G.657.A1 and G.657.A2 are candidates to review for access-network fiber selection, but the useful comparison is the complete offered specification. The source products on this site publish different bend-test conditions and coating values. Compare radius, turns and wavelength together with the allowed loss; the loss number alone does not demonstrate the difference. Check attenuation, mode field diameter, coating tolerances and the requirements of your cable construction. If tighter routing is part of the project, identify the relevant optical test requirement and separately confirm the finished cable installation limits. Do not assume that an A2 designation or a reduced coating automatically qualifies the product for your process. Request written confirmation of the supplier grade, coating and applicable documents.
Reference specification comparison
Values below are the same supplier reference data shown on the product pages. Different test conditions occupy separate rows; “Not listed” means the cited product table does not provide that entry.
| Parameter / condition | G.657.A1 | G.657.A2 |
|---|---|---|
| Attenuation at 1310 nm | ≤ 0.350 dB/km | ≤ 0.350 dB/km |
| Attenuation at 1550 nm | ≤ 0.210 dB/km | ≤ 0.210 dB/km |
| Cladding diameter | 125 ± 0.7 μm | 125 ± 0.7 μm |
| Coating diameter | 245 ± 10 μm / 200 ± 10 μm | Not listed in reference |
| Cable cut-off wavelength | ≤ 1260 nm | Not listed in reference |
| Macrobend: 15 mm radius, 10 turns, 1550 nm | ≤ 0.25 dB | Not listed in reference |
| Coating diameter (table value) | Not listed in reference | 242 ± 7 μm / 200 ± 10 μm |
| Mode field diameter at 1310 nm | Not listed in reference | 8.6 ± 0.4 μm |
| Macrobend: 7.5 mm radius, 1 turn, 1550 nm | Not listed in reference | ≤ 0.40 dB |
Compare the published bend conditions
The supplied A1 reference includes a 15 mm radius, ten-turn test at 1550 nm. The A2 reference includes 10 mm and 7.5 mm radius tests at 1550 nm with one turn. The product table retains these conditions so that a reader does not mistakenly compare the dB figures as if the test arrangements were identical.
To evaluate a shared project requirement, ask both offers to address the required condition. If a datasheet does not state it, request clarification or applicable evidence. Do not extrapolate a new loss limit from the available values.
Confirm the exact coating specification
The standalone A1 datasheet used here lists 245 μm and 200 μm coating options with their tolerances. For A2, this site follows the coating values in the supplied manufacturer specification table. These sources should not be silently rewritten into a common nominal coating value for a simpler comparison.
Tell the supplier which coating is required by your cable design. If an alternative is proposed, have the production or engineering team review the exact diameter, tolerance and relevant process requirements.
When to shortlist each product
Start an A1 or A2 review with the access application, physical route and loss budget. If the design calls for more demanding bend conditions, compare the applicable A2 reference tests and confirm that the offered product meets the specified condition. If the existing process is qualified around an A1 specification, identify what must be rechecked before a substitution.
For either option, obtain the actual supplier specification and agree on the batch documentation. A category label, a website comparison or a general compatibility statement does not replace that project-specific confirmation.
What to confirm
- The same wavelength for compared optical values
- Radius and turn count with each bend-loss value
- Exact nominal coating and tolerance
- Required geometry and joining criteria
- Finished-cable installation requirements
Frequently asked questions
Which is more bend resistant, A1 or A2?
The A2 reference includes tighter-radius test conditions. Use the full radius, turns, wavelength and limit when discussing bend performance; different test conditions are not a direct numerical comparison.
Can I use either grade for FTTH?
They can be considered during access selection, but the offered specification must satisfy the actual optical, cable-design and installation requirements.
Can 242 μm and 245 μm coating values be treated as identical?
Do not assume equivalence from the nominal values. Confirm the specific coating option and tolerance against the intended manufacturing process.
Sources & reference context
This guide is published by OpticFiberHub and summarizes the supplier literature identified below with editorial purchasing guidance. Product values describe the source grade, not a measured result or a conformity guarantee for a new order.
- G.657.A1 reference specifications — BendCom G.657.A1 Bending Insensitive Single-mode Optical Fiber datasheet, pages 1–2.
- G.657.A2 reference specifications — Jiangsu Nanfang Optical Fiber Product Manual, pages 7–8.
Quality & technical resources explains source selection, translated documents and the limits of historical batch records. Request the current specification and applicable records for the actual offered material.
Further terminology reference: The Fiber Optic Association: optical fiber fundamentals.
Single-mode standard references: ITU-T G.652 and ITU-T G.657. Supplier reference values above must not be mistaken for a reproduction of every requirement in those Recommendations.
