Factorio Saturate Yellow Belt

In Factorio, mastering logistics is crucial to building a highly efficient factory. One key aspect of logistics is understanding how to fully saturate a yellow belt the most basic of the game’s three main transport belts. While it may seem simple at first, saturating a yellow belt efficiently requires thoughtful planning, balanced production, and precise placement of inserters and machines. Players aiming to optimize their factories often need to learn not just how much to produce, but how to move items through the belts in a way that maintains consistent throughput and avoids congestion or gaps. This makes yellow belt saturation a foundational concept in Factorio’s complex supply chain.

Understanding the Yellow Belt

Base Properties of the Yellow Belt

The yellow belt is the first type of conveyor belt you gain access to in Factorio. It moves items at a speed of 15 items per second per lane, totaling 30 items per second when both lanes are fully saturated. Compared to red and blue belts, the yellow belt has the slowest speed, which makes saturation more challenging when dealing with high-throughput production lines.

When to Use Yellow Belts

Despite being the slowest, yellow belts are still very effective in the early and mid-game stages. They are cheap to produce, require minimal materials, and are suitable for basic material transportation like iron plates, copper, coal, and circuits before your factory’s demand exceeds their capacity.

What It Means to Saturate a Yellow Belt

Saturation Defined

Saturating a yellow belt means filling both sides of the belt consistently with no gaps between items, so it can deliver the maximum number of items per second. This ensures your production lines have a constant supply of inputs, reducing idle time and improving overall efficiency. A properly saturated belt can feed assemblers or furnaces continuously without starving them of resources.

Importance of Full Belt Utilization

Having a fully saturated belt helps avoid bottlenecks. It means your upstream production and inserters are balanced and producing at a rate that perfectly matches the belt’s capacity. This balance is key in large-scale factories where underutilized belts can cause downstream inefficiencies and delays in production.

How to Saturate a Yellow Belt Effectively

1. Know Your Production Rates

Start by calculating how many items per second your machines can produce. For example, a stone furnace producing iron plates from iron ore has a crafting time of 3.2 seconds and yields 1 plate. To saturate one side of a yellow belt (15 items per second), you would need 48 furnaces. For both sides, you would need 96.

2. Balanced Inputs from Both Sides

You can saturate both lanes of a belt by placing inserters on each side or using techniques such as:

• Double-sided inserter placement from parallel machines.
• Underground belts and splitters to evenly load both lanes.
• Balanced bus feeding with output inserters offsetting to both sides.

3. Use Splitters Wisely

Splitters are powerful tools for achieving lane balancing. A basic splitter divides items evenly across two output belts, which can then be merged back into a single belt. To saturate a yellow belt, use splitters to combine outputs from multiple production lines in a way that fills both lanes equally.

4. Merging and Lane Balancing

If you’re combining belts, make sure the merge maintains throughput. Improper merging can cause one lane to overflow while the other remains underused. Use lane balancers or priority splitters to guarantee fair distribution and continuous flow.

Example: Saturating a Yellow Belt with Iron Plates

Iron Smelting Calculation

Let’s assume you want to saturate a yellow belt with iron plates using stone furnaces. As mentioned, each stone furnace produces 0.3125 iron plates per second. To achieve 30 plates per second (full saturation), divide 30 by 0.3125. This gives you 96 furnaces.

Practical Furnace Layout

Place 48 furnaces on each side of the belt, with inserters placing the output directly onto the belt. Ensure coal and ore inputs are steady and split evenly. You may need a balancer for your iron ore supply and coal to avoid side overloads.

Power and Inserter Timing

Inserters must be powered and fast enough to keep up. Burner inserters might be too slow; electric inserters are more reliable. Also, make sure your power network can handle the demand from nearly 100 furnaces running simultaneously.

Tips to Maintain Yellow Belt Saturation

Monitor Belt Gaps

Gaps in belts often indicate inconsistent production or inserter delays. Watch your belts during operation. If gaps form over time, check your input sources, inserter placement, and machine speed. A truly saturated belt should have a constant flow without irregular spacing.

Avoid Backups

If a downstream machine stops working or is full, your belt can back up. When that happens, the upstream machines stop producing, breaking the saturation cycle. Make sure the end of the belt has room for items to be used or stored continuously.

Upgrade When Necessary

Eventually, your factory will grow beyond the limits of yellow belts. Once you need more than 30 items per second, consider upgrading to red (30 items per lane, 60 total) or blue belts (45 per lane, 90 total). Saturating a yellow belt is still a good exercise in logistics discipline and base setup for more advanced tiers.

Advanced Saturation Techniques

Direct Insertion Alternatives

While belts are a visual and intuitive method, sometimes direct insertion (machine to machine) is more efficient and requires less belt space. This won’t help saturate a belt but may be useful in stages where saturation isn’t necessary.

Buffer Chests and Smart Inserters

Use buffer chests with filter or stack inserters if your production is uneven. Chests can absorb excess production and release it slowly to maintain saturation over time, especially useful for builds with fluctuating input.

Saturating a yellow belt in Factorio isn’t just about cramming items onto a belt it’s about understanding the flow of resources, the rate of production, and how different components of your factory interact. From calculating the number of machines needed to strategically placing inserters and balancing lanes, every detail contributes to efficient belt saturation. Mastering yellow belt logistics prepares you for more complex systems and larger-scale builds. It teaches you the core principles of throughput, balance, and efficiency that are central to the entire game. Whether you’re designing your first smelting line or setting up a full bus, saturating your yellow belts is a satisfying and rewarding part of the Factorio experience.