Wide Mouth describes a Nalgene bottle family, not one cap diameter for every capacity. A replacement order that drops the bottle’s size can select the wrong part even when the brand and mouth description look correct.
The US 16oz Wide Mouth Cap record lists a 53mm cap diameter. The separate Wide Mouth Cap record for 32oz and 48oz bottles lists 63mm. Keep those product records distinct rather than assume a common Wide Mouth thread.
| Replacement record | Listed cap diameter |
|---|---|
| 16oz Wide Mouth Cap | 53mm. |
| Wide Mouth Cap for 32oz / 48oz | 63mm. |
Retain the bottle identity
Find the capacity and mouth type on the actual bottle or its original record. Photograph the neck and old cap alongside that information. A seller’s short title such as Nalgene lid may omit the one distinction that matters for this purchase.
If the bottle is old, unusually shaped or labelled differently, compare the manufacturer’s stated fit list instead of extrapolating from this two-row table. Listed cap diameter is a part-identification field, not an instruction to cut or adapt a thread that does not fit.
Check the offered part as well as the name
For a used bottle with a lost cap, record which replacement is being offered and whether it is the complete assembly pictured. Colour matching is secondary to matching the actual bottle. Do not force a cap that binds or infer sealing performance from a photograph of it resting on the neck.
Our ordering note would contain four entries: bottle capacity, mouth type, manufacturer replacement record and the offered part. This is also useful when purchasing spares for a household with different bottle sizes: keep each spare labelled rather than treating all wide-mouth caps as a communal pool.
Nalgene US cap records read 25 October 2026. No thread-fit, leak, pressure or durability test. Other cap types and bottles require their own compatibility check. Related: buying guides.
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