Although Apple, Amazon and Google do not release Nexus 7 or iPad mini sales figures, there are those who estimate sales figures by using logic, quotes and other sources.
An analyst, Benedict Evans, has crunched some numbers to compare sales figures.
Asus makes the Nexus 7 and does disclose tablet sales. Evans noted that verbal comments indicate 2.1-2.2millin Nexus 7 sold in Q3. He calculated Nexus 7 sales of 4.5 to 4.6 million and no more than 4.8 million.
There were shortages of the Nexus 7 went it first went on sale. The Nexus 4 and 7 were recently updated to Android 4.2.2 Jelly Bean. The Nexus 4 is usually hard to find with waiting times for delivery in weeks.
Amazon does not announce Kindle Fire HD sales however, due to holiday sales Evans assumes that more Kindle Fire HD were sold than Nexus 7 tablets.
He estimated that Apple sold 10million iPad mini tablets. Therefore, although Nexus 7 sales have been great, they don't beat the Apple empire. The iPad mini was introduced in the fall of 2012. Read review and compare it to Nexus 7 and Kindle Fire HD. Compare Kindle Fire to iPad mini.
Currently Amazon is running commercials comparing the the Kindle Fire HD 8.9 to the iPad, mainly pointing out the huge price differences.
Meanwhile forum members by sharing IMEI numbers have calculated that over one million Nexus 4 have been sold.