How we calculate your savings

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Hermes

Last updated on Jul 6, 2026

There are three main savings calculations used in the Bill Hero service:

  • Bill Savings

  • Annualised Savings

  • Lifetime Savings

Bill Savings

We use the detailed data from your bill to calculate what you would have paid for that same usage with the same tariff type over the equivalent time period under all the relevant publicly available plans on the market.

We include tariff type, solar feed-in, guaranteed & conditional discounts, and incentives.

The difference between what you were actually charged in your bill vs the best available price you would have been charged under an alternative plan is the Bill Savings.

Bill Savings calculation uses the historical consumption and bill period data as documented in your bill to calculate what you would have been charged under each of the currently available plans. It's possible that the current pricing may not have been available during the billing period under consideration. That's why we refer to this as 'equivalent' time period.

Annualised Savings

In your results for each bill analysed, Bill Hero expresses your savings as an annualised amount by applying the Bill Savings pro-rata over a full year. Annualising the savings result aligns the savings with the annual subscription period, which makes it possible for us to provide the Savings Guarantee.

At its most simplistic level, an annualised savings example would be if $10 savings are found in a single monthly bill, then this could be expressed as $120 of annualised savings. We actually calculate Annualised Savings on the number of days in the billing cycle rather than months, but you get the idea.

Bill Hero applies a seasonal indexing factor to the annualised savings calculations for electricity and gas to adjust for seasonal variations in consumption.

Legend Zone Description
Climate Zone 1 Hot humid summer, warm winter
Climate Zone 2 Warm humid summer, mild winter
Climate Zone 3 Hot dry summer, warm winter
Climate Zone 4 Hot dry summer, cool winter
Climate Zone 5 Warm temperate
Climate Zone 6 Mild temperate
Climate Zone 7 Cool temperate
Climate Zone 8 Alpine

Electricity Annualised Savings

For electricity annualised savings, the calculation takes seasonal variation in electricity consumption into account, based on an index of average seasonal electricity consumption by state and climate zone.

The indexed values are based on seasonal electricity usage data published by the AER for each state, broken down by Climate Zone and geographic region.

QLD

Climate Zone Autumn Summer Winter Spring
CZ 1 1.01 1.17 0.86 0.96
CZ 2 1.00 1.11 0.96 0.92
CZ 3 0.97 1.24 0.85 0.94
CZ 5 0.96 1.01 1.10 0.93

NSW

Climate Zone Autumn Summer Winter Spring
CZ 2 0.99 1.00 1.06 0.96
CZ 4 0.93 0.88 1.18 1.01
CZ 5 0.95 0.99 1.15 0.91
CZ 6 0.93 1.04 1.11 0.92
CZ 7 & 8 0.93 0.67 1.40 1.00

ACT

Autumn Summer Winter Spring
0.91 0.65 1.42 1.02

TAS

Autumn Summer Winter Spring
0.91 0.65 1.41 1.03

VIC

Climate Zone Autumn Summer Winter Spring
CZ 4 0.87 0.92 1.29 0.93
CZ 6 0.96 0.98 1.15 0.91
CZ 7 & 8 0.90 0.71 1.39 0.99

SA

Region Autumn Summer Winter Spring
Adelaide & Environs 0.96 0.98 1.13 0.94
Mt Lofty Ranges 0.96 0.94 1.15 0.94
Yorke Peninsula & Kangaroo Island 0.96 0.97 1.13 0.94
Marylands & Riverland 0.95 0.97 1.13 0.94
South East 0.96 0.94 1.15 0.94
Mid north 0.96 0.93 1.10 1.00
Central north 0.95 0.96 1.14 0.95
Pt Augusta & Pastoral 0.93 0.96 1.15 0.96
Eastern 0.92 0.95 1.16 0.96
West coast 0.95 0.98 1.13 0.94

Bill Hero will apply the appropriate index value when calculating your annualised savings.

Electricity Annualised Savings formula

Electricity Annualised Savings = Electricity Bill Season Savings x 365.25 / Electricity Bill Season Days / Electricity Seasonal Index value

Where the electricity billing period spans two or more seasons, Bill Hero will split the total bill duration days into season-days to find the proportion of the billing period in each season. Then, using the same proportion, Bill Hero will split the total Electricity Bill Savings into Electricity Bill Season Savings, apply the relevant Seasonal Index value for each Electricity Bill Season Savings value, and aggregate the result.

Gas Annualised Savings

For gas savings, the annualisation calculation takes seasonal variation in gas consumption into account, based on an index of average seasonal gas consumption by state.

The indexed values are based on seasonal gas usage data published by the AER

State Autumn Summer Winter Spring
Queensland 0.94 0.69 1.36 1.01
New South Wales 0.88 0.55 1.57 1.00
ACT 0.85 0.27 1.86 1.02
Victoria 0.79 0.36 1.83 1.02
Tasmania 0.79 0.29 1.88 1.04
South Australia 0.79 0.50 1.62 1.08
Official Aust Season periods March, April and May December, January and February June, July and August September, October and November

Gas Annualised Savings formula

Gas Annualised Savings = Gas Bill Season Savings x 365.25 / Gas Bill Season Days / Gas Seasonal Index value

Where the gas bill period spans across two or more seasons, Bill Hero will split the total bill duration days into season-days to find the proportion of the billing period in each season, then use the same proportion to split the total Gas Bill Savings into Gas Bill Season Savings, and apply the relevant Seasonal Index value for each Gas Bill Season Savings value, then aggregate the result.

Lifetime Savings

Bill Hero also keeps a running tally of your cumulative lifetime savings over the lifetime of your subscription.

For each bill processed by Bill Hero, where Annualised Savings are greater than your Savings Guarantee (on your first bill) or greater than your Bothered Threshold (on your second and subsequent bills), we add the Annualised Savings amount to your Lifetime saving tally - this is because we assume you will complete the switch to access those savings.

Where annualised savings are lower than your Bothered Threshold, we will add the individual Bill Savings amount to your Lifetime Savings tally.

You can see your Lifetime Savings tally in a panel in the email results you receive for each bill processed by Bill Hero.