Getting Your Furnace Up and Running
The furnace is one of those early-game tools you build almost by accident. You chop some wood, punch up some copper ore from a rock in the mountains, and figure out you can make a hammer. From there it's a straightforward recipe: 50 coal and 20 copper bars. I know, that's a lot of copper for someone who just started two days ago. Don't bother smelting it yourself at first. Just use the existing furnaces in town or buy a few from Robin when she offers them for gold. Smelting in Stardew Valley is brutally simple at its core. You put ore in the top slot and coal in the bottom slot, then wait. Copper ore becomes copper bars. Iron ore becomes iron bars. Gold ore becomes gold bars. Obsidian becomes glass. The process takes 8 in-game hours for most metals, though gold takes longer and obsidian takes even more. Here's where people mess up. You need exactly one coal per item you're smelting. There's no efficiency bonus for using high-quality coal. Regular coal works fine. I spent like ten minutes one evening trying to find a way to make my furnace run faster after reading some forum thread about "optimized smelting" and there was nothing. It just runs at its speed. Period.
The real trick is managing your coal supply before you start a batch. I once ran out of coal halfway through smelting a stack of twenty iron ore bars and had to spend two whole evenings just chopping trees and making more. Don't be that person. Always have at least double the coal you think you need.
Where to Find the Raw Materials
Copper ore spawns in the mines on floors 1 through 39. Iron ore appears on floors 40 through 79. Gold ore is floors 80 through 119. Coal comes from killing skeletons in the mines or breaking certain rocks outside during summer. You also get small amounts of coal from mining geodes at the blacksmith. The mines are the biggest bottleneck for new players. If you're struggling to get through, bring headgear with night vision enabled. Skulls drop coal fairly consistently from floor 40 onward, but they're also the point where enemies get significantly harder. I typically stock up on coal during my first week by farming the lower mine levels and killing every skeleton I see, even when I'm deep in combat. It pays off later.
Get the Full Details
Advanced Smelting Considerations
Most guides stop at basic ore smelting. They don't mention that you can also smelt golden ore into gold bars using regular coal, not special coal or any variant. The game doesn't care. It's just 1 ore + 1 coal = 1 bar, regardless of quality or type. Another thing nobody talks about: the furnace has a queue system. You can load multiple items at once and they process sequentially. This means you can set up a batch of copper, then iron, then gold without touching your computer for several hours. The total time is additive though, so twenty gold bars will take roughly 5 in-game days to complete at standard speed. Here's a counter-intuitive detail: if you have a spring onion or other quick-action crop ready to harvest, plant it near your furnace before starting a long smelt cycle. You can check on your crops and collect resources without interrupting the furnace. I learned this the hard way after watching my furnace sit idle for six hours because I kept going back to check my crops in Pelican Town.
Common Pitfalls
The biggest mistake I see is players trying to smelt ore they don't have enough of to make anything useful. A single iron bar doesn't help anyone. You need at least ten to make an upgrade tool, and twenty for an axe. Plan your batches around what you actually need to craft, not what you happen to have collected. Another issue is forgetting that the furnace needs to be placed on the ground, not inside your house. It works fine outside, but if you put it in a room without proper flooring it won't operate. I've seen players spend twenty minutes trying to figure out why their indoor furnace isn't working before realizing they hadn't cleared the debris from under it. There's also a cooldown period after smelting completes. The furnace takes about 30 seconds to reset between batches. If you're constantly loading and unloading items, this adds up. I recommend loading a full batch and letting it run rather than managing individual items.
When to Skip the Furnace Entirely
If you're early game and only need a handful of bars for basic tools, it might be faster to just buy them from the blacksmith. One iron bar costs 50 gold. Twenty bars cost 1,000 gold. If you're struggling to afford that, consider focusing on farming first and building your mine clearance before investing heavily in smelting infrastructure. For obsidian specifically, consider whether you actually need glass before going through the effort. Glass requires 10 obsidian and takes over an in-game day. That's a massive time investment for something you might only use once for a specific craft. Make sure you have a clear purpose before committing.
The Bottom Line
Smelting in Stardew Valley is straightforward once you understand the timing and resource requirements. The game doesn't reward optimization or cleverness here. It rewards planning ahead, managing your coal supply, and batching your smelts efficiently. Build a few furnaces, stockpile your coal, and let the game do its thing while you focus on other activities.
