Disclaimer- I am seeking advice to give my over 18 year old DD a couple of ideas, please do not waste your time to say that over 18 year olds should not seek advice from their parents- I have already read lots of those comments on other threads 
DD has just finished year 1 at a London uni and will be living with 3 other girls next year. They have found a reasonable house and are about to sign the contract and move in within the next couple of weeks. The contract will be joint and several and states only the full amount of rent due per month (over £3000- be warned prospective parents of London students) and they are trying, and failing, to agree fair rents for each room.
Three bedrooms are upstairs - two large, one medium (say 100%, 100%, 77% floor area). The final bedroom is on the ground floor- the smallest (51% area) and there is not enough room to fit the desk against the wall, it has to be in front of a built in wardrobe.
Does anyone have any tips as to how to price rooms? DD is the most budget- challenged and when house-hunting had been happy to take the smallest room to keep the price down , but cannot currently get the others to agree a price differential of more than 7% of the rent between biggest and smallest which would just not be not be worth it for a year of taking the worst room.
They need to sign and move in and are now saying that they want to all pay equal for the first month's advance rent and sort it out after they move in- DD is the lead tenant so will have to get rent off the others every month before paying the landlord so wants it all agreed before they sign.
I don't remember all this stress when I rented a gazillion years ago!
How do landlords price different rooms?