What is the Data Cap Overage Calculator?
Many internet and mobile plans include a monthly data cap. Use more than your allowance and the provider often bills an "overage" fee for each extra gigabyte. This calculator tells you whether you've crossed your cap, how much data you went over by, and what the extra charge will cost — so there are no surprises on your bill.
How to use it
Enter three numbers: the data you've used so far (in GB), your plan's data cap (in GB), and the price your provider charges per extra GB. The calculator shows your estimated overage cost, the gigabytes over the limit, how much data you have left, and what percentage of your cap is used.
The formula explained
Overage data is the amount you exceeded your cap by, floored at zero so it never goes negative: \( \text{overage\_GB} = \max(0,\ \text{used\_GB} - \text{cap\_GB}) \). The extra charge is simply that overage multiplied by the per-GB price: \( \text{cost} = \text{overage\_GB} \times \text{price\_per\_GB} \). If you're still under your cap, both values are zero.
$$\text{Overage Cost} = \max\!\left(0,\ \text{Used (GB)} - \text{Cap (GB)}\right) \times \text{Price (\$/GB)}$$
Worked example
Suppose you've used 350 GB on a 300 GB plan, and your provider charges $10 per extra GB. Overage = \( \max(0,\ 350 - 300) = 50 \) GB. Cost = \( 50 \times \$10 = \) $500. You have 0 GB remaining and have used about 116.67% of your cap.
$$\text{Overage} = \max(0,\ 350 - 300) = 50\ \text{GB}$$$$\text{Cost} = 50 \times \$10 = \$500$$
FAQ
What if I'm under my cap? The overage and cost both show $0 and you'll see how much data remains.
Where do I find the price per GB? Check your plan terms or recent bill — overage rates are usually listed in the fine print, often $5–$15 per GB.
Are units the same for cap and usage? Yes — enter both in GB. If your provider uses MB, divide by 1024 first (\( 1\ \text{GB} = 1024\ \text{MB} \)).
