Buy-to-Let Calculator

See a rental property’s cash flow, gross and net yield, and the return on the cash you put in, after the mortgage and running costs in the UK.

Purchase price

Deposit

Rent

A month

Mortgage rate

Mortgage type

More options· Running costs, empty weeks and buying costs

Empty

% of the year

Agent fee

% of rent

Repairs

% of price a year

Council tax (if empty)

A year

Landlord insurance

A year

Service charge

A month

Costs to buy

Taxes and fees, % of price

It costs you

£21/mo

Rent left after the mortgage and running costs, before tax

Gross yield: 6.0%
Net yield: 4.0%

What this means

You’d top it up by £21 a month. It would pay for itself at a rent of about £1,274 a month. On the £80,000 you put in, that’s a -0.3% cash return in the first year, before any rise in the property’s value.

Buy-to-let buyers pay a 5% Stamp Duty surcharge, and mortgage interest only gets 20% tax relief, so higher-rate taxpayers can owe tax even when cash flow is low.

Next step

The first year

Rent collected	£14,400
Letting and management	−£1,440
Repairs and upkeep	−£2,500
Insurance	−£400
Mortgage payments	−£10,313
Cash flow	-£253

What the numbers mean

Gross yield: a year’s rent as a share of the price. Quick to compare, but ignores costs.
Net yield: rent after running costs, before the mortgage.
Cash return: cash flow as a share of the deposit and buying costs you put in.

Assumptions in this estimate

The first year only, before tax. Rents, rates and costs change, and you’ll also gain or lose as the property’s value changes.
Mortgage payments include paying off the loan on a repayment mortgage: that part builds your equity rather than being a cost.

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How the calculator works

Price, deposit and mortgage rate, and whether the mortgage is repayment or interest-only.
Rent, and the share of the year it might be empty.
Running costs: management, repairs, insurance, property tax or rates, and any strata or service charges.

Example

A £250,000 buy-to-let with a 25% deposit on a 5.5% interest-only mortgage, renting for £1,250 a month, with insurance and a 10% letting agent fee:

	Result
Cash flow a month	-£21
Gross yield	6.0%
Net yield	4.0%

These are first-year figures, before tax and any change in the property’s value.

Last updated October 20, 2026

Frequently asked questions

What is a good rental yield?

It depends on the area: cheaper areas often have higher yields but slower price growth. A gross yield of 5% to 7% is common; compare the net yield, after costs, between properties.

What is the difference between gross and net yield?

Gross yield is a year’s rent as a share of the price. Net yield takes off running costs such as repairs, insurance, rates or property tax, and management, but not the mortgage.

Why is my cash flow negative?

At today’s interest rates, rent often doesn’t cover the mortgage and costs, especially with a small deposit. Investors then rely on the property’s value rising, which isn’t guaranteed.

Why do higher-rate taxpayers pay more on buy-to-let?

Mortgage interest can’t be deducted from rental income. Instead you get a tax credit of 20% of the interest, so higher-rate taxpayers can owe tax even when the rent barely covers the costs.