how many coal ores to make 820 rune bars blast furnace

To make 820 rune bars at the Blast Furnace in Old School RuneScape, you’ll need 820 rune ores and 3,280 coal (because rune bars require an 8:1 coal-to-ore ratio, and the Blast Furnace halves the coal needed).

How the math works

Standard smelting ratio for rune bars

• Normally, 1 rune bar = 1 rune ore + 8 coal.

Blast Furnace effect

• The Blast Furnace halves the coal requirement for smelting bars.

• So at the Blast Furnace:
  1 rune bar = 1 rune ore + 4 coal

Calculation for 820 rune bars

• Rune ore needed: 820 × 1 = 820 rune ores
• Coal needed: 820 × 4 = 3,280 coal

TL;DR: 820 rune ores + 3,280 coal → 820 rune bars at the Blast Furnace.

Practical tips for efficient runs

If you’re batching this over multiple trips, here’s a common setup many players use:

• Use a coal bag to carry extra coal per trip.
• Typical efficient cycle:
  1. Bring 2 inventories of coal + fill coal bag.
  2. Deposit coal at the conveyor belt.
  3. Bring rune ore + more coal (or just ore if you’ve stockpiled enough coal).
  4. Smelt, collect bars, repeat.

This minimizes back-and-forth while keeping the furnace fed.

Sources

Information gathered from public forums or data available on the internet and portrayed here.