Texture format for 2D Android Game

Hello every one
I'm working on Android game that have a lot of objects with same shape & different text and color on them.

For now I'm using .png but I think the .png file is big!
After that issue I decide to use Shader that have { one alpha layer (all of objects have same Alpha) and a .jpg texture } but I get confused and don't know what is good for my Android game. TIFF , PNG , JPG or what?
Can you help me which format is good to have smal size and fast game?

 

If you do not need dynamic lights, go for (Mobile/Unlit (Supports Lightmap) standard shader. Textures 32x32 are the smallest size in Unity. As for best format it depends on what you need specifically. Start with low color-depth formats and increase color-depth if needed. See Unity answers or IndieBits.

 

really thanks @TechnoCraft My game haven't any light and I use unlit .
I get confused to use jpg with seperate alpha channel or a png , tiff , gif or ...
But your links helps me a lot.

 

png is your choice but you must know that In android the texture almost use the etc compression format, in gles2 the etc1 format is supported but etc1 has no alpha channel so in gles2 you need to split alpha in another texture, in gles3 devices, you can use etc2 which supports alpha channel so use 1 texture is ok but you must known etc is compressed,so there maybe some artifacts if you use them, like some banding in some gradient pattern.