How to analyse a buy-to-let deal without a spreadsheet

If you've ever browsed Rightmove on your phone, found a promising property and then spent the next hour building a spreadsheet to crunch the numbers, you know the pain. The formulas break. The assumptions change between deals. And by the time you've finished, someone else has made an offer.

Buy-to-let analysis doesn't need to be this complicated.

The Problem with Spreadsheets

Most UK investors rely on spreadsheets they've built themselves or downloaded from a forum. These tools have a few common problems:

Inconsistent assumptions. Your void rate changes from deal to deal. Your interest rate is sometimes fixed, sometimes variable. You forget whether you included management fees on the last property you analysed.

Broken formulas. One wrong cell reference and your entire yield calculation is off. Good luck spotting the error in a sheet with 50 rows.

No stamp duty handling. Calculating stamp duty for additional properties is surprisingly tricky. Most spreadsheets either get it wrong or require you to calculate it separately and paste in the number.

Section 24 confusion. If you're a higher rate taxpayer, Section 24 changes the economics of your deal. Very few spreadsheets model this correctly.

What a Good BTL Analysis Actually Needs

A proper buy-to-let analysis should answer a few key questions:

1. What's the gross yield? This is your annual rent divided by the purchase price. It tells you whether the property is even worth investigating.

2. What's the net yield? After voids, management, insurance and maintenance, what's actually left?

3. What's the cash-on-cash return? If you're using a mortgage, how much cash do you need to put in and what return does that cash generate?

4. What's the monthly cashflow? After all expenses and mortgage payments, what lands in your pocket each month?

5. Does it stack after tax? If you're a higher rate taxpayer, Section 24 might turn a profitable deal into a loss-maker. You need to model this.

The Role of Assumption Profiles

The secret to consistent deal analysis is using the same assumptions across every property. This means:

• Same void rate (e.g. 8% or one month per year)
• Same management fee (e.g. 10% of rent)
• Same maintenance allowance (e.g. £500/year)
• Same interest rate stress test

When you use consistent assumptions, you can actually compare deals to each other. Property A has a 6.5% net yield and Property B has a 7.2% net yield—now you're comparing apples to apples.

Why Mobile Matters

The best deals go fast. If you're browsing Rightmove on your commute and you see something interesting, you need to know within minutes whether it's worth pursuing.

Opening your laptop, finding your spreadsheet, inputting all the details and waiting for the formulas to calculate is not a realistic workflow. By the time you've done all that, you've probably forgotten about the deal anyway.

Mobile-first analysis tools like DealSheet AI solve this problem. Paste the listing link, enter your offer price and get a full analysis in seconds—all on your phone.

Key Metrics to Focus On

When analysing a buy-to-let, focus on these numbers:

Gross yield above 6%. Below this and you're probably looking at a capital growth play rather than an income investment.

Net yield above 4%. Once you've deducted all costs, you want at least 4% to make the hassle worthwhile.

Cash-on-cash above 8%. If your money can earn 5% in a savings account with zero effort, your property investment should beat that comfortably.

Positive monthly cashflow. Even if the numbers work on paper, a property that loses money each month will drain your reserves over time.

Conclusion

Buy-to-let analysis doesn't need to take hours. With the right tool and consistent assumptions, you can evaluate any property in under a minute. The key is to stop reinventing the wheel with every deal and start using a system that handles the complexity for you.

DealSheet AI was built specifically for UK investors who want fast, accurate analysis without the spreadsheet headaches. Try it free for 3 days and see how much time you can save.