Calculating efficiency - what website do you prefer

I had been using Rooftopbrewing brewhouse efficiency calculator in the past and really liked it, but it seems to have disappeared from the site.

Are there any online calculators that you guys like to use for this? I've tried a few others and none of the ones I found weren't as easy to use as rooftops.

Thanks!

Brewersfriend.com has a good one.

Anymore I just use the average ppg of the malts or grains I use most, and calculate. I don't really care about efficiency, just that I don't short the grain bill.
Brewzor pro or iBrewmaster are good phone apps. I use them in reverse. Enter grain bill and volume, then adjust the efficiency setting until the calculated og matches measured.

Thanks Pelipen.

Yeah I always always always use: http://www.brewersfriend.com/brewhouse-efficiency/

At Brewer's Friend you can also setup a recipe and adjust the efficiency to see the effect on OG. Or, you can 'brew' the recipe, then enter brew day logs and it will compute four types of efficiency: conversion, pre-boil, kettle, and brewhouse. We have robust definitions for 'batch size', and 'efficiency', since there is too much conflicting stuff floating around out there.

Here is a post by Kaiser at that provides complete details and a nice diagram:
http://www.brewersfriend.com/2012/11/30/making-sense-of-efficiency-definitions/