How many iPads are sold in the USA every year?

Clarifying questions:
Personal or business? personal
New/refurbished/used? New

US population is ~300m

Analysis:
Demographic -

• Age let's assume equal brackets of age and exclude kids under 8 and adults above 70 since it is less common on those groups in a span of 0-80 its - ~%25 (a little less 22.5 but lets simplify fo the answer) So around -70m : 230m
• Economic class since iPad is a pricy high-end product I can assume it is more common across middle and upper-class
  let's estimate lower&upper 25% each, and middle is 50%
  so another -25%-around -58m(lets round to -60m) : 170M

• Advocate Buys every single model that goes out, owns multiple/all Apple products, will buy every 2y
• Fan loves apple, owns an ipad/iphone/apple tv, will buy every 2-3 releases, so lets assume every 5y
• Kids (age 7-17) will get an iPad from their parents when they get to the right age (1 per kid no rebuy)
• Students will use for class activities, and get as present when starting college (1 per student no rebuy)
• Upgrader moved from a competitor tablet and upgrading to an iPad (1 per upgrader no rebuy)

Market penetration 
Since Apple iPad has some competitors from Google, Samsung etc, I can assume their market penetration in the US is around 60% share of the tablet market.

Tablet is less common product than Smartphone so let's assume that around 40% of the eligible(170M) population owns a tablet
so lets say around 70m

apple with 60% market share - let's simplify 40m total.

Now lets divide via the personas buying habbits

• Advocate let's assume 10% of the group, buys 0.5/y so 4Mx.5-2M/y
• Fan -lets assume its the bigger group with 50% of the 40M that buys 0.25/y- so 20Mx.25= 5M/y
• Kids-there are around 20% kids population, lets say 10% is eligible age(7-17) group, so 4M, divided by years with an even spread so 4M/10y= 400,000/y(lets simplify to .5M/y)
• Students- lets assume 5% of the population in the US are collage students, so 2M from the group, divided by the average nm of years per degree(4) since each student buy once gives us .5M/y
• Upgrader- lets assume 20% of our group upgrading from a different tablet, buying once(then churning or added to one of the other group personas 8Mx avarage lifespan of a tablet lets say 5y
  so 8M/5y= around 1.5M/y
   

Clarifying questions

-          We are talking about the first hand purchase à right

Top down approach

-          Total population of USA = 300 mn

-          Let’s take the life-expectancy at 80, distributed uniformly

User segment – purchase Ipad

-          Personal usage

o   Entertainment

o   School/college student

-          Official purpose

Ipad is a tab category and considering USA is a developed country, I assume

-          Ipad – 50%

-          Android tab – 40%

-          Others – 10%

New purchase would be related to 2 factors

a. First hand purchase

b. upgrade to newer version

Total household would be 100 million assuming avg. 3 members in family

-          Distribution of Income groups – Penetration of Tabs

-          Low – 20% | Middle – 40% | High

-          Low – 20% -- 0% penetration | Middle – 60% - 40% penetration | High – 20% - 80% penetration

-          Market size for Tab

o   Low - 20% X 0% = 0

o   Middle – 60% X 40% X 100 mn household = 24 mn households X 50% = 12 mn for Ipad X Avg 1 Ipad per household = 24 mn

Replace every 5 year = 24/5 = 4.8 mn new Ipad per year

o   High - 20% X 80% X 100 mn household = 16 mn household X 50% = 8 mn for Ipad X 2 Ipad per household = 16 mn

Replace every 2 year = 16/2 = 8 mn new Ipad per year

12.8 mn Ipad sold per year in USA