HMO Yield Calculator: How to Work Out Your Real Profit in 60 Seconds

Why the Yield Number on Most Listings Is a Fantasy

Property portals and sourcing agents almost always quote gross yield. It's the headline number: annual rental income divided by purchase price, multiplied by 100. On a 6-bed HMO where each room goes for £500 per month, that's £36,000 per year in rent. Buy the property for £200,000 and the gross yield is 18%. Sounds extraordinary.

And it is — because it's not real.

Gross yield assumes 100% occupancy, zero management fees, no maintenance, no licensing costs, no compliance spend, and no voids. None of those assumptions survive contact with an actual tenancy. According to HMO Checker's Q1 2026 data, average HMO gross yields across the UK sit at around 9.6–10%, down from 10.4% the previous year. Even at that more realistic level, gross yield is still the fantasy version of the number.

The figure you actually need — the one that tells you whether a deal is worth doing — is net yield.

The 60-Second Gross Yield Formula (Step 1)

Start here. You need two numbers:

1. Annual room rents — multiply your monthly room rate by the number of rooms, then by 12. 2. Purchase price — the actual price you pay, not the asking price.

Formula: (Annual room rents ÷ Purchase price) × 100 = Gross yield %

Using the AgentHMO-style example that circulates widely in HMO training circles: 6 rooms at £500/month = £3,000/month = £36,000/year. At a £200,000 purchase price, gross yield = 18%.

Write that number down. Then immediately accept that you will never see it.

Gross yield is useful for one thing only: quick comparison between properties before you do the real work. If a property's gross yield is below 8% in a high-demand HMO market, the net yield almost certainly won't stack. If it's above 12%, it's worth running the full numbers. That's the only job gross yield has.

The Deductions Most Investors Forget (Step 2 — This Is Where Deals Die)

Here is where the maths gets honest. Net yield strips out every real cost of running the HMO. Based on the methodology outlined by Adept Mortgages and corroborated by THMOMB's 2026 statistics, the standard deductions you must include are:

— Management fees: Typically 10–15% of gross rent if you use a letting agent. On £36,000 that's £3,600–£5,400 gone immediately. — Void periods: Industry standard assumption is 4–6 weeks per room per year across a portfolio. On a 6-bed that could mean 1–2 rooms empty at any point. Budget 8–10% of gross rent as a void allowance. — Maintenance and repairs: HMOs have more tenants, more wear, more call-outs. A realistic budget is 8–12% of gross rent annually, higher for older stock. — HMO licensing: Mandatory licensing fees vary by council but typically run £500–£1,500 every 5 years per property. Annualised, that's £100–£300/year. — Compliance costs: Fire safety, electrical inspections (EICR every 5 years), gas safety (annual), EPC upgrades. Budget £300–£600/year for a well-maintained property. — Mortgage interest: If you're using finance, this is your biggest deduction. On a £150,000 HMO mortgage at a 5.5% rate, interest-only payments run roughly £8,250/year.

Total these up on our 6-bed example and you're looking at deductions of £12,000–£18,000 against £36,000 gross rent — before mortgage costs.

Net yield formula: ((Annual rent − All annual costs) ÷ Purchase price) × 100

On our example, after deducting £14,000 in running costs (a mid-range estimate), net income is £22,000. Net yield: 11%. Add mortgage interest and the cash-on-cash picture changes further still — but even at 11% net, this is comfortably double what Quartico reports as the average standard BTL yield of 5–6%.

That's the honest version of the number. And it's still good.

The One Trade-Off Nobody Talks About

HMOs deliver higher yields than standard BTLs. That is not in dispute — Foot Forward's analysis of post-cost HMO returns consistently shows superior net returns versus single-let properties, even after management costs are included.

But here's the trade-off I think most educators gloss over: HMO running costs are not just higher in absolute terms, they're less predictable. A single-let property with a long-term tenant can run for months without a call-out. An HMO with six different tenants will generate maintenance requests, tenancy changeovers, and compliance renewals on a rolling basis. Your void risk is spread across more rooms — which is actually a structural advantage — but your management complexity is significantly higher.

I'm not saying don't do HMOs. I'm saying model the costs conservatively, not optimistically. If your deal only works on best-case assumptions, it doesn't work.

The investors I've seen struggle with HMOs are almost always the ones who ran the gross yield number, got excited, and skipped the deductions. Don't be that person.

How to Find HMOs With the Numbers Already in Front of You

Running this calculation manually for every property you look at is genuinely time-consuming — especially when you're trying to assess multiple markets simultaneously. The bigger problem is finding the properties in the first place. HMOs don't appear on Rightmove the way standard BTLs do. Many are off-market, or listed in ways that make them hard to identify without knowing exactly what to look for.

That's the gap [ZARSK](https://zarsk.co.uk) was built to fill. It's one of the largest HMO databases in the UK, constantly updated, and built specifically for investors who want to find genuine HMO opportunities — not trawl through general property listings hoping something fits.

Once you've found a deal that looks right on paper, the next challenge is finance. Getting an HMO mortgage as a new investor is harder than most people expect, and freeing up equity in an existing portfolio — whether that's BTL or HMOs — is a problem even experienced landlords run into regularly. ZARSK's regulated finance partners specialise in exactly this: HMO mortgages and equity release for property investors. You can find out more at [zarsk.co.uk/finance-property](https://www.zarsk.co.uk/finance-property).

The calculation method above takes 60 seconds once you have the numbers. Getting the right numbers — on the right properties, with the right finance — is what takes longer. That's where having the right tools and the right specialist support makes an actual difference.

Gross yield will keep appearing on listings, in pitch decks, and in conversations with agents who want you to get excited before you get analytical. That's not going to change. What can change is the order in which you do your maths. Run gross yield to filter. Run net yield to decide. And if the net yield still looks strong after you've been brutal with the deductions — that's a deal worth pursuing. The HMO market in Q1 2026 is averaging 9.6–10% gross per HMO Checker, which translates to real net yields that still comfortably outperform standard BTL. The opportunity is genuine. The numbers just need to be honest.