It does depend on several factors, but if you make some reasonable assumptions the answer can be much more useful.
For on-screen presentation it isn't helpful to talk about DPI figures - you want an actual number pixels. An image of 10 pixels by 10 pixels can be printed at any DPI you like (you'll see the individual pixels but it will print), but on screen it is 10 pixels by 10 pixels.
The 60x60 logo is only 4kb. A typical 70kb photograph (as a JPEG with medium compression) would be around very roughly 600x400 pixels.