var cols = $(".container .item").length;
if (cols == 5){
    $('div.item').removeClass('col-md-2..etc').addClass('col-md-3').css('width', '20%');
 }

Jquery和完成!框架!

引导4，每行可变列数

如果你想每行最多有5列，这样每一行的列数仍然只占一行的1/5，解决方案是使用Bootstrap 4的mixins:

SCSS:

.col-2-4 {
    @include make-col-ready(); // apply standard column margins, padding, etc.
    @include make-col(2.4); // 12/5 = 2.4
}
.col-sm-2-4 {
    @include make-col-ready();
    @include media-breakpoint-up(sm) {
        @include make-col(2.4);
    }
}
.col-md-2-4 {
    @include make-col-ready();
    @include media-breakpoint-up(md) {
        @include make-col(2.4);
    }
}
.col-lg-2-4 {
    @include make-col-ready();
    @include media-breakpoint-up(lg) {
        @include make-col(2.4);
    }
}
.col-xl-2-4 {
    @include make-col-ready();
    @include media-breakpoint-up(xl) {
        @include make-col(2.4);
    }
}

HTML:

<div class="container">    
  <div class="row">
    <div class="col-12 col-sm-2-4">1 of 5</div>
    <div class="col-12 col-sm-2-4">2 of 5</div>
    <div class="col-12 col-sm-2-4">3 of 5</div>
    <div class="col-12 col-sm-2-4">4 of 5</div>
    <div class="col-12 col-sm-2-4">5 of 5</div>
  </div>
  <div class="row">
    <div class="col-12 col-sm-2-4">1 of 2</div> <!-- same width as column "1 of 5" above -->
    <div class="col-12 col-sm-2-4">2 of 2</div> <!-- same width as column "2 of 5" above -->
  </div>
</div>

在Bootstrap 3中启用5列的另一种方法是修改Bootstrap默认使用的12列格式。然后创建一个20列的网格(在Bootstrap网站上使用自定义或使用LESS/SASS版本)。

要在引导网站上进行自定义，请访问自定义和下载页面，将变量@grid-columns从12更新为20。然后，您将能够创建4以及5列。

在我看来，像这样使用Less语法更好。 这个答案是基于@fizzix的回答

这样列使用用户可能覆盖的变量(@grid-gutter-width, media breakpoints)， 5列的行为与12列网格的行为匹配。

/*
 * Special grid for ten columns, 
 * using its own scope 
 * so it does not interfere with the rest of the code
 */

& {
    @import (multiple) "../bootstrap-3.2.0/less/variables.less";
    @grid-columns: 5;
    @import  (multiple) "../bootstrap-3.2.0/less/mixins.less";

    @column: 1;
    .col-xs-5ths {
        .make-xs-column(@column);
    }

    .col-sm-5ths {
        .make-sm-column(@column);
    }

    .col-md-5ths {
        .make-md-column(@column);
    }

    .col-lg-5ths {
        .make-lg-column(@column);
    }
}

/***************************************/
/* Using default bootstrap now
/***************************************/

@import  (multiple) "../bootstrap-3.2.0/less/variables.less";
@import  (multiple) "../bootstrap-3.2.0/less/mixins.less";

/* ... your normal less definitions */

对于@lightswitch的回答，如果我们需要使用更少迭代的5列网格

.make-fifth-col(@index) when (@index > 0) {
  @class-name: ~".col-md-5th-@{index}";

  @{class-name} {
    .make-md-column(1.2*@index);
  }

  .make-fifth-col(@index - 1);
}

.make-fifth-col(10);

这将生成css类。col-md-5th-1, col-md-5th-2, col-md-5th-3，等等，对应10%，20%，30%…分别

5列布局与Twitter引导风格

.col-xs-15 {
    position: relative;
    min-height: 1px;
    padding-right: 10px;
    padding-left: 10px;
}

.col-xs-15 {
    width: 100%;
    float: left;
}
@media (min-width: 768px) {
.col-xs-15 {
        width: 50%;
        float: left;
    }
}
@media (min-width: 992px) {
    .col-xs-15 {
        width: 20%;
        float: left;
    }
}
@media (min-width: 1200px) {
    .col-xs-15 {
        width: 20%;
        float: left;
    }
}