Small app (around 10 screens)

Strategy - 2 to 5 days (depends on time spent discussing and brainstorming with our client)

Low / High fidelity wireframe design - 1 week

Actual app design - 2 weeks (after the wireframe is fixed)

I will deliver all assets and I will give support for development team as well.

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Complex app (around 20 or more screens)

In such cases it is difficult to estimate a time frame. It depends on the complexity and the scope the app has to offer. Also it takes more time to make strategy for more detailed software. Still one can get an idea from the estimate I share for smaller apps.