the seller's table alone. Analyze your next plex for free, and import the listing in one click to save time.

Transparency and updates. The example amounts are realistic assumptions for 2026, to be replaced with your real numbers (leases, financial statements, tax bill). The GRM, cap rate and cash flow thresholds vary by area and comparable sales. The rental yield calculator is free; the automatic import is free and unlimited. An analysis replaces neither the building inspection nor the lender's approval. Figures and rules in force in June 2026.

---

Sources: QPAREB/APCIQ (median plex price in Montreal, early 2026); CMHC (down payment by property type, mortgage insurance, rental market); OACIQ (seller's declaration, sale without legal warranty); Tribunal administratif du logement (rent-setting guidelines). Market figures indicative for 2026, to be confirmed against your own file.

About WiseRock

WiseRock is a Canadian platform for real estate buyers and investors. We turn listings and financing assumptions into clear decisions: a free rental yield calculator, mortgage calculators, and automatic listing imports to analyze a plex in minutes instead of with a spreadsheet.