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Smart Meter Savings Calculator

Last updated: April 2026

Current electricity use

Target tariff

What can you shift off-peak?

Shiftable usage: 15%

Total saving

£98/year

New annual bill

£902

Saving

9.8%

Saving breakdown

Behaviour change (3.5%)
£35.00
Tariff optimisation
£62.77
EV off-peak charging
£0.00
Storage heating
£0.00
Total saving
£97.77

Hourly cost comparison

Current rate
24.5p/kWh all day
Octopus Go off-peak
9p/kWh (4hrs/day)
Octopus Go peak
24.5p/kWh

Best times to run appliances on Octopus Go

Washing machine

00:30-04:30

Dishwasher

00:30-04:30

EV charging

00:30-04:30

Smart meter note

Smart meters are free to install and required to access time-of-use tariffs. Your supplier is obliged to offer you one on request.

What is a time-of-use tariff?

A time-of-use tariff charges different electricity rates depending on when you use it. Off-peak periods are usually cheaper, so moving flexible use such as laundry, dishwashers, and EV charging overnight can reduce bills.

What is Octopus Go?

Octopus Go is a time-of-use electricity tariff with a low overnight rate, currently around 9p/kWh, between 00:30 and 04:30. It is especially useful for EV owners who can charge overnight.

Do smart meters save money?

Smart meters do not directly reduce bills, but they make usage visible and enable time-of-use tariffs. Studies show this can reduce consumption by around 3-4%, with larger savings for flexible usage or EV charging.

About this calculator

The Smart Meter Savings Calculator helps households estimate savings from better usage visibility, time-of-use tariffs, EV charging shifts, and storage-heating changes. It is useful when comparing a standard tariff with a smart tariff or deciding whether behaviour changes could reduce bills. Use this expanded guide when you need more than a quick result. It explains the assumptions behind the Smart Meter Savings Calculator, the records to gather, and the decisions the estimate can support. It is especially useful for households comparing smart tariffs, EV charging schedules, storage heating, and energy-use behaviour changes. The strongest use of the page is scenario comparison: change one input at a time, compare the output, and keep a note of which assumption changed.

Smart Meter Savings Calculator calculation method

The calculator estimates a behaviour saving percentage on the current bill and separately models shiftable electricity use moved from peak to off-peak rates. EV miles, miles per kWh, storage heating use, and tariff rates can all change the result. The calculator result depends on the quality of the inputs and on the rule set or formula selected in the calculator above. For practical use, treat the output as a structured estimate: start with the core inputs, review the main outputs, then test the decision points that matter most to your situation. Key decisions include whether a smart tariff may save money, how much use to shift off-peak, whether behaviour changes are enough.

  • behaviour saving = annual bill x behaviour saving percentage
  • EV charging kWh = EV miles / miles per kWh
  • tariff saving = shifted kWh x (peak rate - off-peak rate)
  • better estimate = accurate inputs + correct rule set + realistic assumptions
  • scenario difference = revised result - original result

How to use the Smart Meter Savings Calculator

  1. Enter your current annual energy bill or electricity use.
  2. Add peak and off-peak rates if comparing a smart tariff.
  3. Enter shiftable usage such as EV charging or storage heating.
  4. Check the behaviour saving estimate separately from tariff saving.
  5. Run a conservative scenario with less shiftable use.
  6. Compare the result with real tariff standing charges and exit fees.
  7. Use smart meter data to update the estimate after a few months.
  8. Gather the main inputs first: annual bill, peak rate, off-peak rate.
  9. Check supporting records such as energy bills and smart meter data before relying on a final number.
  10. Enter one realistic scenario first, using conservative assumptions where the future is uncertain.
  11. Review the main outputs: behaviour saving, tariff saving, total annual saving.
  12. Run at least one alternative scenario so you can see which input changes the answer most.
  13. Compare the result with Ofgem smart meter advice and supplier tariff documents or the relevant contract, bill, statement, or professional document.
  14. Keep the calculation date and assumptions with your notes so you can revisit the estimate when rates, rules, or circumstances change.

Worked example

EV charging moved off-peak

Input: 2,400 kWh of annual EV charging moves from 28p/kWh to 9p/kWh.

Calculation: 2,400 x GBP 0.19 = GBP 456 annual saving before any standing charge or tariff differences.

Result: The calculator shows why EV charging can make smart tariffs more valuable for some households.

No shiftable load scenario

Input: A household has no EV, no battery, and little appliance use overnight.

Calculation: Only the behaviour saving assumption applies.

Result: The estimate is modest and tariff switching should be checked carefully.

High peak rate scenario

Input: Off-peak charging is cheap but daytime electricity is more expensive.

Calculation: Savings from shifted usage are compared with extra cost on non-shifted usage.

Result: The household needs a full-tariff comparison, not just the off-peak rate.

A smart meter does not save money by itself

Savings usually come from behaviour changes, accurate billing, and access to tariffs that reward shifting usage. If a household cannot shift meaningful electricity use, the financial saving may be modest.

The in-home display and half-hourly data can still be useful for spotting waste, but the calculator should be tested with realistic behaviour assumptions.

What to check before relying on the result

A useful Smart Meter Savings Calculator result starts with the same evidence you would use if you were checking the answer manually. The calculator can organise the arithmetic, but it cannot know whether a payslip is final, a bill is estimated, a quote excludes fees, or a personal circumstance has changed since the last statement.

Before making a decision, compare the calculator result with the source document that controls the real outcome. For this topic, that usually means checking Ofgem smart meter advice and supplier tariff documents. If there is a difference between the calculator and an official statement, contract, assessment, or professional advice, treat the official document as the stronger source.

energy bills
Use this as supporting evidence for the calculation. If it is out of date, estimated, or based on a different period, the calculator output may look precise while still being wrong for the decision.
smart meter data
Use this as supporting evidence for the calculation. If it is out of date, estimated, or based on a different period, the calculator output may look precise while still being wrong for the decision.
tariff quote
Use this as supporting evidence for the calculation. If it is out of date, estimated, or based on a different period, the calculator output may look precise while still being wrong for the decision.
EV charging log
Use this as supporting evidence for the calculation. If it is out of date, estimated, or based on a different period, the calculator output may look precise while still being wrong for the decision.
supplier terms
Use this as supporting evidence for the calculation. If it is out of date, estimated, or based on a different period, the calculator output may look precise while still being wrong for the decision.

Inputs that usually change the answer

The most important input is not always the largest number on the form. Sometimes a date, threshold, percentage, eligibility flag, or timing assumption changes the result more than the headline amount. This is why scenario testing is more useful than a single calculation.

InputWhy it mattersWhat to double-check
annual billIt feeds directly into the estimate or changes which rule is applied.Check the period, units, eligibility, and whether the figure is final or estimated.
peak rateIt feeds directly into the estimate or changes which rule is applied.Check the period, units, eligibility, and whether the figure is final or estimated.
off-peak rateIt feeds directly into the estimate or changes which rule is applied.Check the period, units, eligibility, and whether the figure is final or estimated.
shiftable kWhIt feeds directly into the estimate or changes which rule is applied.Check the period, units, eligibility, and whether the figure is final or estimated.
EV milesIt feeds directly into the estimate or changes which rule is applied.Check the period, units, eligibility, and whether the figure is final or estimated.

How to interpret the output

The output should be read as a decision aid, not just a number. For Smart Meter Savings Calculator, the useful question is often what the result means for timing, affordability, eligibility, comparison, or next steps.

behaviour saving
Use this output alongside the other results rather than in isolation. A monthly amount, percentage, date, or payback figure can look acceptable until fees, timing, evidence, or eligibility conditions are added.
tariff saving
Use this output alongside the other results rather than in isolation. A monthly amount, percentage, date, or payback figure can look acceptable until fees, timing, evidence, or eligibility conditions are added.
total annual saving
Use this output alongside the other results rather than in isolation. A monthly amount, percentage, date, or payback figure can look acceptable until fees, timing, evidence, or eligibility conditions are added.
payback note
Use this output alongside the other results rather than in isolation. A monthly amount, percentage, date, or payback figure can look acceptable until fees, timing, evidence, or eligibility conditions are added.

Scenarios worth comparing

A single estimate is a snapshot. A better approach is to save a base case, then adjust one assumption at a time. This shows whether the result is stable or whether a small change in timing, rate, usage, income, or cost creates a very different answer.

ScenarioChange one assumptionWhat the comparison shows
Base caseUse the best current evidence.Shows the result you would expect if nothing important changes.
Conservative caseUse lower income, higher cost, slower growth, or less favourable timing.Shows whether the decision still works with less optimistic assumptions.
Improved caseUse the realistic upside, such as lower cost, better rate, higher usage, or stronger evidence.Shows the potential benefit without treating it as guaranteed.

Common mistakes and edge cases

Most errors come from using the right formula with the wrong assumption. Dates can be counted differently, rates can change, official thresholds can move, and real bills or contracts often include conditions that a simple calculator cannot infer automatically.

Peak prices can rise.
Check this point before using the estimate for a payment, claim, purchase, application, employment decision, or health-related decision.
Standing charges may differ.
Check this point before using the estimate for a payment, claim, purchase, application, employment decision, or health-related decision.
Savings need real behaviour change.
Check this point before using the estimate for a payment, claim, purchase, application, employment decision, or health-related decision.
Smart meter communication can fail temporarily.
Check this point before using the estimate for a payment, claim, purchase, application, employment decision, or health-related decision.

Next steps after calculating

Once you have a result, write down the key assumptions and compare them with Ofgem smart meter advice and supplier tariff documents. If the number affects a deadline, tax return, benefit claim, employment issue, medical question, finance agreement, or major purchase, use the calculator as preparation for a more formal check.

For lower-stakes use, the next step may simply be comparing two or three scenarios. For higher-stakes use, the next step should be checking the official guidance, speaking to the relevant organisation, or getting qualified advice before acting.

Common mistakes and edge cases

  • Some smart tariffs have higher peak rates or standing charges.
  • A smart meter may temporarily lose smart functionality after supplier changes.
  • EV and storage-heating savings depend on how much use can genuinely shift.
  • Gas savings from a smart meter are usually behavioural, not tariff-based.
  • Peak prices can rise.
  • Standing charges may differ.
  • Savings need real behaviour change.
  • Smart meter communication can fail temporarily.

Limitations and advice boundary

This calculator is general information only and is not energy or financial advice. Check actual supplier tariffs and smart meter terms. This is general information only and is not energy or financial advice. The calculator is designed to support understanding and planning, but it cannot verify documents, predict future rule changes, or account for every exception. Use it as an estimate and check the official source before acting where the result matters.

  • Use the result as an estimate and keep the source documents used for the inputs.
  • Check current official guidance, contracts, bills, statements, or professional advice where the result affects a real decision.
  • Run a conservative scenario as well as the main scenario where costs, dates, rates, eligibility, or behaviour may change.
  • Check Ofgem smart meter advice and supplier tariff documents for current rules, rates, definitions, and eligibility where relevant.
  • Do not rely on a single scenario where income, costs, dates, rates, usage, or health circumstances may change.
  • Keep records of the inputs used so that the estimate can be reviewed later.

Frequently asked questions

Do I pay separately for a smart meter?

Under current arrangements, smart metering costs are recovered through bills rather than a separate installation charge for most households.

Will it automatically reduce my bill?

No. Savings depend on usage changes, tariff choice, and accurate billing.

Can renters get a smart meter?

If you pay the energy bill you can often request one, but check tenancy terms and tell the landlord where relevant.

Can smart meters work with prepayment?

Yes, smart meters can operate in prepayment or credit mode.

Do smart meters send automatic readings?

That is one of the main benefits when the meter is operating in smart mode.

Should I share half-hourly data?

Data choices depend on supplier rules and your privacy preferences; check the supplier settings.

Related calculators

  • Electricity Cost Calculator
  • Energy Direct Debit Calculator
  • Energy Bill Calculator
  • EV Charging Cost Calculator

What does this mean?

This calculator is designed to help you understand the likely number before you make a decision or start an application.

Your result should be checked against official UK guidance, especially if your circumstances include dependants, exemptions, prior leave, or a complex immigration history.

Treat the figure as a planning tool rather than legal advice. Where the answer affects an application deadline or major payment, speak to an authorised adviser.

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