Calculate expected belt cut weight and percentage error
Enter a flow rate, belt speed and cut length to see the expected net material weight straight away. Add your measured cut weights when you want to compare the results. Free to use, with no sign-up.
Diagnostic comparison only. This calculator does not establish totalised-tonnage accuracy, certify a belt weigher or prescribe a span adjustment. Follow your site’s approved isolation and sampling procedures before accessing a conveyor.
How to use the belt cut calculator
Choose flow rate and belt speed, or enter the integrator’s loading directly in kg/m. Use representative readings from the same steady operating period before stopping the belt. Enter the measured cut length to see the expected net material weight, without needing any sample weights. For example, 50 t/h at 2.5 m/s gives approximately 5.556 kg/m: a 1 m cut would contain 5.556 kg, or a 2 m cut 11.111 kg, if the material loading matches that reading. These are net material weights, excluding the container. To compare measured results, enter the gross and tare weights for at least two cuts. Three cuts provide another sample for comparison; they are not a universal test requirement.
If your reference scale already shows net material weight after taring, enter that weight as gross and use 0 for tare here. For several buckets from the same cut, add their gross weights together and their tare weights together before entering the row. Do not count each bucket as a separate belt cut. Use one common cut length throughout a calculation.
Belt loading and percentage-error formulas
- Indicated loading (kg/m) = flow rate (t/h) ÷ [3.6 × belt speed (m/s)].
- Expected net weight per cut (kg) = indicated loading (kg/m) × cut length (m).
- Net material mass (kg) = gross weight − tare weight.
- Sampled loading (kg/m) = net material mass ÷ cut length (m).
- Average sampled loading = sum of the cut loadings ÷ number of cuts.
- Loading error (%) = (indicated loading − average sampled loading) ÷ average sampled loading × 100.
- Sample variation, CV (%) = sample standard deviation of the cut loadings ÷ their mean × 100. The sample standard deviation uses n − 1.
Worked example
At 349.5 t/h and 2.5 m/s, the calculated integrator loading is 38.833 kg/m. Three 1 m cuts with net masses of 38.700, 39.400 and 38.300 kg give an average sampled loading of 38.800 kg/m. The loading error is +0.086%, with sample CV of 1.43%. Select “Load example” to try these figures. Calculations use unrounded values; displayed figures are rounded.
What does the result mean?
A positive error means the integrator loading is above the sampled average. A negative error means it is below. The optional comparison limit checks the size of this difference against a limit you enter. It does not decide whether the complete weightometer passes calibration, meets an accuracy class or is suitable for trade.
CV describes how much the sampled kg/m values differ from one another. Material distribution, sampling technique and reference weighing can all contribute. A small CV does not prove that the samples are representative or that the reference measurement is correct. There are no automatic “good” or “poor” CV thresholds in this calculator.
Plan the sampling before using the result
This tool calculates from readings you provide. Work on or near a conveyor, or inside an electrical enclosure, needs isolation under your site’s procedures and trained, authorised people. If that’s not you, stop and call us on 1300 101 666. Use a suitable calibrated reference scale with adequate capacity, resolution and measurement uncertainty for the comparison.
The sampled material must reasonably represent the operating conditions behind the integrator reading. Changing feed, belt run-down, material movement, lost fines, an incorrect cut length or double-counting tare can affect the comparison. Do not access or sample a moving conveyor. Follow the equipment and site procedures rather than treating a generic online guide as a work instruction.
Frequently asked questions
Does the belt cut have to be exactly one metre?
No. The calculator divides net material mass by the length entered in metres. All cuts in one calculation must use that same measured length. Net kilograms equal kg/m only when the cut length is 1 m.
Does a static belt cut prove totalised-tonnage accuracy?
No. This compares sampled belt loading with indicated kg/m at the selected conditions. It does not independently establish the accuracy of speed measurement, accumulated tonnes or the full operating range. Read our belt cut testing guide and calibration methods guide for the wider context.
Can I use this for Australian trade verification?
This calculator is a diagnostic aid, not a trade-verification test or certificate. Formal verification follows the applicable approved instrument requirements and National Instrument Test Procedures. See NMI guidance for weighing instruments used for trade.
Should I change the span factor if the error is large?
Investigate the readings, sampling and equipment condition first. The appropriate correction and parameter convention depend on the integrator and calibration method. This calculator does not recommend a replacement span value. Contact Accurate Industries for weightometer calibration and fault finding if the result needs investigation.
Can I save the calculation?
Use “Print / save as PDF” to print your entries and results or choose your browser’s PDF destination. The calculator does not save or submit readings. Reloading or clearing the page removes the entries.
Need a belt weigher manual or help with the result?
Talk to us about manuals for your equipment: email your make, model and a photo of the label and we’ll help you find the right document. For a service enquiry, include your readings, cut length, weighing method and the issue you are investigating. You can also contact our team or explore our belt weighers and conveyor belt scales.