From what I have seen, it completely depends on the subject matter you are consulting on .... For example, I charge by the week (I can charge by the hour if I want, but I don't want to go through the process of tracking the hours etc) and I consult MNCs like Unilever,Linfox Logistics etc on Business Process Re-Engineering & Automation and for that I charge them 1L to 50K per week depending on the project [I audit and document existing processes and systems and estimate how much money and time they can save will improving or retaining the accuracy (or some similar metric)]... so I have to wear multiple hats in the project such as software architect, project manager, developer etc... so in the weeks I have to come up with the design for the system as an architect I charge them 1L and while I develop the system & manage my dev team I charge 50k and if they need some thing simple (like building some macros) , I send one of my developers to work with them and charge them ~25k. And just like normal gigs your expertise and track record has quite a bit of impact on what you can charge them.