Oscilloscope Bandwidth ↔ Rise Time

Convert bandwidth to rise time (and back) using standard scope response models. Great for checking whether a scope can faithfully capture fast edges.

How to Use

  1. Pick a model (common: Single-pole or Gaussian).
  2. Enter either Bandwidth or Rise Time (10–90%).
  3. Choose units (MHz, ns, etc.).
  4. Read the computed result and open Show Work for steps.
Most models use tr ≈ k / BW where k depends on the system response.
Quick Readout
Computed values update as you edit inputs (no URL changes).
Bandwidth
—
Rise Time
—
k Factor
—
Edge Check
—
tr ≈ k / BW
Where tr is 10–90% rise time and BW is bandwidth.
Tip: If your signal edge is faster than the scope’s rise time, the displayed edge will look slower than reality.
Inputs & Settings
Enter one value to compute the other. Choose a response model (k factor).
Common: 50 MHz, 100 MHz, 200 MHz, 500 MHz, 1 GHz+
If you know bandwidth, rise time is often in ns/ps for fast edges.
k depends on how the system responds to a step (model choice matters).
Used only when “Custom k factor” is selected.
Show Work (step-by-step)
—
Work is shown in base units (Hz and seconds) for clarity.

Reference

A common approximation for a scope/channel is: tr ≈ k / BW (BW in Hz, tr in seconds).

Model Typical k Notes
Single-pole 0.35 Very common “rule of thumb” for many scopes/channels.
Gaussian 0.339 Often quoted for “Gaussian response” front-ends.
Custom user Use when your vendor specifies a different relationship.
Note: This tool focuses on bandwidth ↔ 10–90% rise time conversions. If you need system rise-time combining (scope + probe + source), you’ll want an RSS combine tool (related tools section).

FAQ

Why does bandwidth limit rise time?

Limited bandwidth filters out high-frequency components of a fast edge, so the measured transition becomes slower.

Which k factor should I use?

If you don’t know, 0.35 (single-pole) is the common approximation. Use Gaussian if your scope documentation specifies it. Otherwise use Custom.

If my signal rise time is 1 ns, what scope bandwidth do I need?

Using k = 0.35: BW ≈ 0.35 / 1 ns ≈ 350 MHz (rough estimate). Many engineers target higher BW for margin.

Does this replace vendor specs?

No—this is a conversion tool using common models. Always prefer vendor specs when available.

Tool Info

Last updated:

Updates may include additional response models, edge-case handling, and UI improvements.