Reserves & Resources

We have a strong track-record of increasing Mineral Reserves and Resources through exploration.

Mineral Reserves of 5.83 Moz gold

Proven + Probable Mineral Reserves (as at Dec 31, 2025)

M&I Resources of 8.63 Moz gold

Measured & Indicated Mineral Resources (as at Dec 31, 2025)

Inferred Resources of 2.5 Moz gold

Inferred Mineral Resources (as at Dec 31, 2025)

Mineral Reserves

Our Proven and Probable Mineral Reserves estimates are presented in Table 1 below.

Table 1: Proven and Probable Reserves as at December 31, 2025

	Proven			Probable			Proven & Probable
	Tonnes	Au	Contained	Tonnes	Au	Contained	Tonnes	Au	Contained
Gold	(Mt)	(g/t)	Ozs (Moz)	(Mt)	(g/t)	Ozs (Moz)	(Mt)	(g/t)	Ozs (Moz)	Cut-off grade
Horseshoe Underground	1.52	4.39	0.21	2.63	4.24	0.36	4.14	4.29	0.57	1.86 g/t Au
Palomino Underground	–	–	–	3.62	2.96	0.34	3.62	2.96	0.34	1.86 g/t Au
Ledbetter Underground	–	–	–	4.00	3.39	0.44	4.00	3.39	0.44	1.86 g/t Au
Open Pits	2.47	1.23	0.10	16.1	1.62	0.84	18.6	1.57	0.94	0.50 g/t & 0.60 g/t Au
Haile Total	3.99	2.43	0.31	26.3	2.33	1.98	30.3	2.35	2.29
Didipio underground	13.5	1.39	0.60	14.7	0.85	0.40	28.3	1.11	1.01	0.76 g/t & 1.16 g/t AuEq
Didipio open pit stockpile	13.2	0.30	0.13	–	–	–	13.2	0.30	0.13	0.27 g/t AuEq
Didipio Total	26.7	0.85	0.73	14.7	0.85	0.40	41.5	0.85	1.13
Macraes underground	0.04	2.01	0.00	2.57	1.90	0.16	2.62	1.90	0.16	1.08 g/t & 0.94 g/t Au
Macraes open pits	11.5	0.55	0.20	19.70	0.64	0.40	31.2	0.61	0.61	0.25 g/t & 0.30 g/t Au
Macraes Total	11.5	0.56	0.21	22.3	0.78	0.56	33.8	0.71	0.77
Martha underground	–	–	–	3.43	3.85	0.42	3.43	3.85	0.42	2.6 g/t & 3.2 g/t Au
Wharekirauponga	–	–	–	4.10	9.20	1.21	4.10	9.20	1.21	2.40 g/t Au
Waihi Total	–	–	–	7.53	6.76	1.64	7.53	6.76	1.64
Total Gold	42.3	0.92	1.25	70.9	2.01	4.58	113	1.60	5.83

	Proven			Probable			Proven & Probable
Silver	Tonnes	Ag	Contained	Tonnes	Ag	Contained	Tonnes	Ag	Contained
Silver	(Mt)	(g/t)	Ozs (Moz)	(Mt)	(g/t)	Ozs (Moz)	(Mt)	(g/t)	Ozs (Moz)
Horseshoe Underground	1.52	1.5	0.1	2.63	1.8	0.2	4.14	1.7	0.2
Palomino Underground	–	–	–	3.62	2.7	0.3	3.62	2.7	0.3
Ledbetter Underground	–	–	–	4.00	11	1.3	4.00	11	1.3
Open Pits	2.47	2.1	0.2	16.1	2.3	1.2	18.6	2.2	1.3
Haile Total	3.99	1.9	0.2	26.3	3.5	3.0	30.3	3.3	3.2
Didipio underground	13.5	1.7	0.7	14.7	1.3	0.6	28.3	1.5	1.4
Didipio open pit stockpile	13.2	1.9	0.8	–	–	–	13.2	1.9	0.8
Didipio Total	26.7	1.8	1.6	14.7	1.3	0.6	41.5	1.7	2.2
Martha underground	–	–	–	3.43	17	1.9	3.43	17	1.9
Wharekirauponga	–	–	–	4.10	16	2.1	4.10	16	2.1
Waihi Total	–	–	–	7.53	17	4.0	7.53	17	4.0
Total Silver	30.7	1.8	1.8	48.6	4.9	7.6	79.3	3.7	9.5

	Proven			Probable			Proven & Probable
	Tonnes	Cu	Contained	Tonnes	Cu	Contained	Tonnes	Cu	Contained
Copper	(Mt)	(%)	(Mt)	(Mt)	(%)	(Mt)	(Mt)	(%)	(Mt)
Didipio underground	13.5	0.38	0.05	14.7	0.31	0.05	28.3	0.35	0.10
Didipio open pit stockpile	13.2	0.28	0.04	–	–	–	13.2	0.28	0.04
Didipio Total	26.7	0.33	0.09	14.7	0.31	0.05	41.5	0.32	0.13
Total Copper	26.7	0.33	0.09	14.7	0.31	0.05	41.5	0.32	0.13

Notes:

Mineral Reserves are defined by mine designs based upon the following assumptions: metal prices of US$2,200/oz gold, US$4.00/lb copper and US$25/oz silver; NZD/USD exchange rate of 0.60.
Reported estimates of contained metal are not depleted for processing losses.
For underground reserves, cut-offs applied to diluted grades.
Mineral Reserves are reported on a 100% basis. OceanaGold holds an 80% attributable interest in the Didipio Mine.

