Google's Same-Day Delivery Service Undercuts Amazon Prime by $4 The Mountain View, Calif.-based tech goliath is expanding its same-day delivery program and starting to charge for it.

Google has stepped into the ring with Amazon to battle it out over delivery.

Today, Google announced that it would be expanding its same-day delivery service -- and begin charging for it.

Google Express, which was called Google Shopping Express before today, gives members unlimited same-day or overnight delivery on orders over $15. The service only applies to products from participating retailers. Membership costs $95 a year, or $10 a month.

The $95 membership comes in just under Amazon's $99-a-year service, Amazon Prime, which offers free two-day shipping and subscription to streaming content and e-books in Amazon's Kindle Owners' Lending Library.

Related: Price of Amazon Prime Jumps to $99

Google Express launched in beta in San Francisco in March of last year. At the end of September, it was made available to all San Francisco area residents with the option of a six-month free trial period. In May, Google extended the service to New York City and parts of Los Angeles with the same introductory offer.

As of today, the Google Express service is expanding to Chicago, Boston, and Washington, D.C. Also, Google has added 16 retailers to the list of approved stores that customers can order from as part of the service. Those new merchants include 1-800-Flowers, Barnes & Noble, Nine West, PetSmart and Vitamin Shoppe.

Related: UPS Ups Its Shipping Game

Orders are either fulfilled in the same day, in a window that the customer chooses, or in some cases, the next day. New customers are eligible for a free three-month trial period.

For delivery of orders under $15, Google Express charges members $3. Nonmembers can pay $4.99 for same-day delivery of any order over $15, and $7.99 for any order under $15.

Related: To Beat Ecommerce Rivals, Know Your Shipping Options