Population growth formula?

[weem]

Can someone point me to a program, or formula of some kind that could help me generate some population growth numbers?

For example, if a place started with 200 people - how many would they have after, say, 1000 years.

I know there are factors like people coming to this area from another area, etc, but in general, I can't seem to find a calculator or formula for this.

 

[malraux]

Can someone point me to a program, or formula of some kind that could help me generate some population growth numbers?

For example, if a place started with 200 people - how many would they have after, say, 1000 years.

I know there are factors like people coming to this area from another area, etc, but in general, I can't seem to find a calculator or formula for this.

Well, such things are either dirt simple or crazy complex, depending on how accurate you want the model to be. A simple model would be something like

pop_current = pop_original * (per year growth rate) ^ number of years

per year growth rate should be expressed as something like (pop_current/pop_previous) that is if this year there were 101 people and last year there were 100 people the per year growth rate was 101/100 = 1.01 which is a 1% growth rate.

so lets assume a 1% growth and your other numbers. 200*1.01^1000 = 4,191,831

Obviously, this doesn't take into account stuff like declining resource availability, increased disease, etc.

 

[Ferret]

In simple terms the growth is exponential, with a formula something like N=b*N0*e^(a*t). With N and N0 being the population at the current time and the start time, and a and B being co-efficients.

The problem is, is this place temperate? Then it should increase steadily (maybe?) Artic might make it tougher for them to establish a larger community and thus be able to grow. Tropical places might have diseases like malaria which will keep the population down with a high death rate. Lots of factors.

 

[cdrcjsn]

You also need to consider tech levels. Better technology allows for faster growth.

Just do a random google search for population growth models.

Here's one I found in less than a minute of googling: Medieval Demographics Made Easy

 

[kitsune9]

You also need to consider tech levels. Better technology allows for faster growth.

Just do a random google search for population growth models.

Here's one I found in less than a minute of googling: Medieval Demographics Made Easy

Excellent resource on population building.

 

[mach1.9pants]

1+1=3.......after 9 months and, from my experience, 1+1=6 after about 6 years

I'd be interested to see what other sites come up, the demographics one above I use often, especially the generators at the bottom.

 

[Wulf Ratbane]

Assuming this is a world-building question, my response is: Put as many people there as you (the DM) need.

Seems an awfully fiddly thing to want to know, especially if the "correct" answer doesn't end up serving your needs.

 

[malraux]

Assuming this is a world-building question, my response is: Put as many people there as you (the DM) need.

Seems an awfully fiddly thing to want to know, especially if the "correct" answer doesn't end up serving your needs.

In truth, that's the best answer. And realistically, the population will rise until it hits a limiting factor like food, diseases, or angry orcs. So really, the best answer is to decide how large you want the population to be.

 

[Mercurius]

Can someone point me to a program, or formula of some kind that could help me generate some population growth numbers?

For example, if a place started with 200 people - how many would they have after, say, 1000 years.

I know there are factors like people coming to this area from another area, etc, but in general, I can't seem to find a calculator or formula for this.

I think you're approaching this backwards. The answer to your example is simple: As many as you want there to be. But if you want to go deeply into realism you should turn it around and not ask "how many would there be after 1,000 years" but "how did there come to be this many people."

How many people were there in New York City in 1500? None. How many are there now, 500 years later? 9 million in the city, 16 million in the metro area. How many were in Phoenix 100 years ago? Not many. How many now? Over 5 million. The point being, major growth can occur very rapidly, but it depends upon the industry, migration patterns, etc.

 

[weem]

Thanks everyone, much appreciated

Assuming this is a world-building question...

It is.

...my response is: Put as many people there as you (the DM) need.

Seems an awfully fiddly thing to want to know, especially if the "correct" answer doesn't end up serving your needs.

That is generally what I do (have done) however, in this case, I want to know what a semi-realistic number is since it is important in this specific case. I should clarify, the exact/specific/accurate "correct" number is not itself important, I just don't want the number of my choosing to be insanely off from what a formula might estimate (me saying a million when 10,000 is closer to the outcome of a formula, etc).

More specifically, I want to work out the starting (beginning) numbers so that they create my currently desired population, and so I have an idea of when such a thing needed to start (how long ago I should say) -- but this was just a long way of saying, "I need a population growth formula" hehe.



Thank again all, much appreciated - I think I have it all worked out now