Haile:

Open Pit: the primary cut-off grade is 0.5 g/t Au, while oxide material is assigned a cut-off grade of 0.6 g/t Au.
Underground: the cut-off grade is 1.86 g/t Au.

Didipio:

Gold equivalence (AuEq) is based upon the presented gold and copper prices as well as processing recoveries. AuEq = Au g/t + 1.27 x Cu%.
The 13.2 Mt surface stockpile inventory includes 5.3 Mt of low-grade stocks mined at an approximate cut-off grade of 0.27 g/t AuEq.
Underground: cut-off grade of 1.16 g/t AuEq is used. Incremental stopes proximal to development already planned to access main stoping areas are reported to a lower cut-off grade of 0.76 g/t AuEq

Macraes:

Open Pit: Primary cut-off grade is 0.25 g/t while Golden Bar is 0.30 g/t
Underground: Golden Point cut-off grade is 1.08 g/t Au. Stopes for which access already exists are reported to a lower cut-off grade of 0.94 g/t.

Waihi:

Martha Underground cut-off grade for previously unmined stoping areas is 2.60 g/t Au, increasing to 3.2 g/t Au for stoping areas in close proximity to remnant workings.
Wharekirauponga Underground cut-off grade for stopes is 2.40 g/t Au.

Mineral Resources

Our Measured, Indicated and Inferred Mineral Resource estimates (inclusive of Mineral Reserves) are presented in Table 2 below.

Table 2: Measured and Indicated Resources as at December 31, 2025

	Measured			Indicated			Measured & Indicated			Inferred
	Tonnes	Au	Contained	Tonnes	Au	Contained	Tonnes	Au	Contained	Tonnes	Au	Contained
Gold	(Mt)	(g/t)	(Moz)	(Mt)	(g/t)	(Moz)	(Mt)	(g/t)	(Moz)	(Mt)	(g/t)	(Moz)	Cut-off grade
Horseshoe Underground	1.98	5.11	0.33	2.76	5.11	0.45	4.74	5.11	0.78	0.5	2.7	0.0	1.70 g/t Au
Palomino Underground	–	–	–	4.19	3.38	0.45	4.19	3.38	0.45	0.8	2.5	0.1	1.70 g/t Au
Ledbetter Underground	–	–	–	4.07	4.12	0.54	4.07	4.12	0.54	1.2	2.9	0.1	1.70 g/t Au
Open Pits	2.58	1.21	0.10	16.1	1.64	0.85	18.7	1.58	0.95	0.6	0.9	0.0	0.50 g/t & 0.60 g/t Au
Haile Total	4.56	2.91	0.43	27.1	2.63	2.30	31.7	2.67	2.72	3.1	2.4	0.2
Didipio Underground	14.3	1.53	0.71	17.7	0.89	0.51	32.0	1.18	1.21	9.2	0.9	0.3	0.67 g/t AuEq
Open Pit Stockpiles	13.2	0.29	0.12	–	–	–	13.2	0.29	0.12	–	–	–	0.27 g/t & 0.40 g/t AuEq
Didipio Total	27.5	0.94	0.83	17.7	0.89	0.51	45.2	0.92	1.34	9.2	0.9	0.3
Macraes Underground	0.08	3.02	0.01	6.37	2.28	0.47	6.45	2.29	0.47	2.4	1.8	0.1	0.97 g/t Au
Open Pits	12.6	0.62	0.25	35.7	0.67	0.76	48.3	0.65	1.01	25	0.7	0.5	0.25 g/t & 0.40 g/t Au
Macraes Total	12.7	0.63	0.26	42.1	0.91	1.23	54.8	0.85	1.49	27	0.8	0.7
Martha Underground	–	–	–	6.33	5.24	1.07	6.33	5.24	1.07	2.2	4.6	0.3	2.15 g/t Au
Wharekirauponga	–	–	–	2.63	17.3	1.46	2.63	17.3	1.46	2.9	8.5	0.8	1.70 g/t Au
Open Pits	–	–	–	9.72	1.78	0.56	9.72	1.78	0.56	3.2	1.8	0.2	0.50 g/t & 0.56 g/t Au
Waihi Total	–	–	–	18.7	5.13	3.08	18.7	5.13	3.08	8.3	4.9	1.3
Total Gold	44.8	1.05	1.51	106	2.10	7.11	150	1.78	8.63	48	1.6	2.5

