Calculation methods and verification
The formulas, units, rounding rules, verification examples and error-reporting process used by FieldCalc.
Scope
Free tools for preliminary machinery calculations. Examples are constructed assumptions explaining relationships, not claimed repair records or measurements from specific equipment. These tools do not approve equipment selections or safety.
| Tool | Formula | Basis |
|---|---|---|
| RPM | n out = n in / i | i = n in / n out |
| Pulley | n2 = n1 × D1 / D2 | D1, D2: same unit; no slip |
| Torque | T = 60000 × P / (2π × n) | P: shaft kW; n: RPM; T: N·m |
| Power | 1 hp ≈ 0.745699872 kW; 1 PS = 0.73549875 kW | mechanical hp / metric PS |
Rounding and units
The calculator uses 60000 ÷ (2π) rather than the rounded 9550 constant for torque. Final digits can differ from the rounded examples in the guide. Results display up to four decimal places. Comparison tables use SI units independently of the main calculator US-unit setting.
| Inputs | Expected result |
|---|---|
| 1400 RPM / 10 | 140 RPM |
| 1440 RPM × 150 mm / 300 mm | 720 RPM |
| 2.2 kW, 1450 RPM | 14.4886 N·m |
| 1 kW → mechanical hp | 1.3410 hp |
Input limits
The main calculators require positive inputs. Zero-power and zero-RPM operating states are outside their current scope. Empty, negative or out-of-range values are not valid results. Slip, efficiency, acceleration torque, thermal limits and allowable loads require separate review.
Report an issue
Send the page URL, language and unit settings, inputs, observed result and expected result by email. Private customer data or confidential equipment documents are not needed. Confirmed errors are corrected in the relevant tools and guides.