What this calculator does
Solenoid Magnetic Field works out magnetic field strength inside a long, tightly-wound solenoid carrying a steady current. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaB = μ₀nI, n = N/L, μ₀ = 4π×10⁻⁷ T·m/A
The inputs explained
| Field | What to enter |
|---|---|
| Number of turns | A number. Starts at 500. |
| Coil length (m) | A number, measured in m. Starts at 0.2. |
| Current (A) | A number, measured in A. Starts at 2. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with number of turns
Every other input is held at the calculator’s starting values while number of turns varies. Select any row to load that scenario into the calculator.
How the answer changes with number of turns
| Number of turns | Magnetic field inside solenoid (B) | Magnetic field inside solenoid (B) | Turns per unit length (n) |
|---|---|---|---|
| 250 | 3.142 mT | 3.1416e-3 T | 1,250.00 turns/m |
| 375 | 4.712 mT | 4.7124e-3 T | 1,875.00 turns/m |
| 500 | 6.283 mT | 6.2832e-3 T | 2,500.00 turns/m |
| 750 | 9.425 mT | 9.4248e-3 T | 3,750.00 turns/m |
| 1,000 | 12.566 mT | 1.2566e-2 T | 5,000.00 turns/m |
| 1,500 | 18.850 mT | 1.8850e-2 T | 7,500.00 turns/m |