Bootstrap 3 Media Queries for Breakpoints.

breakpoint.less

// Custom Iphone screen (MIN)
@screen-iphone-min: 320px !default;
// Extra small screen / phone (MIN)
@screen-xs-min: 480px !default;
// Small screen / tablet (MIN)
@screen-sm-min: 768px !default;
// Medium screen / desktop (MIN)
@screen-md-min: 992px !default;
// Large screen / wide desktop (MIN)
@screen-lg-min: 1200px !default;
// Extra small screen / phone (MAX)
@screen-xs-max: (@screen-sm-min - 1) !default;
// Small screen / tablet (MAX)
@screen-sm-max: (@screen-md-min - 1) !default;
// Medium screen / desktop (MAX)
@screen-md-max: (@screen-lg-min - 1) !default;



@media (max-width: @screen-xs-max) { ... }
/* Small devices (tablets, 768px and up) */
@media (min-width: @screen-sm-min) { ... }
@media (min-width: @screen-sm-min) and (max-width: @screen-sm-max) { ... }
/* Medium devices (desktops, 992px and up) */
@media (min-width: @screen-md-min) { ... }
@media (min-width: @screen-md-min) and (max-width: @screen-md-max) { ... }
/* Large devices (large desktops, 1200px and up) */
@media (min-width: @screen-lg-min) { ... }


/* Another Organization */

	/*  Mobile First Method */
	
    /* Custom, iPhone Retina */ 
	@media only screen and (min-width: @screen-iphone-min) { ... }
	/* Extra Small Devices, Phones */ 
	@media only screen and (min-width: @screen-xs-min) { ... }
	/* Small Devices, Tablets */
	@media only screen and (min-width : @screen-sm-min) { ... }
	/* Medium Devices, Desktops */
	@media only screen and (min-width : @screen-md-min) { ... }
	/* Large Devices, Wide Screens */
	@media only screen and (min-width : @screen-lg-min) { ... }

	/*  Non-Mobile First Method */

	/* Large Devices, Wide Screens */
	@media only screen and (max-width : @screen-lg-min) { ... }
	/* Medium Devices, Desktops */
	@media only screen and (max-width : @screen-md-min) { ... }
	/* Small Devices, Tablets */
	@media only screen and (max-width : @screen-sm-min) { ... }
	/* Extra Small Devices, Phones */ 
	@media only screen and (max-width : @screen-xs-min) { ... } 
	/* Custom, iPhone Retina */ 
	@media only screen and (max-width : @screen-iphone-min) { ... }

breakpoint.scss

// Custom Iphone screen (MIN)
$screen-iphone-min: 320px !default;
// Extra small screen / phone (MIN)
$screen-xs-min: 480px !default;
// Small screen / tablet (MIN)
$screen-sm-min: 768px !default;
// Medium screen / desktop (MIN)
$screen-md-min: 992px !default;
// Large screen / wide desktop (MIN)
$screen-lg-min: 1200px !default;
// Extra small screen / phone (MAX)
$screen-xs-max: ($screen-sm-min - 1) !default;
// Small screen / tablet (MAX)
$screen-sm-max: ($screen-md-min - 1) !default;
// Medium screen / desktop (MAX)
$screen-md-max: ($screen-lg-min - 1) !default;
 
 
 
@media (max-width: $screen-xs-max) { ... }
/* Small devices (tablets, 768px and up) */
@media (min-width: $screen-sm-min) { ... }
@media (min-width: $screen-sm-min) and (max-width: $screen-sm-max) { ... }
/* Medium devices (desktops, 992px and up) */
@media (min-width: $screen-md-min) { ... }
@media (min-width: $screen-md-min) and (max-width: $screen-md-max) { ... }
/* Large devices (large desktops, 1200px and up) */
@media (min-width: $screen-lg-min) { ... }
 
 
/* Another Organization */
 
    /*  Mobile First Method */
    
    /* Custom, iPhone Retina */ 
    @media only screen and (min-width: $screen-iphone-min) { ... }
    /* Extra Small Devices, Phones */ 
    @media only screen and (min-width: $screen-xs-min) { ... }
    /* Small Devices, Tablets */
    @media only screen and (min-width : $screen-sm-min) { ... }
    /* Medium Devices, Desktops */
    @media only screen and (min-width : $screen-md-min) { ... }
    /* Large Devices, Wide Screens */
    @media only screen and (min-width : $screen-lg-min) { ... }
 
    /*  Non-Mobile First Method */
 
    /* Large Devices, Wide Screens */
    @media only screen and (max-width : $screen-lg-min) { ... }
    /* Medium Devices, Desktops */
    @media only screen and (max-width : $screen-md-min) { ... }
    /* Small Devices, Tablets */
    @media only screen and (max-width : $screen-sm-min) { ... }
    /* Extra Small Devices, Phones */ 
    @media only screen and (max-width : $screen-xs-min) { ... } 
    /* Custom, iPhone Retina */ 
    @media only screen and (max-width : $screen-iphone-min) { ... }