How to Choose Between CM4 Variants: eMMC vs Lite, WiFi vs No WiFi

Picking the right Raspberry Pi Compute Module 4 variant shouldn’t require a flowchart and three cups of coffee, but here we are. With 32 different CM4 variants on the market, engineers face a genuine decision matrix when speccing out embedded projects.

I’ve made this choice dozens of times across industrial control systems, digital signage deployments, and prototype runs. The difference between selecting a CM4108032 versus a CM4008032 might seem trivial on paper, but it cascades through your BOM costs, carrier board design, and field serviceability.

This guide breaks down the CM4 variants decision with real engineering tradeoffs—not marketing speak.

Understanding CM4 Variant Naming Convention

The CM4 part numbers follow a logical structure that encodes every key specification. Once you crack the code, ordering becomes straightforward.

CM4 Part Number Breakdown

Position	Meaning	Options
CM4	Base model	Always “CM4”
1st digit	Wireless	0 = No WiFi, 1 = WiFi/BT
2nd digit	RAM (GB)	01, 02, 04, 08
3rd-4th digits	eMMC (GB)	00 (Lite), 08, 16, 32

So when you see CM4108032, you’re looking at a CM4 with WiFi (1), 8GB RAM (08), and 32GB eMMC (032). Meanwhile, CM4008032 is identical except it lacks wireless connectivity (0 instead of 1).

The “Lite” designation applies to any variant with “00” in the eMMC position—these modules have no onboard storage and require a microSD card on the carrier board.

Complete CM4 Variants Pricing Reference

Part Number	Wireless	RAM	eMMC	Price (USD)
CM4001000	No	1GB	Lite	$30
CM4001008	No	1GB	8GB	$35
CM4001016	No	1GB	16GB	$40
CM4001032	No	1GB	32GB	$45
CM4002000	No	2GB	Lite	$40
CM4002032	No	2GB	32GB	$55
CM4004000	No	4GB	Lite	$55
CM4004032	No	4GB	32GB	$70
CM4008000	No	8GB	Lite	$80
CM4008032	No	8GB	32GB	$95
CM4101000	Yes	1GB	Lite	$35
CM4104000	Yes	4GB	Lite	$60
CM4108000	Yes	8GB	Lite	$85
CM4108032	Yes	8GB	32GB	$100

Prices reflect 2025 MSRP and may vary by distributor.

eMMC vs Lite: The Storage Decision

This is typically the first fork in your decision tree, and it has the most significant implications for your carrier board design.

Why Choose CM4 with eMMC

The eMMC variants (8GB, 16GB, or 32GB) integrate flash storage directly on the module. From a PCB engineer’s perspective, this simplifies carrier board design considerably.

Performance advantages of eMMC:

The CM4’s eMMC uses an 8-bit bus interface, delivering roughly 2x the read performance and 3x the write performance compared to typical microSD cards. In benchmarks, the CM4 eMMC achieves around 83-90 MB/s sequential read speeds—competitive with good microSD cards but with significantly better random I/O performance.

For applications involving frequent small file operations (database queries, logging, configuration reads), eMMC’s random I/O advantage matters more than raw sequential throughput.

Reliability considerations:

Industrial deployments favor eMMC because there’s no removable media to work loose from vibration, no card to corrupt from unexpected power loss, and no slot mechanism to wear out over thousands of insertion cycles. The eMMC is soldered to the module—it goes nowhere.

When eMMC makes sense:

• Production deployments where the OS image is finalized
• Vibration-prone environments (vehicles, industrial machinery)
• Space-constrained designs that can’t accommodate SD card slots
• Applications needing consistent storage performance

Why Choose CM4 Lite (No eMMC)

The Lite variants trade integrated storage for flexibility and cost savings. But there’s a catch that trips up many first-time CM4 users.

Critical design requirement: CM4 Lite modules require a carrier board with a microSD card slot. The SDIO interface pins are only routed to the connector on Lite modules—on eMMC variants, these pins connect to the onboard flash instead. You cannot add microSD capability to an eMMC module later.

