Plan A
Plan B
| Plan A | Plan B |
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How to use the data plan cost calculator
The formula
Cost per GB = price ÷ included GB. True total = price + (usage − included GB, if positive) × overage per GB. Headline prices lie by omission — your usage figure is what makes the comparison honest.
Before you switch
Check contract length, mid-contract price rises (common in the UK), router/postage fees, and whether the headline speed is available at your address. This calculator handles the money; the small print is still on you.
Example
At 150 GB usage: Plan A (40 for 100 GB, 5/GB overage) really costs 40 + 50×5 = 290. Plan B (55 for 300 GB) costs 55. The 'expensive' plan saves 235 a month.
Frequently asked questions
Why does the cheaper plan sometimes lose?
Because of overage. A 40-unit plan with 100 GB looks cheaper than a 55-unit plan with 300 GB — until you use 150 GB and pay 5 per extra GB: the 'cheap' plan becomes 290. This tool prices plans at your usage, not at the headline.
How should I treat 'unlimited' plans?
Enter a very large included figure (we suggest 100000 GB) and 0 overage. But note fair-use policies: many 'unlimited' plans throttle speeds after a threshold — check the small print.
What if my plan slows down instead of charging overage?
Enter 0 as the overage charge. The plan then costs the same whatever you use — the trade-off is speed, not money.
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