The National Retail Federation projects that U.S. nonstore holiday sales this season could increase 11%-15% year over year, to about $136.42 billion to $141.34 billion. Nonstore sales are mostly online purchases but also include sales via phone and catalog.

For the 2016 holiday season, which the NRF defines as retail sales in November and December, nonstore sales increased 12.6% to $122.9 billion, beating the NRF’s estimate of 7%-10% growth.

For total holiday sales in 2017, NRF estimates a 3.6%-4.0% increase over last holiday season. Sales figures are projected to reach $678.75 to $682.0 billion, up from $655.8 billion last year. Numbers are rounded.

NRF attributes the increase in holiday sales, both in stores and online, to several factors, including strong consumer confidence, job growth, and higher income and wages, says NRF chief economist Jack Kleinhenz.

Plus, time is on retailers’ side this year. There is an extra day between Thanksgiving and

Christmas this year, 32 days, compared with 31 last year, and that gives consumers an extra day to shop. What’s more, Christmas falls on a Monday this year compared with Sunday last year, giving shoppers an extra weekend day to shop.

“That extra day and that extra weekend will be meaningful,” NRF president and CEO Matthew Shay said on a call announcing the forecast.

These projections are similar to other market research firms’ estimates.