Coriolis Effect Calculator — Deflection Force
Compute the Coriolis acceleration and force acting on any moving object at a given latitude. The Coriolis effect deflects moving air, water, and projectiles to the right in the Northern hemisphere and to the left in the Southern hemisphere.
m/s
°
kg
Direction of motion
a_c = 2 Ω v |sin φ| where Ω = 7.2921 × 10⁻⁵ rad/s
- 1
sin(latitude)
sin(45°) = 0.707107 - 2
Coriolis parameter f = 2Ω sin φ
2 × 7.2921e-5 × 0.707107 = 0.000103 s⁻¹ - 3
Acceleration a_c = |f| × v
0.000103 × 50 = 0.005156
How does this calculator work?
The Coriolis acceleration is a_c = 2Ωv|sin φ|, where Ω = 7.2921 × 10⁻⁵ rad/s, v is object speed, and φ is latitude. It deflects motion to the right in the Northern hemisphere, left in the Southern, and is zero at the equator. Multiply by mass to get the Coriolis force in newtons.
Formula
How this is calculated
The Coriolis effect is an apparent deflection force that acts on objects moving relative to a rotating reference frame — in everyday terms, relative to the rotating Earth. Any object in free motion (wind, ocean current, long-range projectile) appears to curve because the ground beneath it is rotating while the object moves in a straight line in space. The acceleration magnitude is a_c = 2Ωv|sin φ|, where Ω is Earth's angular velocity (7.2921 × 10⁻⁵ rad/s), v is the object's speed, and φ is the latitude.
The direction of the deflection depends on hemisphere: in the Northern hemisphere the force acts 90° to the right of the velocity vector; in the Southern hemisphere it acts 90° to the left. At the equator (φ = 0°) the Coriolis effect vanishes entirely because sin(0) = 0. The effect is strongest at the poles (|sin 90°| = 1). The Coriolis parameter f = 2Ω sin φ appears in meteorology and oceanography as the scaling constant in the equations of geostrophic flow.
In practice the Coriolis effect is significant only for large-scale motions over hours or hundreds of kilometres — synoptic weather systems, ocean gyres, and ballistic trajectories. For everyday objects like water draining from a sink, surface tension and the initial swirl dwarf the Coriolis force by orders of magnitude.
Frequently asked questions
No — the Coriolis force on a small toilet bowl is about 10 million times weaker than the forces from the shape of the bowl and the initial conditions. The direction water drains depends entirely on the toilet's geometry, not the hemisphere. Large weather systems (hundreds of km) rotate under Coriolis influence; a sink drain does not.
The formula a_c = 2Ωv|sin φ| contains sin φ. At the equator φ = 0°, so sin(0) = 0 and the acceleration is zero. The equatorial plane is perpendicular to Earth's rotation axis, so no component of Earth's spin deflects horizontal motion there.
Hurricanes rotate counter-clockwise in the Northern hemisphere and clockwise in the Southern hemisphere because the Coriolis force deflects air flowing inward (toward low pressure) to the right in the north and to the left in the south. Without Earth's rotation, converging air would simply pile straight in and not spin.
Also known as
TG we-Calculate Editorial Team. (2026). Coriolis Effect Calculator — Deflection Force [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/coriolis-effect-calculator
TG we-Calculate Editorial Team. "Coriolis Effect Calculator — Deflection Force." TG we-Calculate. 2026. https://we-calculate.com/calculator/coriolis-effect-calculator.
TG we-Calculate Editorial Team, "Coriolis Effect Calculator — Deflection Force," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/coriolis-effect-calculator
@misc{wecalculate_coriolis_effect_calculator, title = {Coriolis Effect Calculator — Deflection Force}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/coriolis-effect-calculator}}, year = {2026}, note = {TG we-Calculate} }
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