Calculator 1:

Use this calculator to calculate the ROI of your Granny Flat as a %. It also shows your Net Annual (and Monthly) Return as a dollar value - which is how much extra cash you will earn by building a Granny Flat.

Cost to Build a Granny Flat $
Rental Income Per Week - Granny Flat $
Rental Income Per Year - Granny Flat $19,760
ROI - on Granny Flat 19.8%
Current Mortgage Interest Rate (as a %) %
Annual Repayments on Granny Flat Investment $7,500
Net Annual Return on Investment $12,260
Net Monthly Return on Investment $1,022

Calculator 2:

Use this calculator to compare the ROI & Net Annual Return of your Investment Property before and after building a Granny Flat on it. It also shows you whether your Investment is a Negative or Positive Geared Investment.

Investment Property Only

Investment Property & Granny Flat

Cost of Buying an Investment Property $ Cost of Buying an Investment Property $
Cost of Building a Granny Flat $
Cost of Total Investment $500,000 Cost of Total Investment $600,000
Rental Income per week - Main Dwelling $ Rental Income per week - Main Dwelling $
Rental Income per week - Granny Flat $
Total Rental Income - per week $550 Total Rental Income - per week $930
Rental Income per year - Main Dwelling $28,600 Rental Income per year - Main Dwelling $28,600
Rental Income per year - Granny Flat $19,760
Total Rental Income - per year $28,600 Total Rental Income - per year $48,360
ROI - on Investment Property 5.7% ROI - on both Properties 8.1%
ROI - on Granny Flat alone 19.8%
Current Mortgage Interest Rate (as a %) % Current Mortgage Interest Rate (as a %) %
Annual Repayments on Total Investment $37,500 Annual Repayments on Total Investment $45,000
Net Annual Return on Investment $-8,900 Net Annual Return on Investment $3,360
This is a Negative Geared Investment This is a Positive Geared Investment
By adding a Granny Flat to this Investment Property it has improved the Net Annual Return by $12,260
By adding a Granny Flat to this Investment Property it has improved the ROI by 40.91%