@deathshadowJun 17.2014 — #Resize your browser window making it smaller and smaller -- if the layout changes the number of columns or otherwise re-arranges itself, it's responsive.
That's what responsive layouts do -- they change themselves to fit the available screen space; which is why fluid layout is one of the 'stepping stones' to making an accessible responsive design as you're already 'halfway there'.
You can also look at the CSS and see if it contains "@media" -- so called "media queries" are what makes responsive layouts work.
@omthavertchJun 20.2014 — #yes true resize your window size and check the site look great or not if it is look nice then site is responsive else you have to work on it to make it responsive
@nada_book14Jun 21.2014 — #That is not the Big deal to check responsive or not. You can check this quality of website by resizing the browser and also with passing the input to the website.
@MukeshKrJun 24.2014 — #Open your website in several devices like desktop, laptop, mobile phones, tablets and i-pads. If the site adjust it self according to the window site than the site is responsive otherwise not.