Google is to offer free web measurement tools to advertisers to help them better target online audiences.

The announcement is expected from the web search giant today, and the service will compete with web measurement firms that offer similar paid-for information.

Google said that the more information advertisers have about audiences for their ads, the easier it is to target expenditure and generate better returns, benefiting both Google and the advertisers.

Other competitors in this market include comScore and Nielsen Media, which collect data in a different way to the new Google tool.

Google will collect data from web servers to provide insights into consumer behaviour online, while companies such as comScore and Nielsen Media gather information from sources that include surveys and customer panels.