Mobile data usage calculator

Travelers roaming on a prepaid SIM, parents sharing a family pool, field workers on a capped work line, and support desks that quote remaining data all need a deterministic answer that does not log into a carrier account or scrape a billing portal. This calculator accepts a monthly limit in megabytes and one or more usage entries also in megabytes, sums the consumed amount, subtracts it from the limit, and returns data left plus percent used.

How remaining mobile data and percent used are computed

Rounding is fixed to twelve decimal places for megabyte fields and four decimal places for percents so browser and API goldens stay byte-stable across runtimes without floating noise on simple sums.

Input contract, response shape, and error behaviour

Each entry may be a bare number treated as an amount, or an object with amount required and label optional. Example: a ten thousand two hundred forty megabyte plan with streaming at two thousand four hundred, maps at one hundred eighty, social at eight hundred fifty, and email at forty yields three thousand four hundred seventy megabytes used and six thousand seven hundred seventy megabytes left, about thirty three point nine percent used. Lists longer than five hundred entries are rejected to keep pure-parse work bounded. POST a JSON body with two required fields: limit_mb, a finite number of megabytes greater than zero, and usage, a non-empty array of usage entries. Amount also accepts common aliases such as mb, value, or used; the list field itself accepts aliases entries, usage_mb, amounts, and items. The limit field accepts aliases monthly_limit, limit, allowance, quota, and plan_mb so scripts can reuse vocabulary from carrier dashboards. On success the body echoes the limit, the entry count, each line with a stable label, rounded amount, and running remaining after that line, plus used_mb, remaining_mb, percent_used, percent_remaining, over_limit, overage_mb, a short formula string, a human message, and ordered steps for worksheets. If the same style of list sums past the limit, over_limit is true and overage_mb shows how far past the cap you went, still a successful response, because exceeding the plan is a question the calculator answers. Missing limit, empty usage, non-finite numbers, or any negative usage value fail with invalid_input naming the field and are not billed. Successful API calls use the published base of $0.002 per item.

Where a mobile data usage calculator earns its keep

Parents sharing a family plan enter each child's app totals and stop tethering when percent used crosses a household threshold. Keep requests small, pin rounded megabyte totals in tests, and you get reproducible remaining data for phone checklists, LMS plugins, and edge workers without standing up a carrier integration of your own. Prepaid travelers keep a running list of hotspot sessions and video calls so they can see remaining megabytes before a boarding-gate download eats the rest of a roaming pack. Small offices with capped work SIMs post daily usage entries into a bot that flags over_limit before a field tablet starts an unplanned software update. Classroom units on digital literacy assign remaining-data exercises; an API with running remaining after each line lets graders see which session first crossed the monthly cap. Automation scripts that schedule firmware updates or cloud backups can halt a job when remaining_mb would go negative.