Free Physics Formula Lookup & Calculator

Search 80+ physics formulas by topic with variable definitions and solve-for-any-variable calculator. Free, fast, and works entirely in your browser with no sign-up required.

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Physics Formula Lookup & Calculator

Search 80+ physics formulas organized by topic — mechanics, waves, thermodynamics, electricity, and optics. Includes a solve-for-any-variable calculator.

35 formulas

Velocity

Mechanics

v = d / t

Velocity equals displacement divided by time.

v = Velocity (m/s)

d = Displacement (m)

t = Time (s)

Acceleration

Mechanics

a = Δv / t

Acceleration is the change in velocity over time.

a = Acceleration (m/s²)

Δv = Change in velocity (m/s)

t = Time (s)

Kinematic Equation (v = u + at)

Mechanics

v = u + a·t

Final velocity from initial velocity, acceleration, and time.

v = Final velocity (m/s)

u = Initial velocity (m/s)

a = Acceleration (m/s²)

t = Time (s)

Kinematic Equation (s = ut + ½at²)

Mechanics

s = u·t + ½·a·t²

Displacement from initial velocity, acceleration, and time.

s = Displacement (m)

u = Initial velocity (m/s)

a = Acceleration (m/s²)

t = Time (s)

Newton's Second Law

Mechanics

F = m·a

Force equals mass times acceleration.

F = Force (N)

m = Mass (kg)

a = Acceleration (m/s²)

Weight

Mechanics

W = m·g

Weight equals mass times gravitational acceleration (g ≈ 9.81 m/s²).

W = Weight (N)

m = Mass (kg)

g = Gravitational acceleration (m/s²)

Kinetic Energy

Mechanics

KE = ½·m·v²

Kinetic energy of a moving object.

KE = Kinetic energy (J)

m = Mass (kg)

v = Velocity (m/s)

Gravitational Potential Energy

Mechanics

PE = m·g·h

Energy stored due to an object's height above a reference point.

PE = Potential energy (J)

m = Mass (kg)

g = Gravity (m/s²)

h = Height (m)

Work

Mechanics

W = F·d·cos(θ)

Work done by a force over a displacement at angle θ.

W = Work (J)

F = Force (N)

d = Displacement (m)

θ = Angle (°)

Power

Mechanics

P = W / t

Power is work done per unit time.

P = Power (W)

W = Work (J)

t = Time (s)

Momentum

Mechanics

p = m·v

Linear momentum equals mass times velocity.

p = Momentum (kg·m/s)

m = Mass (kg)

v = Velocity (m/s)

Centripetal Acceleration

Mechanics

a_c = v² / r

Centripetal acceleration for circular motion.

a_c = Centripetal acceleration (m/s²)

v = Speed (m/s)

r = Radius (m)

Newton's Law of Gravitation

Mechanics

F = G·m₁·m₂ / r²

Gravitational force between two masses. G = 6.674 × 10⁻¹¹ N·m²/kg².

F = Force (N)

G = Gravitational constant (N·m²/kg²)

m₁ = Mass 1 (kg)

m₂ = Mass 2 (kg)

r = Distance (m)

Friction Force

Mechanics

f = μ·N

Friction force equals coefficient of friction times normal force.

f = Friction force (N)

μ = Coefficient of friction (dimensionless)

N = Normal force (N)

Wave Speed

Waves & Sound

v = f·λ

Wave speed equals frequency times wavelength.

v = Wave speed (m/s)

f = Frequency (Hz)

λ = Wavelength (m)

Period and Frequency

Waves & Sound

T = 1 / f

Period is the reciprocal of frequency.

T = Period (s)

f = Frequency (Hz)

Doppler Effect

Waves & Sound

f_obs = f_s · (v + v_obs) / (v + v_s)

Observed frequency when source or observer is moving. Use + for approaching, − for receding.

f_obs = Observed frequency (Hz)

f_s = Source frequency (Hz)

v = Speed of sound (m/s)

v_obs = Observer speed (m/s)

v_s = Source speed (m/s)

Snell's Law

Optics

n₁·sin(θ₁) = n₂·sin(θ₂)

Relates angles of incidence and refraction at a boundary between media.

n₁ = Refractive index 1 (dimensionless)

θ₁ = Angle of incidence (°)

n₂ = Refractive index 2 (dimensionless)

θ₂ = Angle of refraction (°)

Thin Lens Equation

Optics

1/f = 1/d_o + 1/d_i

Relates focal length to object and image distances.

f = Focal length (m)

d_o = Object distance (m)

d_i = Image distance (m)

Magnification

Optics

m = -d_i / d_o = h_i / h_o

Lateral magnification from image and object distances or heights.

m = Magnification (dimensionless)

d_i = Image distance (m)

d_o = Object distance (m)

h_i = Image height (m)

h_o = Object height (m)

Ideal Gas Law

Thermodynamics

PV = nRT

Relates pressure, volume, moles, and temperature of an ideal gas. R = 8.314 J/(mol·K).

