Church planting: a simplified financial approach

Let's say you want to plant a church cold (just you & your wife & kids if you have them). How long until you are financially viable?

Ok, this is me just thinking out loud, my facts and figures below are entirely anecdotal and based on my own experiences. All reasoning is bunk guesswork. 

Let's just say you graduated from theological college and you got all fired up and decided to plant a completely new church somewhere you've never been before. 

You touchdown in a new area with no Christian contacts and you start witnessing faithfully and thoughtfully with mixed reaction. 

You start a weekly Sunday home church targetted at young people. 

You have some success and over 12 months gain 6 converts, two of which are really committed. 

Of the six, 4 come irregularly and contribute around $30 each time they come. After crunching the numbers you work out that in general, 2 irregular members turn up per week. They contribute $60 per week to church costs. 

2 members are very faithful, attend every week and contribute $50 each per week. 

That means that over 12 months the church has gone from generating no income to generating  $160 per week which is $8320 per year. On average $15 per week per irregular member, and $50 per week per faithful member. 

Let's just say that those who join, join permanently. No one leaves to go to another suburb or church. 

Let's also say that the fruit is constant and the same amount join the next year , and the next year and so on. 

Stipend is about $70K, modest family housing is around $30K. At what size would this congregation be to be naturally supporting a minister on stipend? 

Not accounting for inflation.

There would have to be 12 groups the same size. Which is a church of 72 giving adults. 24 of these are strongly faithful, 48 are irregular coming twice per month. 

This congregation will take 12 years to gather. 

It does not have a building. Unless you count the minister's house which they are renting.  

The building project

Let's just say they want a more permanent arrangement so the church decides to buy a building. At today's Sydney prices let's guess that that will cost $3-4million including a rectory (in all honesty, quite unlikely!).  

I hate to think what sort of time it would take to be able to afford a building and paying it off.

It would have to grow steadily to 150 members (let's say another 12 years) in order to secure another $100K mortgage payback power. 

Let's say they then pay off their building in 25 years. Which presumes they have likely grown in size and collected a significant amount of one off donations to drastically reduce the mortgage repayment timeframe. 

There you go. That took 48 years. 

Yes, there are plenty of massive presumptions in there, enough to entirely undermine the reasoning. But not so many to undermine the point: what SHOULD a church plant look like 50 years on.