Base Design — factorio Layout & Architecture

Base Design in Factorio

A great factory isn't just about producing items — it's about producing them in a way that's organized, expandable, and repairable. Base design is the art of organizing production chains spatially.

Main Bus Architecture

The main bus is the most popular mid-game factory architecture. A set of parallel bus lanes runs down the center of the factory, and each production line pulls from the bus.

What Goes on the Main Bus (in order)

1. Iron plates — 2 to 4 lanes
2. Copper plates — 1 to 2 lanes
3. Gears — 1 lane
4. Electronic circuits (green) — 1 lane
5. Steel plates — 1 lane
6. Advanced circuits (red) — 1 lane
7. Plastic bars — 1 lane

Bus Width Recommendations

• Iron: 4 lanes minimum (you'll need it for green circuits + gears + blue science)
• Copper: 2 lanes minimum (green circuits + red circuits)
• Gears: 1 lane (very low total consumption)
• Green circuits: 1 lane (high consumption, but compact)

When NOT to Use a Main Bus

• When you need to ship items backward up the factory (bus only works for forward flow)
• When you want absolute UPS efficiency (bus architectures have dead walking sections)
• When playing Space Age — Gleba and Fulgora require completely different layouts

City Block Design

City blocks are the gold standard for large and megabase builds. Each block is a uniform square (e.g., 64x64 tiles), and every production facility fits inside a block.

Advantages of City Blocks

• Uniform layout = easy to expand
• Trains can navigate using the same intersections
• Simple to copy/paste with blueprints
• Easy to calculate throughput per block

Standard Block Sizes

• 64x64 — popular for vanilla megabases
• 48x48 — tighter, more compact
• 32x32 — for tighter resource areas

Main Bus + City Block Hybrid

Many players use a main bus for early/mid game, then transition to city blocks for late game megabase builds.

Smelting Setups

Stone vs. Steel vs. Electric Furnaces

Smelting Array Ratios

• 12 steel furnaces on a full yellow belt of ore = 1 full yellow belt of plates
• 12 electric furnaces = same output, zero fuel management
• 24 electric furnaces = 2 full belts of plates

Nuclear Power Layouts

Nuclear is more complex than steam but produces 25x more power per building.

Basic Nuclear Setup

• 1 Reactor produces 40 MW of heat
• Reactors can be adjacent — each neighbor adds 100% bonus heat exchange
• 2-reactor adjacent = 120 MW total (each reactor 60 MW effective)
• N-reactor row: (N × 40) + ((N-1) × 40) MW effective

Kovarex Enrichment

A single Kovarex loop (2 centrifuges with 5% productivity) sustains unlimited nuclear fuel once started.

Beacon & Module Setups

Speed Beacon Layout

• 8 beacons per assembler (optimal) — beacons on all 8 adjacent tiles
• Speed Module 3 in both beacons and assembler: 700% base speed
• 1 beaconed blue circuit assembler = ~10 unbeaconed assemblers in terms of output

Productivity Beacon Layout

• 8 beacons with Productivity Module 3
• Reduces total packs needed by 30% per tier
• Essential for reducing the scale of high-tier science (purple, yellow, space)

Mixed Setup (Speed + Productivity)

• Beacons have 2 module slots — can mix Speed 3 + Productivity 3
• Most efficient late-game setup: 4 Speed 3 + 4 Productivity 3 per beacon

Megabase Layouts

A megabase produces 1,000+ SPM (science per minute). The architecture matters enormously for UPS (updates per second).

UPS-Friendly Designs

• Beacon-strip layouts: Production lines in rows with beacons between
• Balancer-based city blocks with train throughput matching production
• Bot-based megabases: Less UPS-efficient but simpler to build

SPM Calculation

• 1 SPM = 1 of each science pack per minute
• 1,000 SPM requires roughly 5,000 assembling machine 3s (unbeaconed)
• With heavy beaconing: 1,000 SPM can be achieved with ~500 assemblers

Expandable Base Guide

The number one rule: Design your first factory assuming you'll want to expand it.

Signs your base is getting cramped:

• Green circuit production can't keep up with demand
• Your bus has more splitters than lanes
• You can't find space to add a new production line

When to rebuild:

• Once your first green circuit line is full, plan a second before adding blue science
• The moment biters start eating your production lines, redesign the defense

Related Guides

• Main Bus Guide — Full bus architecture walkthrough
• Beacon Setup Guide — Module and beacon math
• City Block Guide — Uniform megabase tiles
• Nuclear Setup Layout — Full reactor blueprints