Ice Fishing Sonar Cone Coverage Calculator
Calculate fish-finder sonar cone diameter at any depth.
Enter cone angle and water depth to see coverage diameter and area at the bottom for ice fishing.
Sonar Cone Coverage
A fish-finder transducer emits a cone-shaped beam of sound. A wider cone scans more water and tells you less about any particular part of it.
The cone diameter formula: Diameter = 2 × Depth × tan(Cone Angle / 2)
Common ice-fishing transducer cone angles:
| Angle | Use Case |
|---|---|
| 8° | Tightest cone, best resolution, and it will miss a fish sitting off to the side |
| 12° | Standard medium-cone, Vexilar FL series, MarCum |
| 16° | Wider, covers more, less detail |
| 20° | Wide cone, search/scout, less ID detail |
| 24° | Very wide, for shallow water where a narrow cone sees almost nothing |
Practical examples (12° cone: most common):
| Depth | Cone Diameter | Coverage Area |
|---|---|---|
| 10 ft | 2.1 ft | ~3.5 sq ft |
| 20 ft | 4.2 ft | ~14 sq ft |
| 30 ft | 6.3 ft | ~31 sq ft |
| 40 ft | 8.4 ft | ~55 sq ft |
| 60 ft | 12.6 ft | ~125 sq ft |
| 100 ft | 21.0 ft | ~347 sq ft |
For ice fishing specifically:
- The cone diameter figure everyone quotes is the width at the BOTTOM, which is the widest the cone ever gets. A fish suspended halfway up is inside a cone half that wide, so it has to be much closer to your hole before it appears at all.
- A wider cone shows more “blips” but is harder to use for placing your jig precisely on a fish
- For deep lake trout (60-100 ft), wide cones miss less; for shallow panfish (10-20 ft), tighter cones give better jig-presentation feedback
Side-by-side jigging: In 30 ft of water a 12° cone is 6.3 ft across at the bottom, so two holes 6 ft apart are already touching: you will each mark the other person’s jig. Nine or ten feet apart clears it with room to spare. The rule that works at any depth is one and a half times the cone diameter, which the calculator works out for you.
Best ice-fishing electronics tips:
- 8-12° cone for finesse panfishing
- 16-20° for searching new structure
- Always confirm cone angle in your unit’s spec sheet: manufacturers vary
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This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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