This spring, millions of mobile phone users in Britain will face higher bills due to unexpected mid-contract price hikes.

The extent of the price increase that customers will encounter in March or April will depend on their mobile phone provider as well as the timing of when they signed their contract.

Customers on older contacts will likely see bills rise based on yesterday's Consumer Prices Index inflation figure of 2.5 per cent, plus an additional arbitrary 3.9 per cent.

Nonetheless, newer clients are more likely to experience a price hike by a specific sum, detailed in pounds and pence, as stipulated in their initial agreement.

Now, you can find out how much extra you will have to pay with MailOnline's online calculator, brought to you by household money-saving tool Nous.co.

Simply enter your current mobile phone bill and provider in the widget to find out what the hike in a few months' time is expected to cost you. 

New Ofcom rules demanding mobile firms provide more clarity on bills come into force tomorrow - although some providers have already introduced these changes.

However, the modification in the regulations indicates that certain customers on lower-priced plans will experience price increases that exceed what they would have faced under the old system.

For example, a Vodafone customer paying £25 a month will see their bills rise by a flat rate £1.80 per month according to the new rules.

Under the old system their bill would rise by yesterday's CPI figure of 2.5 per cent plus 3.9 per cent - an increase of £1.60 a month.

Britons who signed a contract prior to their provider adopting the new Ofcom regulations should anticipate that their price increase this spring will be tied to the inflation rate released this week.

Greg Marsh, the CEO of Nous, expressed to MailOnline: 'Telecom companies are once again burdening consumers with unjust and exploitative price hikes.'

The new Ofcom regulations coming into effect this month will require suppliers to provide clearer information regarding the costs associated with price increases for their loyal customers. However, it's important to note that these rules do not extend to existing contracts.

"For those on budget plans, their costs are set to rise even more than they did with the previous system. This is obviously unjust. Dealing with this complicated and deceptive pricing structure is both challenging and tedious. It's no surprise that many of us overlook these issues."

'This is the reason we launched Nous. We help families save both time and money by taking care of their bills on their behalf.'