And 55.2m expected by the close of 2011.
UK-based analyst firm Juniper Research is forecasting that tablet shipments will hit 253 million by 2016, almost five times the number expected this year.
The tablet market is becoming increasingly busy with Apple's iPad 2 leading the way, while Samsung, HTC, Sony, RIM and many more are also producing devices.
Currently, shipments of tablets with cellular connectivity are much lower than those with only wi-fi network access, but over 50 per cent of annual tablet shipments will have cellular connections by 2016, according to the report.
Daniel Ashdown, report author, said a critical driver of the market will be the adoption of single tariffs for phone and tablet.
He said: "Multi-device plans [for a smartphone and a tablet] will overcome the problem of consumers not wanting to pay another subscription", as he speaks of the retail strategy in place."
Juniper also claims that as the PC market slows down, companies including Acer, Dell, HP and Toshiba will be join the rapidly-growing tablet market.