# Engineering and student calculator for Mac, Windows and Linux

Written on 25 October 2026 by Ratio.

Homework and lab sums with the units kept: volts and ohms give amps, grams of a compound give moles, and a matrix gives its inverse.

## Electronics

| 12 V / 4 ohm | 3 A |
| --- | --- |
| 12 V * 2 A | 24 W |
| 10k \|\| 4.7k | 3,197.2789 |
| 100 ohm \|\| 100 ohm \|\| 100 ohm | 33.33 Ω |
| brown black red gold | 1 kΩ ±5% |
| 4.7k in colors | yellow violet red |
| 4700 ohm in eng | 4.7 kΩ |

## Chemistry

Formulas with brackets and hydrates work, using the IUPAC standard atomic weights.

| molar mass H2SO4 | 98.072 g/mol |
| --- | --- |
| molar mass Ca(OH)2 | 74.092 g/mol |
| 10 g H2O in mol | 0.5551 mol |
| 2 mol NaCl in g | 116.88 g |

## Algebra and matrices

| solve x^2 - 5x + 6 = 0 | x = 2 or x = 3 |
| --- | --- |
| det([[1,2],[3,4]]) | -2 |
| inverse([[1,2],[3,4]]) | [[-2, 1], [1.5, -0.5]] |
| [[1,2],[3,4]] * [[5],[6]] | [[17], [39]] |
| dot([1,2,3],[4,5,6]) | 32 |
| cross([1,0,0],[0,1,0]) | [0, 0, 1] |

## Grades and rounding

| grades 9 x3, 7 x2 | 8.2 |
| --- | --- |
| 1234.5 to 3 sig figs | 1,230 |
| 12345 in eng | 12.345 × 10³ |
| integral(x^2, 0, 3) | 9 |

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## Questions

**Does it know the resistor colour code?** Yes, both ways: “brown black red gold” gives 1 kΩ ±5%, and “4.7k in colors” gives yellow violet red. Four- and five-band codes work.

**How do I add resistors in parallel?** Write || between them: “10k || 4.7k”. Units are kept, so “10 kohm || 4.7 kohm” answers in kΩ.

**Can it do matrices?** Determinant, inverse, transpose, trace and products of matrices written as [[1, 2], [3, 4]], plus dot and cross products of vectors.

Source: https://useratio.app/engineering-calculator