If all the ice melts in the world, how much land will be left?

So, there are a few pieces to this: 

1. First an important premise: Only ice that currently sits on land would contribute to increasing sea levels. Sea ice, which forms by freezing of sea water at high latitudes, does not change sea level. So to answer your question we must look at land ice alone. 
2. What counts as land ice, and how much sea level does it correspond to? Land ice is found in (i) the grounded parts of the two major ice sheets on Earth, Greenland and Antarctica, (ii) a few smaller ice caps (like Svalbard), and (iii) mountain glaciers. If the Greenland Ice Sheet melted, scientists estimate that sea level would rise about 6 meters. If the Antarctic Ice Sheet melted, sea level would rise by about 60 meters. If all the mountain glaciers on Earth melted, sea level would rise by about 40 cm. In total, this adds up to approx 66.4 m. 
3. How much land would be left if all this land ice melted? Well, all the land that is approx. 65 m above sea level nowadays. You can go check on Google Earth or similar what that means for the place where you live.  Can you find out what would be above this level? When you do this, just bear in mind that even if all this ice were to melt (which we do not know it will), certainly it would not happen in our lifetime, and most likely for several centuries. What’s important to realize though is that the impact this could have is huge for all people living on Earth, so we should do all we possibly can to avoid making climate warmer and our land ice melt.