CalculateurPlex
Custom calculator to analyse plex profitability: cap rate, cash flow, CMHC, equity.
CalculateurPlex helps you evaluate an income property in 30 seconds: cap rate, monthly cash flow, CMHC rules, 25-year equity, market comparison and owner-occupant scenario — with secure payment for the instant result.
Measured performance
Performance
Accessibility
SEO
Best practices
Measured with Google Lighthouse (desktop) on August 16, 2026. Real scores can vary with network conditions and later site updates.
The challenge
Let an investor size a plex's profitability quickly, without a complex spreadsheet or an accountant's fee.
The approach
Calculation logic specialised for the Quebec market (CMHC rules built in), a guided input UI, instant results and Stripe checkout.
The result
A clear, reliable calculator that turns a tedious analysis into a few seconds of work.
Technical decisions
Stripe payment, never storing a card
The detailed result unlocks with a one-time payment. I chose Stripe so payment security is fully delegated — no card data ever touches or sits on the site — while keeping the experience smooth: you pay and get the analysis in the same flow.
CMHC rules and Quebec tax reality, encoded
A generic profitability calculator would be wrong for a Quebec plex. The logic includes CMHC schedules and local specifics (down payment, ratios) so cap rate, cash flow and equity reflect the actual market — not a North-American average.
Instant calculation, guided interface
Instead of a long form, input is guided and the result appears in seconds. That's what makes it possible to evaluate a building “in 30 seconds” without a spreadsheet or an accountant — an architecture choice confirmed by a 99/100 Lighthouse performance score.
One challenge, one solution
The challenge
How do you present a dense financial analysis — cap rate, monthly cash flow, 25-year projected equity, owner-occupant scenario — without drowning an investor who is not an accountant?
The solution
I split input (a few essential fields) from output (results ranked from most useful to most detailed). Heavy calculations run once on submit, which keeps the UI responsive and readable despite dense logic behind the scenes.