Set a monthly utility budget
Use actual bills for a budget history and usage estimates for planning. Record currency and unit consistently so that comparisons remain meaningful. Seasonal heating or cooling makes one month a poor annual baseline.
Variance and monthly change
A monthly variance is actual bill minus budget. For example, a USD 92 bill against a USD 85 budget is USD 7 over budget. If last month was USD 80, the increase is USD 12, or 15%. A prior bill of zero has no meaningful percentage change.
Budget for the seasons
Review at least a full seasonal cycle when records are available. Set aside a larger allowance for months you expect to cost more, and distinguish a billing adjustment from an ongoing usage change.
Protect your history
The tracker stores one record per utility per calendar month in your browser. Saving the same month and utility replaces that record. Export a JSON copy periodically; clearing browser storage can remove the local history.
Budget timing matters
For bills arriving every two months, a monthly allowance is a reserve rather than a prediction of a monthly statement. Keep payment timing separate from service-period use. Do not represent a missing bill as zero. Review rate notices and fixed fees when revising the next allowance.
Worked example: Check a shared monthly budget by utility
Related reading: Comparing utility bills across years without misleading yourself