Input Parameters
Your current total savings that you are comfortable investing (house or investments)
Your share of the house price. This is the full house price excl. purchase costs if you are buying alone.
Your current monthly rent payment.
Remaining income after all expenses and rent, available for savings.
How far in the future you want to calculate the results. Should be at least your mortgage term.

The length of the mortgage loan. A range of 15-30 years is common.
The minimum down payment required for a mortgage. A range of 10-20% is common.
Notary fees etc. associated with buying a house. A range of 5-10% is common.
The inflation rate of the house price. Average increase rate over the last 30 years is 3.5% for US.
Your expected yearly return on your investments. Should be bank interest rate if not planning to invest. Average for US stock market over last 30 years is 9%.
Interest rate for minimum mortgage scenario (often lower due to higher down payment)
The inflation rate of the goods and services you consume. Average yearly inflation rate over the last 30 years is 2.5% for US.
Results