Guesstimate 1 – How many t-shirts are sold in India per day?

How many t-shirts e-commerce companies selling in India per day?
We can approach this problem in two ways:
Demand side
Supply side
I am going to solve using demand of t-shirts in the market

Total population of india : 1 bn (approx)
Reach to internet : 40% =400 Mn
Reach of ecommerce companies to deliver products : 3/4th = 300Mn
Let’s assume 50% are male and 50% are female

Lets solve for male population first:
Now i have divided males in the four categories on the basis of age because demand of t-shirts for different age groups will be different
0–15 yr = 45 Mn, on an average, individual own 4 t shirts -> 445=180 Mn 16–22 yr = 23 Mn, on an average individual own 4 t shirts -> 423 = 92 Mn
23–50 yr = 65 Mn, on an average individual own 3 t shirts -> 365 = 195 Mn 50 – 80 yr = 18 Mn, on an average individual have 2 t shirts -> 218 = 36 Mn

Total t shirts own by men : 180 + 92+195+36 = 503 Mn ~ 500 Mn

Let’s solve for female population now:
0–15 yr = 45 Mn, on an average individual own 2 t shirts -> 245=90 Mn 16–22 yr = 23 Mn, on an average individual own 4 t shirts -> 423 = 92 Mn
23–30 yr = 15 Mn, on an average individual own 3 t shirts -> 3*15 = 45 Mn
30 – 80 yr = 67 Mn -> we can neglect this section. Only few ladies prefer to use t-shirts in this age group.

Total t shirts own by females : 90+92+45 = 227 Mn ~ 230 Mn

Total t shirts own by men + women = 500+230=730 Mn
Average life of a t shirt = 2 year
Demand per year = 365 Mn ~ 360 Mn
Online portals provide coupons and offers but because of trust factor and fitting issues, people in india still prefer to buy offline, So i am assuming 30% of people buy t shirt from ecommerce portal and 70% are buying from market.

Total number of t-shirts sold through ecommerce platform per year in India= .3*360 = 108 Mn ~ 100 Mn per year

Number of t-shirts sold in India per day(From ecommerce portal) = 100 * 10^6/365 ~ 27,000