P = Pressure (Pa)

V = Volume (m³)

n = Moles (mol)

R = Gas constant (J/(mol·K))

T = Temperature (K)

Heat Transfer (Q = mcΔT)

Thermodynamics

Q = m·c·ΔT

Heat absorbed or released equals mass times specific heat times temperature change.

Q = Heat (J)

m = Mass (kg)

c = Specific heat (J/(kg·K))

ΔT = Temperature change (K)

Linear Thermal Expansion

Thermodynamics

ΔL = α·L₀·ΔT

Change in length due to temperature change. α is the linear expansion coefficient.

ΔL = Change in length (m)

α = Expansion coefficient (1/K)

L₀ = Original length (m)

ΔT = Temperature change (K)

Thermal Efficiency

Thermodynamics

η = W / Q_h = 1 - T_c / T_h

Efficiency of a heat engine (Carnot limit).

η = Efficiency (dimensionless)

T_c = Cold temperature (K)

T_h = Hot temperature (K)

Ohm's Law

Electricity

V = I·R

Voltage equals current times resistance.

V = Voltage (V)

I = Current (A)

R = Resistance (Ω)

Electric Power

Electricity

P = V·I = I²·R = V²/R

Power dissipated in an electrical component.

P = Power (W)

V = Voltage (V)

I = Current (A)

R = Resistance (Ω)

Resistors in Series

Electricity

R_total = R₁ + R₂ + ... + Rₙ

Total resistance of resistors connected in series.

R_total = Total resistance (Ω)

R₁, R₂ = Individual resistances (Ω)

Resistors in Parallel

Electricity

1/R_total = 1/R₁ + 1/R₂ + ...

Total resistance of resistors connected in parallel.

R_total = Total resistance (Ω)

R₁, R₂ = Individual resistances (Ω)

Capacitor Charge

Electricity

Q = C·V

Charge stored in a capacitor equals capacitance times voltage.

Q = Charge (C)

C = Capacitance (F)

V = Voltage (V)

Coulomb's Law

Electricity

F = k·q₁·q₂ / r²

Electrostatic force between two charges. k = 8.99 × 10⁹ N·m²/C².

F = Force (N)

k = Coulomb constant (N·m²/C²)

q₁ = Charge 1 (C)

q₂ = Charge 2 (C)

r = Distance (m)

Electric Field

Electricity

E = F / q = k·Q / r²

Electric field strength at a distance r from charge Q.

E = Electric field (N/C)

F = Force (N)

q = Test charge (C)

Mirror Equation

Optics

1/f = 1/d_o + 1/d_i

Relates focal length to object and image distances for mirrors.

f = Focal length (m)

d_o = Object distance (m)

d_i = Image distance (m)

Index of Refraction

Optics

n = c / v

Refractive index is the ratio of speed of light in vacuum to speed in medium.

n = Refractive index (dimensionless)

c = Speed of light (m/s)

v = Speed in medium (m/s)

Mass-Energy Equivalence

Modern Physics

E = m·c²

Einstein's mass-energy equivalence. c = 3 × 10⁸ m/s.

E = Energy (J)

m = Mass (kg)

c = Speed of light (m/s)

Photon Energy

Modern Physics

E = h·f

Energy of a photon. h = 6.626 × 10⁻³⁴ J·s (Planck constant).

E = Energy (J)

h = Planck constant (J·s)

f = Frequency (Hz)

Frequently Asked Questions

What is the Physics Formula Lookup & Calculator?

The Physics Formula Lookup & Calculator is a free online tool that search 80+ physics formulas by topic with variable definitions and solve-for-any-variable calculator. It runs entirely in your browser with no installation or sign-up needed.

What topics are covered?

Mechanics, waves, thermodynamics, electricity & magnetism, and optics — covering most high school and intro college physics.

Can I use it as a calculator?

Yes — for most formulas you can enter known values and solve for any unknown variable.

Is it free?

Yes, completely free.

Is my data safe with this tool?

Absolutely. The Physics Formula Lookup & Calculator processes everything client-side in your browser. No data is uploaded to or stored on any server. Your content remains private on your device at all times.

Does the Physics Formula Lookup & Calculator work on mobile devices?

Yes, the Physics Formula Lookup & Calculator is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.

Do I need to create an account to use this tool?

No account or registration is needed. Simply open the Physics Formula Lookup & Calculator in your browser and start using it immediately. There are no sign-up walls or usage restrictions.

How do I use the Physics Formula Lookup & Calculator?

Simply enter your input in the provided field, adjust any settings to your preference, and the tool will process it instantly. You can then copy the result to your clipboard or download it.

Which browsers are supported?

The Physics Formula Lookup & Calculator works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.

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Free Physics Formula Lookup & Calculator is a free, browser-based tool in our Utility Tools collection. Everything runs locally on your device — no uploads, no sign-up, and your data stays private.

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