Why 28-day prepaid phone plan recharges cost you more

If you browse mobile plans – and that’s not something you need to do every day, but it’s a wise thing to do at least twice a year to ensure that you’re getting the best value out of your mobile plan – you might have noticed that some “monthly” plans operate on a 28 day cycle, while others run to 30 days, and some are expressed simply as “monthly”.

Look, here’s a table of 28 day plans with at least 30GB of data to give you an idea of what I’m talking about:

You can probably work out that a 28 day recharge offers you slightly less time between recharges than a 30 day one without needing complex diagrams, but figure that if the cost is low (or at least acceptable) then the difference is marginal, right?

Wrong. Or at least, it could be problematic in terms of value if you stay on the same plan for a long period of time, which most of us do. Again, checking your plan value a couple of times a year is wise, but let’s say you’re going to stay on a given plan for a whole year.

First up, 28 day cycles are somewhat harder to calculate for when working out when you might need to recharge. If you’ve got automatic renewals in place, or you’re on a postpaid plan that rolls over, it’s pretty easy to miss that kind of timing, ending up stuck on a plan for an extra month, which can quickly become an entire year.

That’s where the sneaky part of a 28 day plan can really hit you. This does involve some maths, but it’s all pretty easy stuff and I promise you there isn’t a test at the end of it.

A typical year has 365 days, and many plans operate on a 30 day cycle, often called “monthly” even though the term of a month varies a little as you can confirm by staring at any calendar for even a few seconds.

In a typical year if you’re on a plan that refreshes every 30 days you’re up for 12 recharges to get you to 360 days, with five days left over for your next rollover period, but that will take you into the following year. Mathematically, 30 times 12 is 360. See, I said it was simple enough to follow!

Let’s give this some dollar value, but we’ll keep it simple and say that your telco only charges you $10 for each 30 day renewal. 12 recharges times $10 is $120 that you would spend on phone service over the vast majority of that year.

In that same typical year, you’d pay for 13 28 day recharges, because 28 times 12 is only 336, leaving a 29 day shortfall in the year – or in other words, an entire extra recharge that you’ll have to pay for.

That would take you through with just 1 day left in the year versus the five for the 30-day plan, but in either case you’re talking another recharge again to take you into the new year, and in any case, if the 28 day plan costs the same $10 fee, you’ve spent $130 on your phone service to cover you over most of that 12 month period.

Or in other words, telcos don’t choose 28 days because they just seriously love February, they do so in order to glean extra money out of customers each and every year.

While the use of 28 day plans can hide the quantity of recharges needed in a given year, the trick to getting the best value out of your phone plan is to break it down into a like-for-like comparison, and the easiest way to do that is to look at your daily cost.

To give this some numerical comparison, if you’re looking at a 30-day plan that costs $20 per 30 day cycle, that’s 20/30, or 66c/day.

If there’s a similar plan that has a 28 day recharge cycle for $15, that’s 15/30, or just 50c/day – better value.

But if the 28 day plan is $19 per recharge, while it might seem “cheaper” to your wallet in a single instance – and that’s true enough – you’re actually paying 67c (and nearly 68c if we round up) per day – worse value than the 30-day plan over time.

All of this assumes that the same plans have the same inclusions, which typically means the same quantity of data first and foremost; excluding PAYG plans you can safely assume unlimited standard national calls and texts are included in most plans.

You can weigh up your data needs separately depending on your usage, whether you’re a Disney Plus bingeing addict or a Tik Tok junkie, because there’s equally no point in paying extra for data if you’re not using it.

One detail to be careful of here is if you’re looking at and comparing long expiry plans, because most of these give you a six or twelve month expiry term.

That’s easy enough to work out the daily cost for, dividing either by 180 or 365 in most cases, but you need to be careful when considering your data inclusions.

Most long expiry plans come with a fixed quota of data to be used across the whole plan term, not a figure that’s renewed (or in some cases may bank) each month or even each 28 day cycle. Here’s a look at long expiry plans for comparison: