This app was mentioned in 3 comments, with an average of 1.33 upvotes
Harvest seems to be pretty popular among freelancers but it has a monthly cost.
A free option may be Gekko Costs though annoyingly they have three seperate apps for costs, time and travel.
At my work we use Harvest, which is a service that tracks expences and time in this format (0.25 = 15 minutes, etc).
It's pretty neat once you get used to it.
Sounds like a freelance time tracking app would work? Along these lines:
https://play.google.com/store/apps/details?id=com.harvestapp