Quick Answer: How Is a Website Hosting Bill Calculated?
Most metered hosting plans charge a flat monthly base fee that includes an allowance of bandwidth (data transferred to visitors) and storage, then a per-GB rate for anything beyond it: Total = Base Fee + Bandwidth Overage + Storage Overage, where each overage is max(0, Used - Included) × Rate.
Worked example (the calculator's Shared preset): an $8/month plan including 100 GB bandwidth and 20 GB storage, with overage at $0.10/GB and $0.15/GB. A busy month uses 250 GB and 35 GB. Bandwidth overage = (250 − 100) × $0.10 = $15.00. Storage overage = (35 − 20) × $0.15 = $2.25. Total = $25.25, more than three times the advertised base price.
The presets are illustrative numbers, not any provider's price list, and the result is an estimate rather than a quote. Replace every field with the figures on your own plan's pricing page or invoice.