IDC estimates 47.6M tablets were shipped in Q3, +7% Q/Q and +36.7% Y/Y. The Y/Y growth rate represents a major slowdown from Q2's 60% (never mind Q1's 142%), and is below JPMorgan's forecast for 54% growth. It also puts IDC's September forecast for 227.4M 2013 shipments (+58% Y/Y) in doubt.
Apple (AAPL), which just reported 14.1M Sep. quarter iPad shipments, is assigned a 29.6% share, down from 40.2% a year earlier. In July, IDC gave Apple a 32.4% Q2 share, down all the way from 60.3% a year earlier.
A pending iPad refresh played a role in the decline - IDC expects "robust" iPad shipment growth in Q4 - but an industry mix shift towards cheap ~7" Android (GOOG) tablets (many of them from white-label OEMs) was also a major factor.
Samsung (SSNLF, SSNGY) is believed to have shipped 9.7M tablets, good for a 20.4% share (+800 bps Y/Y). IDC thinks Nexus 7 OEM Asus shipped 3.5M tablets and held a 7.4% share, and that Lenovo (LNVGY) shipped 2.3M tablets and held a 4.8% share.
IDC's numbers come two days after Strategy Analytics estimated smartphone shipments rose 45% Y/Y in Q3 to 251M. The two sets of figures suggest the smartphone market was 5.3x as large as the tablet market on a unit basis. That ratio will probably narrow in Q4, given the iPad refresh and the popularity of tablets as Christmas presents.