Hi,
You can calculate it from the demand and supply sides:
Demand side:
- Population of London
- % of the population that orders food on demand (use the sample of your friends and family)
- Frequency - How many times per month do an average person order food on demand (Again I will use a personal example taking a sample of my friends and relatives. The main tip here - take the weighted average. Remember that only a small share of users is frequent (more than 4 orders per month) but the average user will probably order once in a month.
- Deliveroo market share - ask the interview, or make an assumption (e.g. out of 10 couriers I see in the street 7 are Deliveroo)
- Total Deliveroo orders per month = Population * % use on demand * Frequency
- Assume the number of orders an average driver is making per month (20 working days * 8 hours per day * 3.5 orders per hour (taking into account that utilization is not 100% and that a driver is carrying more than one order))
- Number of monthly active drivers = Total orders per month / monthly orders per driver
Supply side / sanity check:
- When I open the Deliveroo app I see xx couries covering some area (at least it works for Uber)
- Assume some utilization rate for peak / off-peak and apply it to get the total number of cars in your area
- Multiply that area by the number of similar areas to cover the city (adjust to how busy your area is)
Best!
5 sessions package with Vlad 
