Example result based on the prefilled values.
Daily Usage
44.80kWh
Monthly Cost
NZ$84.03
Annual
NZ$1,008.86
Continue your plan
Useful next calculations
When to use this calculator
- Before switching supplier, upgrading equipment, or comparing energy-saving changes.
- When you want to test different usage assumptions or price scenarios quickly.
- When you need a simple estimate before requesting installer or supplier quotes.
- When you are evaluating solar panels, a heat pump, or insulation and want to check the payback period before spending.
- When your tariff is about to change and you want to quickly model the impact on your annual energy bill.
A realistic New Zealand planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
Gas Usage Per Day (m³)
15
Unit Rate (p/kWh)
5%
Standing Charge (p/day)
15
After entering these figures, review daily usage, monthly cost and annual together rather than in isolation — each metric tells a different part of the story. Then rerun the tool with one input adjusted to see which variable has the biggest effect on all three outputs before you settle on a plan.
How to read your results
Daily Usage
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Monthly Cost
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Annual
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Method & assumptionsAuthoritative sources
This calculator works out your estimated gas bill by taking your average daily usage in kWh, multiplying it by the unit rate on your tariff, and adding the daily standing charge over your chosen period. Usage figures can be found on a recent gas bill or taken from a smart meter in-home display. Because gas consumption varies significantly with the seasons, the calculator is most accurate when you enter usage figures that reflect the period you are planning for — use a winter month's reading to project winter costs rather than an annual average. Gas VAT in Great Britain is charged at the reduced rate of 5%, and suppliers quote their rates inclusive of this, so no additional adjustment is needed. Actual bills may differ due to meter reading cycles, direct debit smoothing, and any standing charge changes mid-contract.
Common mistakes
- !Using an assumption that is not supported by a current local quote, bill, statement or official source.
- !Treating a generic estimate as a lender, provider, payroll or tax authority decision.
- !Mixing monthly and annual inputs without converting them consistently.
- !Forgetting location-specific taxes, fees, eligibility rules or payroll deductions where they apply.
- !Testing only one scenario instead of checking how a cautious assumption changes the result.
What to do next
- Run a second scenario with a cautious assumption so you can see the downside clearly.
- Compare the result with the related calculators below before making a decision.
- Check current local rules, eligibility and provider terms before applying or committing money.
- Keep a record of the assumptions so you can update the estimate when a quote, bill or pay figure changes.
- Use the result to prepare better questions for a lender, provider, adviser or employer rather than treating it as a final answer.
Frequently asked
Use arrow keys to navigate items, Enter or Space to expand/collapse.