	Measured			Indicated			Measured & Indicated			Inferred
	Tonnes	Ag	Contained	Tonnes	Ag	Contained	Tonnes	Ag	Contained	Tonnes	Ag	Contained
Silver	(Mt)	(g/t)	(Moz)	(Mt)	(g/t)	(Moz)	(Mt)	(g/t)	(Moz)	(Mt)	(g/t)	(Moz)
Horseshoe Underground	1.98	1.9	0.12	2.76	2.1	0.2	4.7	2.0	0.3	0.5	1.0	0.02
Palomino Underground	–	–	–	4.19	2.8	0.4	4.2	2.8	0.4	0.8	2.1	0.06
Ledbetter Underground	–	–	–	4.07	12.5	1.6	4.1	12.5	1.6	1.2	7.5	0.28
Open Pits	2.58	2.2	0.18	16.1	2.5	1.3	19	2.4	1.5	0.6	2.4	0.0
Haile Total	4.56	2.0	0.30	27.1	4.0	3.5	32	3.7	3.8	3.1	4.0	0.4
Didipio Underground	14.3	1.8	0.8	17.7	1.4	0.8	32.0	1.6	1.6	9.2	1.2	0.4
Open Pit Stockpiles	13.2	1.9	0.8	–	–	–	13.2	1.9	0.8	–	–	–
Didipio Total	27.5	1.8	1.6	17.7	1.4	0.8	45.2	1.7	2.4	9.2	1.2	0.4
Martha Underground	–	–	–	6.33	20	4.1	6.3	20	4.1	2.2	24	1.7
Wharekirauponga	–	–	–	2.63	27	2.3	2.6	27	2.3	2.9	13	1.2
Open Pits	–	–	–	9.72	10	3.2	9.7	10	3.2	3.2	9.6	1.0
Waihi Total	–	–	–	18.7	16	9.6	19	16	9.6	8.2	15	3.9
Total Silver	32.1	1.85	1.9	63.5	6.8	14	96	5.1	16	20	7.1	4.7

	Measured			Indicated			Measured & Indicated			Inferred
Copper	Tonnes	Cu	Contained	Tonnes	Cu	Contained	Tonnes	Cu	Contained	Tonnes	Cu	Contained
	(Mt)	(%)	(Mt)	(Mt)	(%)	(Mt)	(Mt)	(%)	(Mt)	(Mt)	(%)	(Mt)
Didipio Underground	14.3	0.43	0.06	17.7	0.33	0.06	32.0	0.37	0.12	9.2	0.3	0.02
Open Pit Stockpiles	13.2	0.28	0.04	-	-	-	13.2	0.28	0.04	-	-	-
Didipio Total	27.5	0.36	0.10	17.7	0.33	0.06	45.2	0.35	0.16	9.2	0.3	0.02
Total Copper	27.5	0.36	0.10	17.7	0.33	0.06	45.2	0.35	0.16	9.2	0.3	0.02

Notes:

Mineral Resources are reported inclusive of Mineral Reserves. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.
All resources are based on the following assumptions: metal prices of US$2,450/oz gold, US$4.50/lb copper and US$28.50/oz silver; NZD/USD exchange rate of 0.60.
Macraes Open Pit resources are constrained by optimised shells based upon economic assumptions above. Waihi Open Pit resources reported within a pit design limited by infrastructural considerations. Haile Open Pit resources reported within the reserve design pit.
Underground resources are reported within volumes guided by conceptual stope designs which are based upon economic assumptions above and exclude dilution.
Mineral Resources are reported on a 100% basis. OceanaGold holds an 80% attributable interest in the Didipio Mine.

Haile:

Open Pit primary cut-off grade is 0.50 g/t Au, while oxide cut-off grade is 0.60 g/t Au. Horseshoe, Ledbetter and Palomino underground resources at 1.70 g/t Au cut-off.

Didipio:

13.2 Mt surface stockpile inventory based on mining cut-off grades at the time ranging from 0.27 g/t to 0.40 AuEq.
Underground resources reported at a cut-off grade of 0.67 g/t AuEq between the 2,460mRL and 1,800mRL with AuEq cut-off grade based on presented gold and copper prices. AuEq = Au g/t + 1.27 x Cu %.

Macraes:

Open Pits cut-off grades between 0.25 g/t Au and 0.40 g/t Au.
Golden Point underground cut-off grade is 0.97 g/t Au.

Waihi:

Martha underground cut-off grade is 2.15 g/t Au, Wharekirauponga cut-off grade is 1.70 g/t Au.
Martha Open Pit cut-off grade is 0.5 g/t Au and Gladstone Open Pit cut-off grade is 0.56 g/t Au.