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Channel Count / Bandwidth Occupancy Calculator

Find out how many equally-spaced radio channels fit inside a frequency band and how much of the band is occupied. Enter the total bandwidth, the channel spacing and an optional guard band to get the channel count, and add a used-channel count for the occupancy percentage.

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How to use this calculator

Enter Values

Enter your values and press Calculate to see results.

Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.

How to use this calculator

  1. Enter the total available bandwidth of the band in kHz (e.g. 12.5 MHz = 12500 kHz).
  2. Enter the channel spacing in kHz and, if channels need separation, a guard band per channel.
  3. Optionally enter how many channels are in use to see the band occupancy as a percentage.

How it works

Each channel occupies a slot equal to the spacing plus its guard band. The number that fit is floor(total / (spacing + guard)) — rounded down because a partial slot cannot carry a channel. Occupancy, when a used count is given, is used × (spacing + guard) / total × 100, i.e. the fraction of the band those channels take up.

Worked example

Worked example. A 12.5 MHz (12500 kHz) band with 25 kHz spacing and no guard band fits floor(12500 / 25) = 500 channels. If 200 of them are in use, occupancy = 200 × 25 / 12500 × 100 = 40%.

Common mistakes

  • Mixing units — the total bandwidth and the spacing must both be in kHz (convert MHz by ×1000).
  • Forgetting the guard band, which reduces how many channels fit and raises the per-channel width.
  • Assuming every channel that fits is usable — regulators reserve edge guard bands and enforce a fixed raster, so the practical count can be lower.

Frequently asked questions

Why does the calculator round the channel count down?

A channel needs a full slot of spacing plus guard band. If the leftover bandwidth is smaller than one slot it cannot host another channel, so the count is floored and the remainder is shown as unused bandwidth.

What is a guard band and when should I add one?

A guard band is spare spectrum around each channel that stops adjacent channels interfering. Add it when the modulation's occupied bandwidth or filter roll-off means channels need separation beyond the raw spacing; leave it at 0 for a simple back-to-back channel plan.

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Tip: Enter any known values to calculate the remaining results.

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