Calculators

Household electricity cost by region and appliance

What a New Zealand household pays for power.

The arithmetic is kilowatts times hours times rate, which any model does unaided. What it cannot know is the New Zealand price data: Wellington pays 34.61c a unit and Balclutha 48.93c, a 41% spread across one small country, from MBIE's Quarterly Survey of Domestic Electricity Prices.

The fixed charge is why a bill is never just usage. Every connection carries a daily charge whatever you use, so a low user pays a larger share of their bill simply for being connected. It is returned separately from the usage cost, because advice that only addresses usage is aiming at part of the target. The low fixed charge regulations are being phased out in steps rather than scrapped: capped at $1.80 a day from 1 April 2026 and revoked on 1 April 2027.

biggest_users is the field to lead with. A heat pump and a hot water cylinder dominate almost every bill, and standby power almost never does, which is the opposite of where most saving advice points.

The household multiplier is a model, not a measurement: it scales a typical appliance profile from 0.60 for one person to 1.30 for five or more. Anyone who knows their own usage should pass appliance_hours instead.

post/v1/electricity-cost

Request

  • Base URL: https://api.calculate.co.nz
  • URL: https://api.calculate.co.nz/v1/electricity-cost
  • Auth: API key in header X-API-Key

Request body

regionstring

One of the MBIE survey towns, or "nz average". Case insensitive. The spread is wide: Wellington 34.61c against Balclutha 48.93c.

household_sizeinteger

1 to 5, where 5 means five or more. Scales the appliance profile.

daily_fixed_chargenumber

The daily connection charge in DOLLARS, from your bill. Typically $0.30 to $2.50. Charged whatever you use.

custom_rate_centsnumber

Your own rate in cents per kWh including GST. Overrides the region.

appliance_hoursobject nullable

Override any appliance's daily hours, keyed by heat_pump, hot_water, oven, clothes_dryer, ev_charger, fridge_freezer, dishwasher, washing_machine, stovetop, induction_cooktop, tv, computer, lights, electric_heater.

Example request

{
  "custom_rate_cents": 0,
  "daily_fixed_charge": 1.5,
  "household_size": 3,
  "region": "auckland"
}

Response

Daily, monthly and annual cost, with the appliances ranked.

disclaimerstring required

Scope and limits of this calculation.

Example response

{
  "disclaimer": "Indicative. Regional rates are MBIE QSDEP February 2026 for a modelled household on a standard tariff; actual cost depends on your retailer, plan, tariff structure and usage. Compare plans at powerswitch.org.nz.",
  "result": {
    "annual_at_nz_average": 5038.76,
    "annual_kwh": 11428.15,
    "annual_total": 4947.34,
    "appliances": [
      {
        "annual_cost": 1264.73,
        "daily_cost": 3.47,
        "hours_per_day": 6,
        "kwh_per_day": 9,
        "name": "Heat pump",
        "watts": 1500
      },
      {
        "annual_cost": 1264.73,
        "daily_cost": 3.47,
        "hours_per_day": 3,
        "kwh_per_day": 9,
        "name": "Hot water cylinder",
        "watts": 3000
      },
      {
        "annual_cost": 281.05,
        "daily_cost": 0.77,
        "hours_per_day": 1,
        "kwh_per_day": 2,
        "name": "Oven",
        "watts": 2000
      },
      {
        "annual_cost": 337.26,
        "daily_cost": 0.92,
        "hours_per_day": 1,
        "kwh_per_day": 2.4,
        "name": "Clothes dryer",
        "watts": 2400
      },
      {
        "annual_cost": 0,
        "daily_cost": 0,
        "hours_per_day": 0,
        "kwh_per_day": 0,
        "name": "EV charger (7kW)",
        "watts": 7000
      },
      {
        "annual_cost": 505.89,
        "daily_cost": 1.39,
        "hours_per_day": 24,
        "kwh_per_day": 3.6,
        "name": "Fridge/freezer",
        "watts": 150
      },
      {
        "annual_cost": 252.95,
        "daily_cost": 0.69,
        "hours_per_day": 1,
        "kwh_per_day": 1.8,
        "name": "Dishwasher",
        "watts": 1800
      },
      {
        "annual_cost": 70.26,
        "daily_cost": 0.19,
        "hours_per_day": 1,
        "kwh_per_day": 0.5,
        "name": "Washing machine",
        "watts": 500
      },
      {
        "annual_cost": 105.39,
        "daily_cost": 0.29,
        "hours_per_day": 0.5,
        "kwh_per_day": 0.75,
        "name": "Stovetop/hob",
        "watts": 1500
      },
      {
        "annual_cost": 140.53,
        "daily_cost": 0.39,
        "hours_per_day": 0.5,
        "kwh_per_day": 1,
        "name": "Induction cooktop",
        "watts": 2000
      },
      {
        "annual_cost": 56.21,
        "daily_cost": 0.15,
        "hours_per_day": 4,
        "kwh_per_day": 0.4,
        "name": "TV",
        "watts": 100
      },
      {
        "annual_cost": 50.59,
        "daily_cost": 0.14,
        "hours_per_day": 6,
        "kwh_per_day": 0.36,
        "name": "Computer/laptop",
        "watts": 60
      },
      {
        "annual_cost": 70.26,
        "daily_cost": 0.19,
        "hours_per_day": 5,
        "kwh_per_day": 0.5,
        "name": "LED lights (10 bulbs)",
        "watts": 100
      },
      {
        "annual_cost": 0,
        "daily_cost": 0,
        "hours_per_day": 0,
        "kwh_per_day": 0,
        "name": "Electric heater (fan)",
        "watts": 2000
      }
    ],
    "biggest_users": [
      "Heat pump",
      "Hot water cylinder",
      "Fridge/freezer"
    ],
    "cheapest_region": {
      "name": "wellington",
      "rate": 34.61
    },
    "daily_fixed_charge": 1.5,
    "daily_kwh": 31.31,
    "daily_kwh_before_multiplier": 31.31,
    "daily_total": 13.55,
    "daily_usage_cost": 12.05,
    "household_multiplier": 1,
    "household_size": 3,
    "monthly_total": 412.05,
    "most_expensive_region": {
      "name": "balclutha",
      "rate": 48.93
    },
    "note": "The daily fixed charge is separate from usage, so a low user pays a larger share of their bill simply for being connected. Compare a low fixed charge plan if the household uses under 8,000 kWh a year: those regulations are capped at $1.80 a day from 1 April 2026 and are revoked on 1 April 2027.",
    "nz_average_rate": 39.3,
    "rate_cents_per_kwh": 38.5,
    "rate_source": "MBIE QSDEP, February 2026, auckland, including GST",
    "region": "auckland",
    "regions_compared": 24,
    "saving_against_most_expensive": 1191.96
  }
}

Changes

No recorded changes to this operation across all 1 revision of this API.