Sizu Riatto
Watt Happens Next · Chapter 11

The Bill Score

You called it; the bill keeps score. Within 5% of the corrected bill is Gold, and an audit that caught a wrong line is worth a level of its own.

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Opens on the book's call and its bill. Enter your own call, the bill, and your Call It results through the season.

The Bill Score: your call against the bill

The season scoreboard: your ten Call Its (blank = not played yet)

Enter your call and the bill, then press Calculate.

The formula

  • Gap = |the bill − your call| ÷ the bill, scored against the corrected bill once every line is right
  • Gold within 5%; Silver within 10%; Bronze within 20% with the audit sheet complete
  • Audit level: every line on the bill reproduced from your own reads and tariff
  • Each Call It: within 5% scores 3 points, within 10% 2, within 20% 1; ten chapters, 30 points
The book's worked example, Chapter 11. The book called 308.95 ± 22.58. The bill came as 343.11, 9.96% away: Silver. The audit found the estimated gas read; corrected, the bill is 320.55, inside the band and 3.6% from the call: Gold. The audit was worth a level.
Check it. Score yourself against the bill as sent and the corrected bill: if they give different levels, the audit earned its keep.

Honest limits. A level is a record of how well your model matched your month, not a grade of your household. A miss is information: find out why, because that is the chapter. The book's house, its meters and its bill were worked out on paper from published figures, not measured by us: read your own meters and log your own night. Tariffs are illustrative, as seen in November 2026 (shaped like the GB price cap of October to December 2026, with US prices beside), shown without a currency sign; put in your own. No saving is promised. Everything stays in your browser: no sign-up, nothing stored.

These calculators go with Watt Happens Next (Make It Add Up, Book 3), where every number on this page is worked by hand.