"The forecast impact of this, assuming an oil price of $100 per barrel, is between $40 to $50 per ounce on a portfolio level," it said in a quarterly update.
Gold Fields did not change its cost guidance for the year, however, saying measures, such as more fuel-efficient, high-capacity haulage systems at its mines, should contain costs.
The gold mining company, which has operations in South Africa, Ghana, Australia, Chile and Peru, said its biggest cost increase was for diesel, which has risen by up to 70%.
Freight costs have risen 40%, and liquefied natural gas, which Gold Fields uses to power its remote mining operations at sites such as Agnew mine in Western Australia, has gone up by 30%.
Other increases include 10% rises in the cost of both explosives and cyanide, a chemical produced from petrochemical feedstocks such as natural gas and used in gold processing.
After the US and Israel launched airstrikes on Iran at the end of February 28, unleashing a wider conflict and unprecedented energy supply disruption, international crude futures LCOc1 rose to a peak around $126 at the end of April.
They slipped below $100 a barrel, as US President Donald Trump has talked up the prospect of peace, but they remain much higher than at the start of the year.
Gold prices, which hit a record around $5,595 an ounce at the end of January, have been volatile and have pulled back to current levels around $4,744 an ounce.
The miner produced 633,000 ounces of gold during the first quarter of 2026, 15% higher compared to the same period last year, as its ramp-up of the Salares Norte mine in Chile offset lower output at the Tarkwa mine in Ghana, as well as Agnew and Gruyere mines in Australia.
Gold Fields expects to produce between 2.4 million ounces and 2.6 million ounces of gold in 2026.
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