Android DPI Calculator # Source: http://coh.io/adpi/

gistfile1.js

<script>
			$( function() {
				function applyToInputSet( id ) {
					var dpis = [ 320, 240, 160, 120, 212.8 ];
					var labels = [ 'xhdpi', 'hdpi', 'mdpi', 'ldpi', 'tvdpi' ];
					var inputs = $(id+' input');
					inputs.each( function(i) {
						if( this.value == '' ) {
							this.value = '';
						}
						set(this, this.value, dpis[i]);
					});
					
					function convert( source_value, source_dpi, target_dpi ) {
						// console.log( source_value, source_dpi, target_dpi );
						if( isNaN(source_value) )
							return '';
						
						return source_value * ( target_dpi / source_dpi ); 
					}
					
					function check( value, dpi ) {
						if (dpi == 212.8) {
							// console.log(Math.round(value / 1.33), convert(value, 212.8, 160));
							return Math.round(value / 1.33) == convert(value, 212.8, 160);
						}
						var l = dpi/40;
						if( (value % l) != 0 ) {
							// console.log(value, "not valid for", dpi, value / 1.33);
							return false;
						}
						return true;
					}
					
					function closest( value, dpi ) {
						var l = dpi/40;
						
						return Math.round(value / l) * l;
					}
					
					function set( input, value, dpi ) {
						input.value = value;
						$(input).data('last_value', value);
						// Find source input's label
						var source_hint = $(input).parent().find('.hint')[0];
						var source_hint_text = closest( value, dpi );
						if( source_hint_text != value && !isNaN(source_hint_text) ) {
							source_hint.innerHTML = source_hint_text;
						} else {
							source_hint.innerHTML = '';
						}
					}
					
					function onUpdate( dpi_index ) {
						
						var source_dpi = dpis[dpi_index];
						var source_input = inputs[dpi_index];
						
						if( $(source_input).data('last_value') == source_input.value ) {
							return;
						}
						set(source_input, source_input.value, source_dpi);
						
						var source_value = parseFloat(source_input.value);
						
						var source_hint_text = '';
						inputs.removeClass('error');
						if( source_input.value != '' && check( source_value, source_dpi ) === false ) {
							$(inputs[dpi_index]).addClass('error');
						}
						 
						
						var results = [ 0, 0, 0, 0, 0 ];
						inputs.each( function(i) {
							if( i != dpi_index ) {
								set(inputs[i], convert( source_value, source_dpi, dpis[i] ), dpis[i]);
							}
						});
					}
					
					inputs.each( function(i) {
						$(document.body).bind('keydown', function(e) {
							// console.log( e );
						});
						$(this).bind('keyup', function() { onUpdate(i); });
						$(this).bind('change', function() { onUpdate(i); });
					});
				}
				
				applyToInputSet( '#f1' );
				applyToInputSet( '#f2' );
			});
		</script>