Handy Little Tools / Electricity usage investigator
Where did the extra electricity go?
Compare meter readings from two periods. Find when usage changed, check gaps, and keep a report of what the data actually shows.
Your file stays in this browser tab. No upload, account, automatic saving or appliance guessing.
1. Open interval readings
Use a supported Green Button XML export or our explicit interval-kWh CSV format. This pilot supports one import meter, up to 110,000 readings and 32 MiB decoded text.
Supported formats and important limits
CSV header: start,duration_seconds,kwh,quality. Example row: 2026-01-01T00:00:00Z,3600,0.5,unknown. Times need Z or an explicit UTC offset; values must be nonnegative interval energy, not cumulative meter readings. Quality is measured, estimated or unknown. No quoted fields.
XML must link one meter to interval Wh readings and its ReadingType. Multiple meters, export energy, unsupported units and ambiguous links are rejected. Source quality codes are preserved without interpretation. Compatibility has been tested with two licensed repository specimens, not every utility.
Comparisons need equal elapsed lengths. Partial intervals and records spanning display-hour boundaries are rejected. Unsupported local clock rules fall back to UTC. This tool cannot explain price changes, fees, faulty meters or which appliance used the energy.
Choose a file or try the synthetic example.
3. Follow the evidence
Observed usage, with the gaps left visible
A difference does not identify an appliance or prove a billing error. Missing readings, estimates and mismatched bill boundaries remain questions to resolve.
Which hours changed?
Totals across each selected period, grouped by hour. Earlier Later. Click an hour to inspect its readings. Incomplete coverage can make a difference misleading.
Later-period days
Observed daily energy. Click a day to inspect its records. Coverage is elapsed recorded time; a local DST day may have 23 or 25 hours. Entirely missing days appear in the gap list below.
Missing intervals
Trace the finding to readings
| Source | Period | UTC start | Display time / UTC offset | Seconds | kWh | Quality |
|---|
How to compare electricity usage between bills
Download interval energy readings from your electricity provider, if available. This experiment accepts the explicit CSV format above and a narrow one-meter Green Button XML form. Enter the earlier and later boundaries and the later bill's kWh, then check coverage before interpreting the hour-by-hour differences.
Why might the bill and meter export disagree?
Different date boundaries, missing intervals, estimated readings or adjustments can leave a difference. Start by checking those records. The tool reports the unresolved amount; it does not establish which explanation is correct.
Can this tell me which appliance caused an increase?
No. Aggregate interval usage identifies times worth investigating, not individual devices. A higher currency total can also reflect rates or fees even when energy use is unchanged.
What if my utility export is unsupported?
Keep the original file. You can prepare the documented CSV if you can verify its timestamps, duration, units and quality; do not guess a unit multiplier or replace cumulative register values with interval energy. See the Department of Energy's Green Button overview for background on utility exports.