First work out the actual annual rent you will receive after deducting agent's commission, repairs and renewals and any service charges and insurance.
Enter this amount into the Net Annual Rent box.
Then enter the TOTAL purchase price including transaction expenses, surveys etc into the Total Purchase Price box.
Click Calculate. This will give your real annual yield on the investment. Obviously how much you actually receive in your pocket will depend on your own personal borrowing costs etc.
Net Annual Rent £
Total Purchase Price £
Rental Yield %