A few months after formally rolling out ads, Pinterest is giving marketers a better idea of how to spend their money on the social scrapbooking service.

Pinterest has updated its free analytics tool for businesses to offer new details about brands' audiences there, including where they live, what topics and other brands they're interested in and what level of traffic Pinterest is driving to their sites. That is the type of information that a marketer would want available when deciding how much of a brand's budget to dedicate to the social network.

Starting on Tuesday, any business across 31 languages can check out aggregated, anonymized information about their brands' Pinterest followings. Beyond data on audiences' interests and the other companies they follow, the new information includes gender, location and the devices people are using to pin sites' content.

"This new analytics tool for the first time is going to start to divulge profile-specific data," said Jason Costa, a Pinterest product manager for analytics and ad products. The company has never given parties such as retailers or publishers insights into how their accounts are performing, he added.

Pinterest's analytics update coincides with the expansion of marketers' ability to buy ads on the service. By opening up about marketers' Pinterest followings, the company is indirectly making a case for brands to put more effort -- and money -- into the site.

Last fall Pinterest said it would begin featuring ads and formally opened up the revenue stream in May. A month later the company added a self-serve ad-buying tool to make it easier for advertisers -- particularly small- and medium-sized ones -- to purchase the service's Promoted Pins. Only available to U.S. brands currently, Pinterest's ad product offers targeting options such as gender, language and device type that are similar to the new insights its analytics tool discloses.

Pinterest's new analytics tool stands to help businesses refine the audience they want to spend their money on and justify what a pin means in driving results. For example, a clothing retailer could see that its Pinterest following is really into camping and then post more pins of the brand's outdoor gear. That retailer could stop at posting the pins organically, but might also see that people are clicking on pins to reach the retailer's site and decide to pay to promote the pin for extra lift.

Mr. Costa said the analytics tool is primarily intended to help businesses manage their organic accounts by showing them what type of content performs well and what their audiences are interested in. But he acknowledged that it will have a carry-on effect with marketers' paid campaigns.

"A Promoted Pin is just an organic pin that the partner is paying to boost .... If they can get further insights into how their organic pins are doing, you could certainly imagine that informing their Promoted Pins campaign," he said.

Pinterest rolled out its first analytics tool in March 2013 as a means to drive adoption of its share button around the web. Aimed at site owners, the tool tracked stats related to its Pin It button, like how many people were clicking the button on a third-party site to post content to their individual Pinterest accounts.

Then in June the company began testing with roughly 100 U.S. companies a revamped tool that was more oriented around businesses' own Pinterest accounts. That test started with surfacing information like a brand's most popular pins, how many views their pins received and how many people pinned content from their sites. It evolved to include detailed audience insights, like interest and location segments down to the metro area for U.S. audiences. The tool also enables marketers to look at individual pins to see how many more impressions a pin that was promoted received compared to one that was not promoted.

The four-year-old company has raised $764 million in funding and counts 40.1 million monthly users in the U.S., according to eMarketer estimates.