SpiderWire Ultracast Braid
Diameter chart, reel capacity & backing guide
Ultracast is an eight-fiber PE braid. This guide is limited to the labeled 8 lb Inshore Camo package, not the full Ultracast range. Its 164-yard spool gives you a defined amount of working braid to plan around; a large capacity estimate does not mean you need to fill the entire reel with it.
- Construction
- 8-fiber PE braid
- Listed strengths
- 8 lb
- Line type
- Braid main line
A thin working line, with a specific label
The 8 lb Ultracast option covered here belongs on appropriately matched light tackle, with spinning gear a useful starting point. Its very small listed diameter can leave plenty of spare capacity even on a compact reel. Plan a working section with reserve for fish runs and trimming, then add backing as needed and finish at the reel maker's recommended fill level.
How much Ultracast will fit?
Calculated estimates, not measured fills. Stop at the reel manufacturer's fill level even if some line remains.
SpiderWire Ultracast Braid diameter chart
One verified package only: 8 lb Inshore Camo, labeled 164 yd / 150 m. Other Ultracast strengths are intentionally absent because their physical diameters and matching packages were not verified from the current manufacturer's evidence.
| Strength | Inches | mm | Spools (m / yd) |
|---|---|---|---|
| 0.0035 | 0.090 | 150 m (about 164 yd) |
Choosing your Ultracast strength
Match the 8 lb test rating to the rod, lure and likely loads first. Do not select it solely because the small published diameter produces a large capacity estimate.
The package also prints a maximum-break figure. That is a different label field, not a substitute for the 8 lb test rating and not an instruction to use a heavier drag setting.
Only this labeled variant is charted here. Use separately verified data for stronger Ultracast, another color formulation, or the older Ultimate Braid and Invisibraid products.
This is a specification-based guide. No casting-distance, abrasion or handling performance was independently tested.
Want a guided recommendation?
Continue in the Setup WizardSame pound test, different diameters
At your selected strength
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What changes with another line?
Nearby diameters in the line database
| Line | Strength | Inches | Difference |
|---|---|---|---|
| Loading line database... | |||
Backing, working line & leaders
Budget from the 164-yard package
Start with your required working length, leaving room for trimming and future losses. The examples use 125 or 150 yards from one package, not a promise that either length suits every fishery.
Fill the remaining volume underneath
Choose the exact reel before estimating mono backing. Follow its instructions for attaching braid; a smooth arbor may need an approved anti-slip attachment or a mono base. Backing length is a volume calculation, not a matching pound-test rule.
Choosing mono backingTreat the leader separately
Choose any lure-end leader for the presentation and contact hazards. It is not the backing beneath the braid, and its test rating need not copy the braid label. A long topshot needs a separate allowance for spool space.
Choosing a braid leaderCheck the final fill
Wind with controlled, even tension and stop at the reel manufacturer's specified clearance. Correct the backing amount if the actual fill differs from the estimate; do not force all the planned line onto an overfull spool.
How Much Fits on These Reels?
Estimated full-spool capacity for the Ultracast strength selected above, with no backing. These are calculated examples, not physical tests or recommendations for every pairing.
Loading capacity estimates...
Ultracast questions, answered
Why does this Ultracast chart show only 8 lb?
The currently displayed Inshore Camo package provides a readable test rating, both diameters and a matching length. Other strengths appear in the manufacturer's selector, but that alone does not verify their physical diameters or package combinations.
Is the 22 lb maximum-break marking another strength?
No. On the inspected package, 8 lb is the test label and 22 lb is a separate maximum-break claim. This chart uses the test label and does not create a 22 lb variant.
Does one package fill my reel?
That depends on the exact reel and the actual packing. Compare its estimated capacity with your required working length; use backing when a suitable working section is shorter than a full fill.
Can I use this diameter for Invisibraid or Ultimate Braid?
No. The evidence here identifies the Inshore Camo Ultracast x8 package. Similar names, old catalog groupings and matching pound-test labels do not establish identical physical diameters.
Why can the calculated capacity look unusually large?
The package lists a very small diameter. Capacity estimates depend strongly on that input, while actual braid packing also depends on winding tension and spool shape. Treat the result as a planning estimate and verify the final fill.
Specifications & sources
Checked September 13, 2026. The current US Ultracast page links the Inshore Camo package image used for this single row and lists the matching test strength and package length. The image filename dates the artwork to 2019. No claim of current stock, revised packaging or full-range verification is made.
Calculations use the catalog's listed inch diameters. Published inch and millimeter values may differ slightly because of rounding.
- Official Ultracast product page Current US page, construction, offered label options and the link to the inspected image. Not a full diameter table.
- Official labeled Inshore Camo package Visually checked numeric evidence for the sole charted variant; distinguishes test strength from maximum break.