These charts follow the weekly prices for crude oil, New Zealand pump prices for unleaded 91 petrol and automotive diesel, as well as the amount of the retail petrol price that is tax, and the oil company margin.

The data is sourced from the Ministry of Economic Development weekly series for petroleum products.

The crude oil price is based on the Dubai benchmark, as the Dubai market is the most common source of crude oil for New Zealand.

There are 159 litres per barrel.

The New Zealand petrol and diesel retail prices in these charts are based on limited monitoring of service station forecourt prices by the MED. As such, they will not reflect all the variation due to regional pricing differences and discounts available to bulk diesel customers.

The amount of tax on unleaded 91 petrol includes GST, excise tax that goes straight into the Crown bank account, the National Land Transport Management Fund, the ACC levy, the Petroleum or Engine Fuel Monitoring Levy, and the local authorities fuel tax. The ETS charge of about 3c/litre came into effect on October 1, 2010. GST also rose at the same time from 12.5% to 15%, and this increase compounded the ETS rise.

The "oil company component", is the net fuel price after excluding the crude oil price and taxes. It covers the costs of importing, refining, and distribution to the pump. The MED wants you to know that this is a different approach to the one they use to calculate "margin". See their website to find their more intricate definition.

The cost of crude oil we buy on international markets has fluctuated markedly over the past 30 years, even more so in NZ$, but the inflation-adjusted cost ("real" cost) shows we have benefited from a long period of relatively low costs.

Contact us for the data that drives this chart.