If you delay house purchase, that house seems to appreciate at the general inflation rate but when you purchase it switches to the appreciation rate you input on that house. May be more accurate if house appreciates at the rate you specify both before and after your purchase. For example, a house could be appreciating faster than inflation. In that case, the tool will tell you saving is the best plan but in fact you will wait 5 years and be surprised that you are priced out of that market and should have actually bought 5 years ago and not saved.