Calculator
White theme · Responsive gridChoose a calculation method, enter values with units, and press Calculate. Distance-time mode uses experimental latency, while diameter mode gives quick estimates.
Formula used
Distance-time method: Conduction velocity is computed from the traveled path length and effective latency:
v = d / (t - t_offset)
If you enable temperature scaling, the calculator applies a Q10 correction:
v_corr = v x Q10^((T - Tref)/10)
When distance and time uncertainties are provided, the calculator estimates relative uncertainty by propagation: Dv/v ~ sqrt[(Dd/d)^2 + (Dt/t)^2].
Diameter estimate method: A simple rule-of-thumb relates velocity to axon diameter (empirical scaling). For myelinated fibers the Hursh-style scaling is used:
v ~ k x d(um) (unmyelinated: v ~ 0.5 x d(um))
How to use this calculator
- Pick a method: distance and latency for experiments, or diameter estimate for planning.
- Enter values and select correct units. Use the offset to subtract fixed delays.
- Optionally add uncertainties to estimate a 1sigma velocity uncertainty.
- Enable temperature correction when comparing measurements at different temperatures.
- Press Calculate. Use the download buttons to export CSV or PDF.
Example data table
Sample values| Distance (cm) | Latency (ms) | Offset (ms) | Effective time (ms) | Velocity (m/s) |
|---|---|---|---|---|
| 10.0 | 2.0 | 0.0 | 2.0 | 50.0 |
| 12.5 | 2.8 | 0.2 | 2.6 | 48.08 |
| 8.0 | 1.6 | 0.1 | 1.5 | 53.33 |
These examples show how subtracting a delay offset increases the effective velocity by reducing the effective time. Your results will update above the form after calculation.
Axon conduction velocity guide
1) What conduction velocity represents
Conduction velocity is the speed at which an action potential propagates along an axon. In experiments it is commonly derived from the travel distance between stimulation and recording sites divided by the measured latency, after subtracting fixed delays. Faster velocities generally support rapid sensorimotor signaling and tighter timing precision.
2) Typical ranges you can compare against
Values depend on species, temperature, and fiber class. Unmyelinated C fibers are often about 0.5–2 m/s, while lightly myelinated A-delta fibers are frequently near 5–30 m/s. Large myelinated A-alpha motor fibers can reach roughly 80–120 m/s. These ranges help sanity-check results before exporting reports.
3) Distance–latency measurement workflow
For distance–time mode, measure the path length along the nerve (not straight-line spacing) and use a consistent latency definition (onset, peak, or threshold crossing). The offset field is useful when you want to remove a constant synaptic, stimulus artifact, or instrument delay so that the effective time reflects axonal propagation more directly.
4) Why temperature matters
Ion channel kinetics and membrane resistance change with temperature, so velocity usually increases as tissue warms. The Q10 correction in this calculator scales velocity by Q10^((T − Tref)/10). For example, with Q10 = 1.8, a 10°C increase predicts about an 80% increase in velocity, supporting fair comparisons across recordings.
5) Diameter-based estimates for planning
When direct latency data are unavailable, diameter mode provides a practical estimate. Myelinated fibers often follow an approximate linear scaling where velocity is proportional to diameter in micrometers. Unmyelinated fibers are slower and the estimate uses a smaller proportionality constant, giving order-of-magnitude guidance for protocol design.
6) Uncertainty and data quality
Small time errors strongly influence velocity because v = d/t. If you provide distance and latency uncertainties, the calculator propagates them into a relative uncertainty estimate. Improving trigger timing, sampling rate, and distance measurement can reduce uncertainty more effectively than increasing precision in only one variable.
7) Unit conversions and reporting
The form accepts common length and time units and converts internally to meters and seconds. Results are displayed in m/s and km/h for quick interpretation. Use the CSV export for spreadsheets and the PDF export for lab notes, sharing, or archiving consistent calculation settings.
8) Practical interpretation tips
Compare values within the same preparation and latency definition. Myelinated fibers can show conduction slowing under cooling, compression, or demyelination. Unmyelinated fibers may show broader latency dispersion. If results look implausible, re-check the effective distance, offset, and whether latency was measured to onset versus peak.
FAQs
1) Should I use onset or peak latency?
Use one definition consistently. Onset is often better for propagation timing, while peak can be more stable in noisy traces. Mixing definitions across trials can create misleading velocity differences.
2) What does the delay offset mean?
It is a constant time you subtract from latency, such as synaptic delay, stimulus artifact delay, or system latency. The calculator uses (latency − offset) as the effective propagation time.
3) Why is my calculated velocity extremely high?
Common causes are distance entered too large or too small, latency entered in the wrong unit, or an offset that nearly equals the latency. Check units, confirm path length, and ensure effective time remains positive.
4) How do I pick a Q10 value?
Q10 varies by tissue and preparation. Many physiological processes fall near 1.5–2.5. If you have calibration data, use that; otherwise start around 1.8 and report it alongside temperature and reference temperature.
5) Is diameter mode accurate enough for publication?
It is a planning estimate, not a substitute for measured distance and latency. Use it to set expectations or design protocols, then rely on experimental measurements for final reporting.
6) How is uncertainty calculated here?
When both distance and latency uncertainties are provided, the calculator uses standard propagation for v = d/t: relative uncertainty is sqrt((Dd/d)^2 + (Dt/t)^2). It then multiplies by the corrected velocity.
7) What is a reasonable velocity check for my data?
Compare against typical ranges: unmyelinated near 0.5–2 m/s, A-delta near 5–30 m/s, and large myelinated motor fibers roughly 80–120 m/s. Temperature and species can shift these values.