Cost advantages:

A CM4 Lite with 8GB RAM (CM4008000 or CM4108000) saves $15-20 compared to the equivalent 32GB eMMC variant. At production volumes, this adds up quickly.

Flexibility benefits:

With Lite modules, you can swap storage media without replacing the compute module. Field technicians can image cards at their desk and hot-swap them on site. During development, you can try different OS configurations without reflashing through USB boot mode.

When Lite makes sense:

• Development and prototyping phases
• Cost-sensitive volume production
• Applications requiring user-accessible storage
• Scenarios where field storage replacement is valuable
• Carrier boards with M.2 NVMe (boot from faster storage anyway)

Storage Decision Matrix

Factor	eMMC Preferred	Lite Preferred
Reliability priority	✓
Development flexibility		✓
Cost sensitivity		✓
No SD slot on carrier	✓
Using NVMe boot		✓
Vibration environment	✓
Field serviceability		✓

WiFi vs No WiFi: The Connectivity Decision

The wireless option adds only $5 to any CM4 configuration but carries implications beyond the obvious connectivity feature.

Why Choose CM4 with WiFi

Wireless CM4 variants include a fully certified dual-band radio module supporting 802.11 b/g/n/ac WiFi and Bluetooth 5.0 with BLE. The certification is the key value here.

Compliance simplification:

Raspberry Pi has completed modular wireless compliance certification for the CM4. When you design a product using the wireless CM4, you can leverage this certification rather than performing full RF testing on your end product. This saves weeks of compliance lab time and potentially thousands in testing fees.

Antenna options:

Wireless CM4 modules include both an onboard PCB trace antenna and a U.FL connector for external antennas. Software configuration switches between them. The external antenna kit (sold separately) is essential if your enclosure is metallic or otherwise RF-blocking.

When WiFi makes sense:

• Products requiring wireless connectivity
• Bluetooth peripheral support needed
• Want to leverage existing RF certification
• Remote configuration or monitoring requirements
• IoT gateway applications

Why Choose CM4 Without WiFi

The non-wireless CM4 variants aren’t just $5 cheaper—they serve specific engineering purposes.

Reduced EMI concerns:

In some industrial environments or RF-sensitive applications, having a transmitting radio onboard creates compliance headaches or interference issues. Medical devices, test equipment, and certain manufacturing environments often mandate no unintentional radiators.

Simplified compliance:

While the wireless certification helps when you want WiFi, it can complicate matters if you don’t. Some regulatory environments treat devices with any wireless capability differently, regardless of whether it’s enabled. Starting without wireless avoids these conversations entirely.

Lower power consumption:

The wireless subsystem draws power even when idle. For battery-powered or energy-harvesting applications, eliminating unused wireless saves precious milliamps.

When no WiFi makes sense:

• Ethernet-only connectivity sufficient
• RF-sensitive environments
• Strict EMC requirements
• Battery-powered applications
• Cost optimization at scale

Common CM4 Variant Combinations Explained

Let me decode the most popular CM4 variants you’ll encounter in the field.

CM4108032: The Flagship

The CM4108032 represents the fully-loaded option: WiFi, 8GB RAM, and 32GB eMMC. At around $100, it’s the premium choice for demanding applications where you want maximum headroom. Typical uses include media players, edge AI systems, and development work where you’d rather not hit memory limits.

CM4008032: Professional Non-Wireless

The CM4008032 matches the CM4108032’s 8GB RAM and 32GB eMMC but omits wireless. This is my go-to for industrial applications where the device connects via Ethernet and I want to avoid any RF considerations. Saves $5 per unit while eliminating an unused subsystem.

CM4104000: Balanced Wireless Lite

For wireless projects using NVMe storage or where microSD flexibility matters, the CM4104000 provides 4GB RAM with WiFi at a reasonable price point. The 4GB RAM handles most embedded Linux workloads comfortably.

CM4001000: Budget Baseline

The CM4001000 is the entry-level variant at $30: 1GB RAM, no WiFi, no eMMC. Useful for dedicated appliances with modest memory requirements and cost constraints. Digital signage players, simple automation controllers, and status displays often work fine with this configuration.

