Coal Stocks Follow a Price Index Most Investors Never Look At. Here's How HBA Works
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5 min read
On 1 October 2026, Indonesia's government set the top-grade coal reference price at US$122.52 per tonne. Two months earlier, in early August, the same grade was set at US$124.44.
Most people who own Indonesian coal stocks have never looked at that number. They watch Newcastle futures or the daily share price. But the number has a rule behind it, and that rule touches what coal miners pay and what they can charge.
It is called HBA, short for Harga Batu Bara Acuan, or "coal reference price". This post explains it in plain words.
HBA is a price the Ministry of Energy and Mineral Resources (ESDM) publishes for Indonesian coal. It is not a market price you can trade. It is a reference: a number the government says is a fair benchmark for a given grade of coal.
Coal comes in grades, based on how much energy it holds. That energy is measured in kcal/kg GAR (kilocalories per kilogram, "gross as received"). More energy means a higher price.
ESDM publishes several HBA numbers at once. For the first period of October 2026, these were reported:
| Category | Energy level (kcal/kg GAR) | HBA, 1 Oct 2026 |
|---|---|---|
| HBA | 6,322 | US$122.52 per tonne |
| HBA I | 5,300 | US$90.60 per tonne |
| HBA II | 4,100 | US$63.45 per tonne |
Sources: Ministerial Decree No. 384.K/MB.01/MEM.B/2026, as reported by Indonesian business media in search summaries retrieved on 6 October 2026. A fourth category, HBA III, is also published, but we could not confirm its October figure, so we leave it out.
Notice the gap. The top grade is almost twice the price of the low grade. Many Indonesian mines produce the lower grades.
HBA used to be set once a month. In 2026 it is published twice a month, on the 1st and the 15th. Each one is called a "period".
The formula was revised in 2023. Reports from that revision say HBA is based on the average selling price of coal in the earlier period. In plain words: it follows what coal has actually sold for, with a short delay. It is not a forecast.
That delay matters. When the market moves fast, HBA catches up one period later.
Many investors follow Newcastle coal futures. These are contracts traded on an exchange, based on coal delivered at the Australian port of Newcastle. It is a global price for a high-grade coal.
HBA is different in three ways:
The two prices often move in the same direction. They are rarely equal. We did not find one reliable Newcastle quote for the same day, since data feeds disagreed, so we do not compare the two in numbers here.
Since 1 March 2025, Indonesian coal exporters have to use HBA as the reference for export sales. This comes from Ministerial Decree No. 72.K/MB.01/MEM.B/2025. Before that, sellers often used other indices, such as the Indonesia Coal Index (ICI) or Newcastle.
Here is what the rule does:
A royalty is a share of sales value paid to the government for taking its resources out of the ground. When the benchmark rises, the royalty base rises with it.
Reports at the time said some Chinese buyers objected to using HBA for exports. The rule remained in force.
Here is the simple chain:
Two examples of what this does not say. It does not say a coal stock will rise when HBA rises. Share prices already react to news, and many other things matter: volumes, costs, debt, dividends and government policy.
It also does not tell you which company is better. A miner selling mostly low-grade coal feels the HBA II line. A miner selling high-grade coal feels the top line.
One caution on tickers. ADRO is no longer the thermal coal business it was before 15 January 2026. That business moved into a separate listed company, AADI, so be careful with older articles that describe ADRO as a pure coal miner. Bukit Asam (PTBA) was not part of that split.
Next time ESDM publishes a new period, check three things:
Then compare with the company's own report. The report tells you what price it actually got.
Open the PTBA asset page and scroll through its price history. Then compare its big moves against the HBA announcements above. You will see which swings follow coal prices and which come from something else, like dividends or company news.