Business mobility provider iPass has launched a mobility expense "calculator", in a bid to convince users to see their costs, grasp the nettle, and subscribe to iPass.

Mobile data costs are hard to evaluate as workers often buy hourly or daily Wi-Fi vouchers, which are charged back in expense accounts and never appear on the communications budget. Up to 70 percent of broadband expenses can be hidden in this "black budget" according to Gartner Research, but iPass reckons it can expose it: "Organisations are given visibility of their total wireless connectivity cost and gain insight into hidden wireless connectivity expenses," it promises.

However, this is an online tool, relying on user input, so it can't actually reveal anything hidden. The Mobility Expense Calculator is more of an estimator.

Users enter basic details of their company - the name, number of employees and where it is located. Then they guess the percentage of users who are mobile, as well as dividing workers between four broad segments - frequent and infrequent, intercity and local travellers - and guess the percentage who have 3G and Wi-Fi hotspot subscriptions. To help them along, iPass offers suggestions - ten percent of mobile employees have 3G subscriptions and ten percent have Wi-Fi subs, for instance.

The calculator then applies black magic based on iPass' "in-depth understanding of mobile usage patterns" including differing user types and prices across different geographies, to come up with a figure. .

We were surprised how little the price varied between US and Europe - following iPass' suggestions and mobilising 50 percent of a 100-strong company, we wound up with costs of $64.35 per month for a US company, and $66.09 for a European one. Both figures are in US dollars, and - though it is very hard to get iPass to quote a definite figure for its own flat rate monthly service - it's interesting that these figures are higher than the $40 a month which we understand is a typical price for an iPass subscription.

The calculator is part of a Mobility Central site which also includes a hotspot finder and an index of Wi-Fi usage within iPass customers.

The site will be useful for any IT managers who already knows they want to centralise mobile spending and gain control by moving the company onto iPass, where users pay a flat monthly rate that is billed centrally, and use an access client that is managed centrally. However, anyone assessing such a move would have to question the bias of the source.

"Organisations need to get a handle on their remote and mobile connectivity costs without creating a cost management nightmare and missing out on the strategic business benefits mobility can deliver," said Eric Paulak, managing vice president at Gartner Research.