Enrichment · Life Skills · Digital

Every kilobyte
is a wait.

Copy the sizes from your browser’s Network tab. The calculator totals the page against a budget, estimates load time on a slow phone and points at what to trim.

Check my pageWhat you get

The webpage performance budget calculator

The worked example is a robotics club home page with large photos. Nothing you type leaves this browser.

Loading the calculator. If nothing appears, turn on JavaScript.

What you get

Enrichment · Life SkillsFree

What you finish with
Total weight and file count against your budget, each type’s share, estimated load time on three connections and the first thing to trim. It prints as a summary for the team that maintains the site.
Who it is for
Students building a site for a class or club, volunteers who keep a small organization’s website, and beginning web developers.
Format
Browser calculator for a phone, tablet or computer, by touch or keyboard. Prints a summary; downloads a spreadsheet (.csv); export and import a file.
Access
Free. No account, no sign-in and nothing to install. Everything you type stays in this browser; nothing is sent to Caveat.
Where it lives
The Life Skills space in Caveat Enrichment.
Support
Questions, a correction or a request: team@caveatacademic.com.

How to use it

  1. Open the Network tab and reload.
  2. Group the files by type.
  3. Type kilobytes and file counts.
  4. Set a budget.
  5. Trim the heaviest type first.

Check my page

How load time is estimated

Round trips plus bytes over bandwidth.

The worked example: a robotics club home pageWeight1,820 KB34 filesRound trips8 × 150 mssetup + batches of 6Transfer9.1 sat 1.6 MbpsSlow mobile10.3 sestimated loadThe worked example: a robotics club home pageWeight1,820 KB34 filesRound trips8 × 150 mssetup + batches of 6Transfer9.1 sat 1.6 MbpsSlow mobile10.3 sestimated load
Round trips set a floor that bandwidth cannot fix; bytes divided by bandwidth set the rest.

Two costs

Every connection and every batch of files costs round trips, the time for a message to reach the server and come back. On a slow phone network a round trip can take 150 milliseconds before a single byte arrives. Then the bytes themselves take size divided by bandwidth. Fewer files cut the first cost; smaller files cut the second.

Why a budget

A budget is a limit the team agrees on before adding a new photo or script, so the page stays fast as it grows. Images are usually the heaviest part and the easiest to shrink: resize them to the size they show at and save them in a modern format.

Sources

  1. web.dev (Google). Performance budgets 101 and Learn Performance (web.dev).
  2. Chrome for Developers. Lighthouse: network throttling and performance scoring (developer.chrome.com).
  3. HTTP Archive. Web Almanac: page weight chapter (almanac.httparchive.org).
  4. MDN Web Docs. Web performance: fundamentals and measuring (developer.mozilla.org).

The load-time model is a simplification for planning; measure the real page with your browser’s tools. Your entries stay in this browser. Support: team@caveatacademic.com.