Calculation methodology

Rent Calc does not try to predict the future market and does not issue an investment recommendation.

A scenario is not just refurbishment. It includes the initial spend, the expected rent, recurring costs, taxes, vacancy, rent growth, property value changes, and the way spare cash flow may keep working afterwards.

For flats that already have a usable finish, one typical scenario can be a light cosmetic refresh: a small update before letting that should be evaluated like any other CAPEX.

Each scenario is a set of assumptions about how the flat will be prepared and let out.

The base scenario is the reference point. In the current version it is defined with no initial CAPEX: CAPEX = 0.

Other scenarios differ by upfront spend, expected rent, costs, vacancy, rental growth, and other assumptions.

First, define the starting situation: a new build without finishing, a new build with developer finishing, a flat after tenants move out, older housing stock, a modern residential complex with existing renovation, or a rent-versus-sell decision.

Then create 3-5 scenarios with different upfront spend, rent levels, costs, and vacancy assumptions.

For flats that already have a usable finish, it is usually worth adding a light cosmetic refresh as a separate scenario: it is a clear middle option between “rent as is” and “do a serious refurbishment”.

After that, the model compares not the ideas themselves, but their financial result over the same calculation horizon.

• New build without finishing: minimal fit-out, basic refurbishment with kitchen and appliances, full setup, stronger refurbishment for higher rent.
• New build with developer finishing: rent as is, refresh weak points, add furniture and appliances, fully furnish the flat.
• Flat after tenants move out: rent again as is, do a light cosmetic refresh, replace furniture and appliances, improve the setup.
• Older housing stock or resale flat: minimal preparation, cosmetic refresh, basic rental refurbishment, full refurbishment, walk away from the purchase or sell and place capital in savings.
• Modern residential complex with existing renovation: rent as is, cosmetic refresh, add missing furniture and appliances, stronger redesign.

• property value and available spare capital;
• annual property value growth, which affects final capital including the apartment;
• CAPEX: refurbishment, light cosmetic refresh, furniture, appliances, and preparation for letting;
• expected rent for each scenario;
• taxes, utilities, commissions, and other recurring costs;
• property management or platform fees;
• a reserve for future repairs and upkeep;
• vacancy, when the flat is not let and produces no rental income;
• rent growth and property value growth over time;
• the alternative return on spare cash, including savings and compound return.

For each scenario, the model first estimates potential rent, then reduces it for vacancy, taxes, and recurring costs.

Initial spend on refurbishment, cosmetic refresh, furniture, or appliances reduces spare capital at the start of the calculation.

Positive cash flow may continue working through the alternative placement of spare funds.

Savings in Rent Calc are used as the base alternative for spare cash.

The model can account for compound return: spare funds and positive rental cash flow may be routed into the alternative place for money and continue working inside the calculation horizon.

The savings benchmark is not there to say that savings are always better. It is there to compare property scenarios against the alternative return on capital.

If you need to compare renting with selling the flat, the full-capital savings benchmark can be read as the option “sell the property and place the money separately”.

In that case, the flat is treated as not producing rent, and the result is formed by the return on the full capital over the selected horizon.

This allows the model to compare keeping the property and earning rent with the alternative where the capital no longer remains in the property and works in savings at the selected rate.

• Scenario final capital.
• Net cash flow.
• Payback of additional spend.
• Difference versus the base scenario and savings benchmark.
• Cash flow, final capital, difference, payback, and scenario result as the main terms.

The charts show how each scenario changes over the selected calculation horizon.

You can use the charts to assess how the scenarios' final capital changes over time, what cash flow remains after costs and vacancy, and when extra spend starts to pay back.

The best scenario is not always the one with the highest rent.

A stronger refurbishment or full furnishing may lose if the rent uplift does not cover the upfront spend.

A light cosmetic refresh can be a strong middle option if it improves presentation and rent without large CAPEX.

If the winner changes after a small input tweak, the scenario deserves another review.

Rent Calc scenarios are structured: inputs, assumptions, metrics, and charts.

There is no built-in AI chat in the current version.

Rent Calc compares scenarios using the parameters you enter and the assumptions you set.

The model helps you see the differences between options, but it does not predict the actual behaviour of the market, tenants, contractors, or bank rates.

• registration and a personal account are not available yet;
• the number of scenarios is fixed: the current setup uses 5 scenarios;
• one of the scenarios is the base case: CAPEX = 0;
• there is no built-in AI chat for result analysis yet;
• the calculation depends on the entered parameters and is not financial, tax, or legal advice.

STIV Labs designs applied solutions, scenario models, and decision-support interfaces for business problems.

Rent Calc grew out of a real owner’s problem: comparing letting scenarios for a flat, assessing the payback of a cosmetic refresh, furniture and appliances, and testing the sale-and-savings alternative. The calculator shows two key metrics: net income for each scenario and the final total capital over the chosen horizon.