The Scientific Calculator — SI Money Tracker

Why a budgeting app ships a real calculator

Most finance apps bolt on a basic four-function calculator as an afterthought. This one is different: a real, general-purpose scientific calculator — kinematics and Newton's laws, the ideal gas law, tensors and rotation matrices, CIE and OKLCH color science, even a frequency-to-color mapping for audio.

Every tier, every language

Not a premium add-on. It ships in every tier at no extra charge, starting with your free seven days, because a genuinely useful tool shouldn't be a paywall bargaining chip.

A sample from the calculator registry

Real function signatures, pulled directly from the shipped engine — not a mockup.

Physicsgravitational_force(mass1, mass2, separation_m) -> float
Physicsdrag_force(velocity_ms, drag_coefficient, cross_section_area_m2) -> float
Physicsideal_gas_pressure(n_moles, temperature_kelvin, volume_m3) -> float
Physicspendulum_period_small_angle(length_m, gravity) -> float
Linear algebra / tensorsrotation_matrix_z(theta_radians) -> ndarray
Linear algebra / tensorsinertia_tensor_cuboid(mass, a, b, c) -> ndarray
Linear algebra / tensorslevi_civita_3d(i, j, k) -> int
Color sciencecorrelated_color_temperature_mccamy(x, y) -> float
Color sciencegamut_coverage_percent(gamut_triangle, reference_triangle) -> float
Tone & colorsrgb_to_oklch(r_srgb, g_srgb, b_srgb) -> (L, C, H)
Tone & colorfrequency_to_hue_degrees(frequency_hz, reference_hz) -> float
Statistics & numerical methodssimpsons_rule(f, a, b, n) -> float
Statistics & numerical methodsmatrix_determinant(matrix) -> float
Statistics & numerical methodsnormal_pdf(x, mu, sigma) -> float