Michal Smetana · Updated 03/10/2026

Browser bookmarklet: a listing into the calculator in one click

Drag the Výnosometr button to your bookmarks bar. On a Czech property listing (Sreality, Bezrealitky, iDNES Reality and others) click it and the calculator fills itself in. The text stays in your browser.

The bookmarklet takes the text of the open listing and opens Výnosometr with the price, floor area, city, HOA fees and more filled in. You see a summary of what was taken, warnings (for example cooperative ownership or energy class G) and you can undo the import with one button.

How to add it (3 steps)

1. Show the bookmarks bar: Ctrl+Shift+B (Windows, Linux) or Cmd+Shift+B (Mac).
2. Drag the button below to the bookmarks bar with your mouse, do not click it.

   To Výnosometr

3. Open a listing and click the To Výnosometr bookmark. The calculator opens in a new tab with the values filled in.

If you click the button here by mistake, it only reminds you to drag it.

Supported portals

Sreality, Bezrealitky, iDNES Reality, RealityMix, RE/MAX, Century 21, Reality.cz, UlovDomov and generally any Czech-language listing page. The bookmarklet only reads the text you can see; if the portal hides details (for example price on request), the calculator tells you.

Privacy

The bookmarklet passes the title, address and at most 6,000 characters of page text in the part of the address after the # sign (vynosometr.cz/en/#import=...). Browsers do not send this part to the server, processing happens only in your browser and the calculator clears the address as soon as it loads. We only count how many values were recognised, never the listing content.

On mobile

Mobile browsers make adding such bookmarks difficult. On a phone, open the listing, select and copy the text and use Paste a listing in the calculator.

Bookmarklet code

If dragging does not work, create a bookmark manually and paste this code as its address:

javascript:(function(){try{if(location.hostname==="vynosometr.cz"){alert("Výnosometr: drag this button to your bookmarks bar and use it on a listing page.");return}var m=document.querySelector('main,[role=main],article'),b=document.body;var x=((m&&m.innerText&&m.innerText.length>400?m.innerText:b&&b.innerText)||'').replace(/[ \t\u00a0]+/g,' ').replace(/\n\s*\n+/g,'\n').trim().slice(0,6000);var s=JSON.stringify({v:1,u:location.href,t:document.title,x:x});var e=btoa(unescape(encodeURIComponent(s))).replace(/\+/g,'-').replace(/\//g,'_').replace(/=+$/,'');var u="https://vynosometr.cz/en/#import="+e;var w=window.open(u,'_blank');if(!w)location.href=u;}catch(err){alert("Výnosometr: could not read the page text. Please copy it manually.")}})();