Rental investment simulator
The rental investment simulator works out how profitable a rental purchase would be: cash flow, yields, gearing, an overall grade and a projection over the holding period. You reach it from the “Tools” section, then “Investment simulator”.
Everything is recalculated in your browser as you type: there is no “Save” button.
Important!
A simulation is never kept. If you leave the page or reload it, every field returns to its default value.
Use “Print” or “Download” before leaving the page if you want to keep a record of it.
Starting from a new project or an existing property
At the top of the “Property” block, the “Property to analyse” list offers “New project” — the fields then hold example values — or one of your properties. Choosing a property pulls in its record: acquisition cost and acquisition fees, renovation, estate agent fees, rent, service charges, property tax, market value and tenancy type. The personal contribution is derived from the recorded loan; the borrower insurance rate is only carried over when it is recorded as a percentage.
Anything missing from the record comes across as 0, and switching property resets every field first. Only the properties you have access to are listed, excluding archived ones and the trash — see create, edit or delete a property or unit.
Choosing the level of detail
Three tabs decide how many fields are shown: “Beginner” sticks to the essentials; “Advanced” adds renovation, furniture, service charges, vacancy, building service charges, maintenance, management and tax assumptions; “Expert” adds the annual rent increase, detailed tax settings, resale, the annual projection and the IRR.
Going back to a lower level hides the fields but keeps their values: they are still taken into account in the calculation.
Filling in the assumptions
The left-hand column groups the assumptions by block: “Property”, “Financing”, “Rental income”, “Operating expenses”, “Tax assumptions” and “Resale assumptions”. “Loan amount” and “Monthly amount” cannot be typed in: the loan is the total cost minus the contribution, and the monthly amount includes the borrower insurance. “Maintenance provision” and “Letting management fees” are expressed as a percentage of the rent; “Market value” replaces the acquisition cost as the basis for appreciation.
If a value is inconsistent — a zero acquisition cost or loan term, a rate above 20%, vacancy outside 0 to 100%, a contribution higher than the total cost — the “Incomplete or inconsistent data” banner replaces the grade and says what to correct.
Reading the results
The right-hand column updates on every keystroke:
- the grade, from A to F, and its comment;
- “Monthly cash flow — after tax”, with the cash flow before tax, the annual cash flow and a ten-year bar chart;
- “Gross yield”, “Net yield” and “Net-net yield”, each tile recalling its formula;
- “Break-even rent”, the rent at which the cash flow reaches zero;
- “Total investment” and “Loan-to-value (LTV)”;
- “Risk score” out of 100: gearing, cash flow margin, vacancy and gross yield. The lower it is, the safer the deal.
At “Expert” level, the “Annual projection”, the “Estimated resale value”, the “Net capital gain” and the “IRR” are added.
How the grade is worked out
A and B: positive cash flow after tax, with a low or moderate risk score. C: cash flow that is tight or slightly negative. D: a monthly loss you accept. F: heavily negative cash flow or very high risk. The grade follows entirely from your assumptions — two extra points of vacancy are sometimes enough to change it.
How tax is modelled
The “Tax assumptions” block only exists on the French version of the site. Elsewhere no tax is modelled: the cash flow after tax equals the cash flow before tax.
In France, “Tenancy type” drives the rest: “Unfurnished letting”, “Furnished letting” or “No tax modelling”. The “Tax system” list adapts to that choice — “Micro-foncier (30% allowance)” or “Actual expenses regime (deductible actual expenses)”, “LMNP actual regime + depreciation” or “Micro-BIC (50% allowance)” — then you fill in your “Marginal tax rate” and “Social security contributions”. The “Expert” level opens up the deductions, the depreciation and the detail of the capital gains tax.
Important!
The tax calculation is a simplified estimate: the rules depend on your personal situation.
It models neither the surcharge on large capital gains, nor the flat-rate allowances for costs and works, nor the property loss carry-forward, nor the ceilings of the micro regimes. Talk to an accountant before committing.
Comparing two properties
The “Compare” tab puts “Property A” and “Property B” side by side, thirteen fields each, pre-filled with example values and independent of the “Single property” tab. The table compares the total investment, the loan, the monthly amount, the cash flows, the yields, the break-even rent, the LTV, the risk score and the grade, then names a “Winner” row by row.
Testing how solid it is with the scenarios
The “Scenarios” tab replays what you entered in “Single property” three times: “Cautious” (rent −5%, vacancy +2 points, expenses +10%, rate +0.5 points), “Base case” (your data, the only card to show the grade) and “Best case” (rent +5%, vacancy −1 point, expenses unchanged). The two side cards show the gap against the base case. An investment is solid when the cautious scenario still produces an acceptable cash flow.
Printing or downloading the simulation
The “…” menu at the top right offers “Print”, which opens the laid-out simulation in a new tab, and “Download”, in Adobe PDF, Word and Open office formats. The document carries the grade, the results, your data, the resale and the annual projection, even from the “Beginner” level.
Only the “Single property” tab is exported: the comparison and the scenarios are not. If any fields are inconsistent, the export stops and the errors are shown.
