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Guide

Channel letter LED calculator

Estimate LED modules, total wattage and power supply from letter height, letter count and return depth; a 50 cm × 8 letter example is preset.

Dimensions

Dimension source

Height of the tallest capital letter.

Do not count spaces or punctuation.

Font weight

Stroke width of the letters; bold lettering needs more modules.

LED and installation

Inside depth of the letter or box. Module spacing grows with depth.

Voltage
Installation

Wide-angle (lens) modules can be spaced further apart.

Advanced settings

Added for failures and installation losses; 10% recommended.

Cable from the power supply to each feed line; cross-section and voltage drop are chosen from it.

Enter the dimensions to see the result.

What this page calculates

The tool estimates how many LED modules a channel letter sign needs, the total wattage, the recommended power supply, the number of feed lines and the cable cross-section from letter height, letter count, font weight and return depth. You can also upload the letters as an SVG drawing; then the real area and outline of each letter are used.

Method

  1. Module spacing = return depth × the model’s spacing ratio (1.5 for 160° lens modules), kept within 6–15 cm.
  2. Rows: if the stroke is wider than one row can light at that depth, modules are laid in two or more rows.
  3. Count = the larger of the stroke estimate (rows × centre line ÷ spacing) and the area estimate (area ÷ spacing²), plus 10% spares.
  4. Power: required PSU power = total power × 1.25; modules are split into feed lines by the chain limit (typically 20 modules for 12 V).

Example: 50 cm × 8 letters, 10 cm depth

Spacing 15 cm, one row. 56 modules (62 with spares), 84 W, required PSU power 105 W, so 1 × 120 W is recommended, with 3 feed lines (19 + 19 + 18).

The result is an estimate; test the layout on a sample letter, and have a qualified electrician make the connections.

Source: spacing guidance from the GE Current Tetra channel letter spacing guidelines (TET_SIGN377EU); module values from typical data sheets. Check against the data sheet of the stocked product.

Last updated: 18 October 2026 · Full tool page

How it works

From dimensions to a material list in three steps.

  1. Choose the calculation

    Channel letters, light box, or LED strip and neon. For letters, enter the size or upload your SVG drawing.

  2. Set the model and location

    Choose the return depth, module or strip model and indoor/outdoor; the result updates instantly.

  3. Add the list to the basket

    Add the module, power supply and cable list to the project basket and request one quote.

Frequently asked questions

Why does module spacing depend on return depth?

Light spreads until it reaches the face. The deeper the return, the larger the area each module lights, so modules can be spaced further apart. With wide-angle (160°) lens modules the spacing is about 1.5 times the depth; about 15 cm at 10 cm depth.

How many modules does a 50 cm letter need?

In a regular-weight typeface at 10 cm depth, about 7 modules with 1.5 W lens modules. For 8 letters the tool calculates 56 modules, 62 with 10% spares.

How many watts does a channel letter sign draw?

Module count × module wattage. 56 modules × 1.5 W = 84 W. Because no more than 80% of the power supply capacity is used, the required PSU power is 84 × 1.25 = 105 W and a 120 W power supply is chosen.

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