Return on investment calculations for UK buy-to-let property are frequently misquoted, misunderstood, and selectively presented — often by people trying to sell you something. Understanding how to calculate BTL returns properly, account for realistic 2026 running costs, and evaluate what constitutes a genuinely good deal is one of the most useful skills a UK property investor can develop.
This guide covers gross yield, net yield, and cash-on-cash return — with a worked example using real numbers, and an explanation of how buying below market value dramatically changes your ROI from day one.
Gross Yield: The Headline Number
Gross rental yield is the simplest measure and the one most often quoted in listing descriptions and property investment marketing. The formula is:
Gross Yield = (Annual Rent / Purchase Price) × 100
A property purchased for £150,000 that achieves £850 per month in rent has a gross yield of: (£10,200 / £150,000) × 100 = 6.8%
Gross yield is useful for quick comparisons between properties, but it does not reflect what you actually keep. It ignores every cost of ownership — which, in 2026, are substantial.
Net Yield: What You Actually Earn
Net yield deducts all running costs from the rental income before dividing by the purchase price. The formula is:
Net Yield = ((Annual Rent − Annual Costs) / Purchase Price) × 100
Realistic 2026 running costs for a single-let BTL
- Letting agent fees: 10–15% of gross rent for a fully managed service. On £850/month, that is £1,020–£1,530/year.
- Mortgage interest: At current rates (approximately 4.5–5.5% for a BTL product), interest on a 75% LTV mortgage of £112,500 at 5% is £5,625/year.
- Insurance: Landlord buildings and contents insurance, £400–£600/year.
- Maintenance and repairs: Budget 1% of property value annually — £1,500 on a £150,000 property.
- Void periods: Industry standard is one month per year — equivalent to 8.3% of gross rent, or £850 on this example.
- Landlord licensing: Selective licensing schemes in many UK councils now charge £500–£800 per property per five-year licence. Annualised, that is £100–£160/year.
- Accountancy and compliance: Annual tax return and property income accounting, £300–£500/year.
Total running costs on this example: approximately £9,800–£10,300/year. Against gross rent of £10,200, that leaves net income of roughly £0–£400/year — a net yield of 0–0.3%. This is why gross yield is a misleading number, and why many landlords who bought on apparently reasonable yields find themselves cashflow-negative once all costs are accounted for.
Cash-on-Cash Return: The Investor's Real Metric
Cash-on-cash return measures what you earn on the actual cash you have deployed — not the full purchase price. This is the most relevant metric for leveraged property investors. The formula is:
Cash-on-Cash Return = (Annual Net Cashflow / Total Cash Invested) × 100
Total cash invested includes your deposit, stamp duty, legal fees, survey costs, and any refurbishment. On a £150,000 property with a 25% deposit, that is typically:
- Deposit (25%): £37,500
- Stamp duty (3% surcharge for additional property): £4,500
- Legal fees and survey: £2,500
- Total cash in: £44,500
How BMV Purchase Price Transforms Your ROI
This is where below-market-value purchasing changes the arithmetic fundamentally. Consider the same property — market value £150,000, rental income £850/month — but purchased at 15% below market value for £127,500.
- Gross yield on purchase price: (£10,200 / £127,500) × 100 = 8.0%
- Mortgage interest (75% LTV on £127,500 at 5%): £4,781/year (vs £5,625)
- Annual net cashflow (all other costs unchanged): approximately £1,200–£1,600/year
- Deposit at 25% of £127,500: £31,875
- Total cash in (reduced stamp duty, same legal): approximately £36,750
- Cash-on-cash return: (£1,400 / £36,750) × 100 = 3.8%
More significantly, on day one of ownership you have £22,500 of equity above your mortgage (the £150,000 market value minus the £127,500 purchase price). If you refinance within 12–24 months at the surveyed market value, you can pull a significant portion of that back out, reducing your net cash deployed further and improving your cash-on-cash return materially.
What Makes a Good BTL Deal in 2026?
In the current UK market, with mortgage rates elevated and operating costs higher than a decade ago, the commonly cited benchmarks are:
- Gross yield of 8%+ provides enough headroom to remain cashflow-positive after a fully managed letting service and realistic cost provisions.
- Net yield of 5%+ is a reasonable target after all costs except mortgage finance.
- Cash-on-cash return of 6%+ for a leveraged deal (above the current risk-free rate) suggests the investment genuinely makes sense on a current income basis.
These thresholds are most achievable in Northern England, the Midlands, and parts of Scotland — where purchase prices are lower relative to achievable rents. In London and the South East, gross yields of 4–5% are common, and cashflow-positive investing typically requires significant equity or cash purchase.
How AI Lead Scoring Helps Find High-Yield Opportunities
The challenge for most investors is not calculating yield — it is finding properties where the numbers work before someone else does. Manually scanning every listing in your target area, estimating rental income, cross-referencing purchase prices against comparables, and identifying motivated sellers is genuinely time-consuming.
DealMind's AI scoring engine does this automatically. Every active listing is evaluated for motivated seller signals — price reduction history, days on market, listing language — and cross-referenced with local rental data and sold price evidence. Listings that meet your yield and discount thresholds are delivered as qualified leads, with the relevant supporting data already calculated.
The result is that your daily sourcing becomes a review of the best ten leads from across thousands of listings — rather than manually searching through Rightmove and doing the maths yourself. For investors targeting 8%+ gross yields on motivated-seller properties, this is the difference between finding one deal every two months and maintaining a consistent acquisition pipeline.