Estimation means rough calculation of the value, number ,quantity OR extent / addition of something. But, it should not be that much of rough that cost or efforts will reach to 2 times or sometimes 3 times than actual calculation.
It’s always hard to make exact estimation of any Mobile application or any software product. Even if you’re starting to make furniture of your Home, then also you will get more than 20% variance without adding any new item. (Personal Experience)
I want an estimation on the size of a room but I will only let you look through the keyhole.” – The new trend in Software Programming
It would be always difficult to identify that whether we should provide estimation with amount of requirement we’re having or not. There is not any specific percentage defined like you can give estimation with 70% requirement or 50 % requirement. In some cases, if you’re having 90% requirement clear but remaining 10% can make your efforts double. While in some cases you can make profit with 40%-50% clear requirement. It totally depends on your way of looking into system and of course your past experience.
Normally, we’re providing estimation with considering medium level Engineer OR sometimes considering Expert level if we’re getting good Cost OR long term client relationship.
Features Listing :
Whatever you understand from given requirements, please don’t forget to mention in your estimation sheet. Don’t make assumption. Assumption is crime while making estimation. But, for uncleaer requirement, if you’re making assumptions then don’t forget to mention…!!!
Supported Device and OS :
Never forget to include support environment of your application. Please mention all supported devices and of course OS also. It’s mandatory to mention app for Smartphone only or Universal as we’re living in era of Tablets. Don’t assume that client is educated and understand that Smartphone app will not work in Tablet. (with different UI otherwise in case of iOS, iPhone app can be installed on iPad)
Application Orientation :
Do mention application mode also like application will work in Portrait mode or Landscape mode or both. In my earlier days of development, we had misunderstanding on application mode and it cost additional 400 hours to my company. So, never forget it. You never know if you forget this one line then what would be cost of it. Sometimes, you may buy new Home or Car with that additional cost.
Offline Mode :
In case of Mobile application, it’s necessary to include that whether your application will work without internet connection or not. So, please confirm that application will work stand-alone or not.
Cloud Infrastructure :
You need to add infrastructure cost also in case if application require  cloud infrastructure.
3rd Party Integration :
If client wants to integrate any 3rd Party SDK, then please add cost of it as per userbase of application with limitations of platform. Because, you can’t do any major change in 3rd party library and definitely can’t develop it on later stage. As per rule of Software engineering, don’t waste time to develop something which is already developed and available on Google free.