Mobile Plan Comparison Calculator

Work out mobile plan comparison instantly with clear inputs, formula shown and shareable results.

About Mobile Plan Comparison Calculator

Comparing plans on headline price is misleading once usage exceeds the allowance, because overage is typically charged at several pounds per gigabyte. Adding the overage to the cheaper plan often reverses the answer entirely.

Formula

Plan comparison

effective cost = base cost + max(usage - allowance, 0) x overage rate

Worked example

With the default values below, Mobile Plan Comparison Calculator returns Better plan of Plan B is cheaper. Change any input above and every figure here is recalculated in your browser.

Inputs used

Plan A monthly cost: 18
Plan A data: 20 GB
Plan B monthly cost: 28
My monthly usage: 26 GB

Results

Better plan: Plan B is cheaper
Plan A cost including overage: $36.00
Plan A cost per GB used: $1.385
Annual difference: $96.00

Step by step

1Values used
2Plan comparison
3Better plan= Plan B is cheaper
4Plan A cost including overage= 36.00
5Plan A cost per GB used= 1.385
6Annual difference= 96.00

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax or compounding frequency into account.
Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Should I just buy the largest allowance?

Only if you use it. Most people buy 2-3 times the data they need, which is precisely what operators price for.

What about throttling instead of overage?

Some plans slow the connection rather than charge. That is usually better value, but check whether the reduced speed is usable for your needs.