Apple's first foray into the world of the smartwatch generated nearly 1 million pre-orders in the United States on Friday, according to early estimates by the research firm Slice Intelligence.

Using e-receipt data, the company said that 957,000 people in the U.S. placed orders for an Apple Watch on the first day it became available.

The hotly-anticipated watch sold out online within hours. Buyers of some models won't receive their devices until May, while others will have to wait until July.

Slice Intelligence looked at sample data from 9,080 online shoppers, and said each Apple Watch buyer ordered an average of 1.3 watches and spent an average of $503.83 per device.

High-end luxury audience

Unlike many Apple product launches, there were no fans queuing around the block Friday because the devices were only available for pre-order online.

Apple touted the design of the Watch at its launch in March and the devices have a number of interchangeable bands. The global launch means people in Australia, Canada, China, France, Germany, Hong Kong, Japan, the U.K. and the U.S, can now pre-order a device.

In an attempt to create exclusivity and capture a high-end, luxury audience, Apple has even released an 18-karat gold version known as the Edition which starts at $10,000. The Apple Watch Sport starts at $349, while the Apple Watch starts at $549.

Slice Intelligence said that U.S. customers spent an average of $382.83 on the Apple Watch Sport and $707.04 on the Apple Watch.

This is Apple's first foray into wearable technology, despite many competitors such as Samsung and Motorola already releasing several smartwatches.