QSFP+ vs QSFP28 — 40G vs 100G Transceiver Comparison
QSFP+ supports 40 Gbps; QSFP28 supports 100 Gbps. Physically interchangeable form factor — same housing, same fiber connector — but require electrically-different switch ports.
Quick Verdict
QSFP28 (100G) is the modern standard for data center backbone since 2018. QSFP+ (40G) remains common in legacy deployments. Most QSFP28 switches accept QSFP+ modules at downgraded 40G speed.
Side-by-Side Spec Comparison
| Spec | QSFP+ (40G) | QSFP28 (100G) |
|---|---|---|
| Speed | 40 Gbps (4x 10G lanes) | 100 Gbps (4x 25G lanes) |
| Form Factor | QSFP+ (identical to QSFP28) | QSFP28 |
| Reach (SR multimode) | 100m (OM3) / 150m (OM4) | 70m (OM3) / 100m (OM4) |
| Reach (LR single-mode) | 10km | 10km |
| Switch Compatibility | Plugs into QSFP+ and QSFP28 ports | QSFP28 ports only (won't run in QSFP+ ports) |
| Breakout Options | 4x SFP+ 10G via breakout cable | 4x SFP28 25G via breakout cable |
| Refurbished Price | $30-80 (SR), $150-300 (LR) | $60-150 (SR), $300-700 (LR) |
Green-highlighted cells indicate the winner for that spec.
Frequently Asked Questions
Are QSFP+ and QSFP28 the same form factor?
Yes — physically identical, same housing, same MPO/MTP fiber connector. The difference is in the electrical signaling: QSFP+ runs 4x 10G NRZ lanes; QSFP28 runs 4x 25G NRZ lanes.
Can I plug a QSFP+ into a QSFP28 port?
Yes — modern QSFP28 switch ports accept QSFP+ modules at downgraded 40G speed. Reverse is NOT true: QSFP28 modules require QSFP28 electrical capability and won't run in older QSFP+ switches.
Should I deploy 40G or 100G now?
100G — new switch deployments should be QSFP28-based. 100G optics cost ~2× 40G but the bandwidth doubles + future-proofs you. For legacy 40G upgrades, you can typically run QSFP+ modules in QSFP28 switches as a gradual migration.
Our Recommendation
For new deployments, QSFP28 100G. For upgrades, deploy QSFP28 switches but use QSFP+ modules on existing fiber until you can switch to 100G modules.
Need help deciding?
Email sales@prodisknetwork.com with your specific requirements. Our team will match you to the right product based on your workload, budget, and existing infrastructure.