Mobile Data Plan Comparison Calculator

Why the cheapest headline price usually loses

Your mobile plan's headline price is marketing, not math. A $25 plan with a 15 GB cap looks cheaper than a $45 plan with 50 GB — until you burn through the cap and the overage meter starts ticking at four or five dollars for every extra gigabyte. Carriers count on you comparing sticker prices instead of real bills. The fair comparison is always: what will I actually pay each month, given how much data I really use? That number is almost never the one printed on the poster.

How this calculator works

Enter your real monthly data usage in gigabytes, then fill in two plans: monthly price, data allowance, and the per-gigabyte overage charge. The calculator adds base price plus overage — price + max(0, usage − allowance) × overage rate — to get each plan's true monthly bill at your usage, then divides by your usage to show the effective cost per gigabyte. The plan with the lower true bill wins, and the tool shows exactly how much you save per month and per year.

Worked example

Say you use 40 GB a month. Plan A costs $30 for 30 GB with a $5/GB overage: your bill is $30 + (40 − 30) × $5 = $80, which is $2.00 per GB. Plan B costs $45 for 50 GB with the same overage: your bill is $45 flat, or $1.13 per GB. Plan B wins by $35 a month — $420 a year — even though its headline price was higher. Now take a light user at 10 GB: Plan A at $25 for 15 GB costs $25 flat ($2.50/GB); Plan B at $20 for 10 GB costs $20 flat ($2.00/GB). Here Plan B wins on both sticker price and real cost. Same two plans, different winner — that is why usage is the input that matters.

Practical tips for picking the right plan

Check your actual usage in your phone's settings (look at the last three months) instead of guessing — most people overestimate or underestimate by a wide margin. If a plan is "unlimited", type a very large allowance such as 9999 GB so the calculator treats it as a flat rate. Add taxes and fees into the monthly price yourself so the comparison is apples to apples. And re-run the numbers whenever your habits change: a new commute with video streaming can flip the winner overnight, and the plan that was cheapest last year may be the expensive one now.