Practical Selection Guidelines

After specifying CM4 variants for numerous projects, here’s my decision framework.

Start with RAM

RAM cannot be upgraded later, and Linux systems benefit significantly from memory headroom. My recommendations:

• 1GB: Only for single-purpose appliances with controlled workloads
• 2GB: Adequate for lightweight services, basic GUIs
• 4GB: Sweet spot for most embedded applications
• 8GB: Required for containers, heavy processing, development

Then Consider Storage

If your carrier board has M.2 NVMe and you plan to boot from SSD, choose Lite—you’re paying for eMMC you won’t use.

If you need the simplicity and reliability of onboard storage, pick the appropriate eMMC size:

• 8GB: Minimal OS installations
• 16GB: Standard Raspberry Pi OS with applications
• 32GB: Media storage, logging, containers

Finally, Wireless

Add WiFi ($5) if:

• You need WiFi or Bluetooth functionality
• You might need it later (retrofitting is impossible)
• The pre-certification value exceeds $5 in saved testing

Skip WiFi if:

• Ethernet-only design
• EMC/RF constraints exist
• Every dollar matters at volume

Useful Resources for CM4 Projects

Here are resources I reference regularly when working with CM4 variants:

Official Documentation

• Raspberry Pi CM4 Datasheet: Complete electrical specifications and mechanical drawings
• CM4 IO Board Design Files: Reference carrier board schematics in KiCad format
• CM4 Product Brief PDF: Quick reference for all variants and pricing

Community Resources

• Jeff Geerling’s CM4 Review: Thorough benchmarks comparing eMMC vs SD vs NVMe performance
• Raspberry Pi Forums Compute Module section: Active troubleshooting community
• Jeff Geerling’s PCIe Database: Compatibility testing for carrier boards and peripherals

Compliance Information

• pip.raspberrypi.com: Official compliance certificates for all regions
• CM4 EMC and regulatory documentation

Frequently Asked Questions About CM4 Variants

Can I use a CM4 Lite module in a carrier board designed for eMMC variants?

Yes, physically. Both variants use identical 100-pin connectors. However, you must ensure the carrier board has a microSD slot—the SDIO pins are only functional on Lite modules. Without a microSD slot, you’d need to boot from USB or network, which limits practicality.

What’s the real-world performance difference between eMMC and microSD?

In benchmarks, CM4 eMMC delivers roughly 2-3x better random I/O performance compared to good microSD cards. Sequential performance is similar. For boot time and application responsiveness, eMMC provides a noticeably snappier experience. NVMe via PCIe is faster than both by a significant margin.

Can I add WiFi to a non-wireless CM4 later?

No. The wireless radio is integrated into the module’s PCB. Non-wireless variants physically lack the radio hardware—it’s not just disabled. If you might need wireless, buy the wireless variant upfront. The $5 premium is cheap insurance.

Which CM4 variant should I use for a home NAS project?

For NAS applications, I typically recommend CM4008032 or CM4004032 (without WiFi). You’ll connect via Ethernet anyway, and the larger RAM helps with file caching. The eMMC provides reliable OS storage while your actual data lives on SATA or NVMe drives connected through the carrier board.

Are extended temperature range CM4 variants available?

Yes. Raspberry Pi offers industrial-grade CM4 variants rated for -40°C to +85°C operation. These carry an “ET” suffix in the part number and are available through authorized distributors. They’re priced higher and often require minimum order quantities.

Final Thoughts

The 32 CM4 variants might seem overwhelming, but most projects quickly narrow to two or three realistic options once you’ve established RAM requirements, storage strategy, and wireless needs.

For most embedded projects, the CM4104032 (4GB RAM, 32GB eMMC, WiFi) or its non-wireless equivalent CM4004032 hits the sweet spot of capability and cost. Development work benefits from 8GB variants like the CM4108032 or CM4008032 to avoid memory constraints during iteration.

Remember: you can always buy more storage through NVMe, but you can’t upgrade RAM or add wireless after the fact. When in doubt, spec up on the unchangeable features and optimize cost elsewhere in your BOM.