Calculator
Example data
Use these values to test the calculator quickly.
| Absorbed Dose | Time | Weighting Factor | Absorbed Rate | Equivalent Rate |
|---|---|---|---|---|
| 2.0 mGy | 0.5 h | 1 | 4.0 mGy/h | 4.0 mSv/h |
| 120 µGy | 10 min | 1 | 720 µGy/h | 720 µSv/h |
| 0.08 Gy | 40 min | 20 | 0.12 Gy/h | 2.4 Sv/h |
Formula used
Absorbed dose rate is the absorbed dose per unit time:
Ḋ = D / t
Equivalent dose rate applies a radiation weighting factor:
Ḣ = Ḋ × wR
- D is absorbed dose (Gy or rad).
- t is exposure time (s, min, h, day).
- wR is the radiation weighting factor (dimensionless).
- Unit conversions used: 1 rad = 0.01 Gy, 1 rem = 0.01 Sv.
How to use this calculator
- Choose Absorbed or Equivalent dose rate.
- Enter the total absorbed dose and select its unit.
- Enter the exposure time and select its unit.
- If using equivalent dose rate, enter a suitable weighting factor.
- Select your preferred output units, then press Calculate.
- Use Download CSV or Download PDF after results appear.
Dose rate guide
Dose rate links measured dose to time, enabling consistent comparisons between surveys, experiments, and workplace checks. Use this guide to interpret values, units, and weighting choices.
1) What dose rate represents
Dose rate expresses how quickly energy is deposited in matter during an exposure. When the dose accumulates steadily, dividing total dose by exposure time summarizes the intensity of the field and helps compare measurements taken over different durations.
2) Absorbed dose rate units
Absorbed dose rate is commonly reported in Gy/h or mGy/h, while older instruments may display rad/h. The calculator applies the fixed conversion 1 rad = 0.01 Gy, so 100 rad/h = 1 Gy/h. For small values, 1 mGy/h = 1000 µGy/h.
3) Equivalent dose rate concept
Equivalent dose rate adjusts absorbed dose rate using a radiation weighting factor to reflect biological effectiveness. The relationship is Ḣ = Ḋ × wR. If Ḋ = 0.12 Gy/h and wR = 20, then Ḣ = 2.4 Sv/h.
4) Typical weighting factor data
Commonly used values include photons and beta particles at wR = 1 and alpha particles near wR = 20. Neutron weighting depends strongly on energy and may be treated as a range in practice, often from a few up to several tens.
5) Time averaging and short exposures
For brief measurements, dose rate can change quickly with distance, shielding, and source movement. If 120 µGy is received in 10 minutes, the average absorbed dose rate is 720 µGy/h. Longer integration times usually reduce random variation in survey readings.
6) Distance and shielding sensitivity
Small geometry changes can strongly affect dose rate. For point-like sources, intensity often decreases rapidly with distance, while shielding can reduce dose rate by attenuation. When reporting results, record distance, shielding thickness, and measurement height to support repeatable comparisons.
7) Instrument and calibration considerations
Survey meters and dosimeters may respond differently to energy spectrum and radiation type. Use calibration factors supplied for the detector and confirm the instrument range is appropriate; a saturated detector can under-report. If uncertainty is known, include it alongside the computed rate.
8) Practical reporting workflow
Use absorbed dose rate for physical comparisons and equivalent dose rate for protection-related summaries. Save the outputs in CSV for logs, then generate a PDF for audits. Include the input dose, time, units, and any weighting factor so the calculation is transparent.
FAQs
1) What inputs do I need for dose rate?
You need the total absorbed dose over a known exposure time. Pick matching units, then choose an output unit. Add a weighting factor only when you want equivalent dose rate.
2) Why is my equivalent dose rate blank?
Equivalent results appear only when you select the equivalent calculation type. The calculator then uses your weighting factor to convert absorbed dose rate to an equivalent dose rate value.
3) How do I choose the weighting factor?
Use the factor recommended for your radiation type and measurement context. Photons and beta particles commonly use 1, alpha particles commonly use 20, and neutron values depend on energy.
4) Can I enter rad or rem?
Yes. For absorbed dose, you can use rad and mrad, and the calculator converts them using 1 rad = 0.01 Gy. For equivalent dose rate outputs, rem and mrem are supported using 1 rem = 0.01 Sv.
5) What does “Gy/s” mean?
Gy/s is absorbed dose rate in grays per second. It is useful for very short exposures or pulsed sources. You can switch to Gy/h, mGy/h, or µGy/h for everyday monitoring reports.
6) How accurate are the results?
The math and unit conversions are deterministic, but accuracy depends on your dose measurement, time measurement, and detector calibration. If your meter provides an uncertainty, report it with the computed dose rate.
7) What should I include in a report?
Include the absorbed dose, exposure time, chosen units, any weighting factor, and the calculated absorbed and equivalent dose rates. Also note distance, shielding, and instrument details so others can reproduce the conditions.