Strategy calculator
HMO Calculator UK -- Free Yield & Cashflow
Houses in Multiple Occupation generate the highest cash yields in UK residential property -- and the highest operational complexity. This free calculator rolls up per-room rent, void allowance, bills, management, and HMO licensing cost against the purchase price, and gives you the net yield and monthly cashflow that actually matter. No sign-up wall.
What does the HMO calculator compute?
The HMO calculator takes the inputs that drive HMO returns differently to single-let BTL. Number of lettable rooms, average rent per room (or per-room rent for mixed sizes), void allowance per room (typically 8-12% versus 4% for single-let), management fee (12-15% versus 10%), and HMO-specific operating costs: bills (gas, electric, water, council tax, internet, TV licence) which the landlord typically covers, cleaning of communal areas, fire alarm servicing, gas safety, EICR, and the amortised cost of the HMO licence over its 5-year term.
Outputs are designed to make HMO economics legible: gross HMO yield (annual rent over purchase price plus conversion cost), net HMO yield after all operating costs, monthly cashflow after mortgage payment, cost per door, and a sense check against comparable single-let yield in the same area. Most professional HMO investors target 12%+ gross yield and 8%+ net yield -- the calculator lets you see immediately whether a deal hits those thresholds before you commit to the conversion work and licensing process.
The calculator also handles the conversion case: if you are buying a 3-bed terrace to convert to a 5-bed HMO, you can input the conversion budget and the calculator will treat that as money in alongside the purchase price for yield and ROI purposes.
UK HMO regulation -- what changes the underwrite
Mandatory licensing. Properties with 5 or more unrelated occupants forming two or more households require a mandatory HMO licence from the local authority. Licence fees vary widely (typically £500-£1,500 over a 5-year term). The application requires floor plans, fire safety assessment, gas safety, EICR, room size compliance, and amenity standards (kitchen and bathroom ratios relative to occupant count).
Additional and selective licensing. Many councils operate additional licensing schemes capturing properties with 3+ unrelated occupants (smaller HMOs), and selective licensing applying to all rented properties in designated wards. Coverage maps are on the council website -- always check both the licence register and the local plan before underwriting. Operating an unlicensed HMO carries fines up to £30,000 per offence and Rent Repayment Orders that can claw back 12 months of rent.
Article 4 directions. In many desirable HMO areas (university towns, parts of London, Manchester, Liverpool, Nottingham), Article 4 directions remove permitted development rights to convert a C3 dwelling-house to a C4 small HMO. Without the right under permitted development you need full planning permission, which is often refused on policy grounds (street saturation thresholds, the "tipping" rule). An Article 4 area on your target street can kill the HMO strategy before you start.
Common HMO mistakes
- 1 Modelling 100% occupancy. HMO rooms turn over more often than family lets -- average tenancy length is 6-12 months. Realistic void allowance is 8-12% per room, not 4% per property. Underwrite with the higher number; if it still works, you have a real deal.
- 2 Forgetting council tax. Most HMO licensing splits council tax liability onto the landlord (not the tenants). On a Band C HMO in Manchester that is £160-180 per month you have to absorb. Always include it in your operating costs.
- 3 Using a standard BTL mortgage. Most high street BTL lenders refuse 5+ room HMOs or licensed HMOs altogether. You need a specialist HMO product (Paragon, Foundation, Kent Reliance, LendInvest), which prices 0.5-1% above standard BTL and requires a more involved valuation process.
Underwrite an HMO room-by-room
Open the calculator free, or sign up to Propreneur to manage your HMO with per-room rent rolls, licence renewal alerts, and EICR / gas safety tracking built in.