Four modes, zero guesswork.
Pick a tab and type your values — everything recalculates live as you type, and every result shows the formula and the numbers behind it.
The push or pull — 150 N slides a heavy box, about 1 N lifts a small apple.
How far the object moves while the force acts — 8 m of floor, 2 m of ramp.
0° pushes straight along the motion · 90° is sideways (zero work) · 180° pushes against it (negative work).
The object being pushed or braked — a small car is about 1,200 kg.
Speed before the push — 0 if the object starts at rest.
Speed after it — bigger than v₁ means positive work, smaller means braking.
What you’re lifting — 10 kg is about a full bucket of water.
The vertical distance raised — 2 m is a tall shelf, 3 m a flight of stairs.
Where the lifting happens — pick a world, or enter your own g.
Any positive value — 3.7 for Mars, or 12 for a stronger fictional world.
Pick what you want out — the other two become the inputs.
Energy in or out — 2,000 J lifts a 100 kg mass about 2 m.
How long the work takes, or how long the power runs.
The rate of transfer — 100 W is a bright old bulb, 2,000 W a kettle.
Question to answer in under a minute.
A thirty-second tour, in case you like knowing exactly what will happen.
Pick your mode
Four tabs: force & distance, work-energy, lifting, or power. Each one is a full calculator with its own examples.
Type what you know
Enter values and choose units from the dropdowns — newtons or pound-force, metres or feet. Everything converts automatically.
Watch it solve live
Results update as you type: the big answer, the formula with your numbers substituted in, and conversions to kJ, calories and watt-hours.
Copy or learn
One click copies the full working. Impossible inputs get a friendly explanation instead of a wrong answer.
Every mode, one line each.
The four formulas this calculator runs on — plus two rearrangements you’ll meet in homework.
Work from force
Force × displacement × the cosine of the angle between them. A 150 N push along 8 m of floor does 1,200 J.
Work-energy theorem
Net work equals the change in kinetic energy — speeding up is positive work, braking is negative.
Lifting work
Raising 10 kg by 2 m on Earth takes 10 × 9.81 × 2 ≈ 196 J — exactly the potential energy gained.
Power
Work per unit of time, in watts. Delivering 1,000 J in 10 s means 100 W of power.
Solving for force
The rearrangement for when the work is known — say, putting 600 J into a 4 m push at 0°.
The joule
One joule is a one-newton push over one metre — roughly lifting an apple up to table height.
Work, minus the confusion.
The questions that come up in every physics class, answered in plain language with the numbers to back them up.
What is the formula for work done?+
Work equals force × displacement × the cosine of the angle between them: W = F · d · cos θ. Pushing a box with 150 N across 8 m of floor (force straight along the motion, θ = 0°) does W = 150 × 8 × 1 = 1,200 J. Whenever force is in newtons and distance in metres, work comes out in joules.
When is work done equal to zero?+
Three ways: the force is zero, the displacement is zero, or the force is perpendicular to the motion (θ = 90° or 270°, where cos θ = 0). The last one is the classic trap — carrying a heavy bag horizontally at constant speed does zero work on it, because the upward supporting force never acts along the horizontal motion.
Why does the work formula include cos θ?+
Only the component of the force that points along the displacement does any work, and that component is F · cos θ. Pulling a sled with a rope angled 30° above the ground, only cos 30° ≈ 0.866 of the pull moves the sled forward — the rest just lifts slightly. Enter the angle and the calculator applies the cosine automatically.
Can work be negative?+
Yes. Whenever the force has a component opposing the motion (90° < θ < 270°), cos θ is negative and so is the work. Friction acting on a sliding box does negative work, and so do brakes — they remove kinetic energy instead of adding it. Negative work is how moving things slow down.
What is the work-energy theorem?+
The total (net) work done on an object equals its change in kinetic energy: W = ½m·v₂² − ½m·v₁². Speeding a 1,200 kg car from rest to 20 m/s takes ½ × 1200 × 20² = 240,000 J of work; braking it back to rest gives net work of −240,000 J.
How do I calculate the work done against gravity?+
Use W = m · g · h — mass × gravitational acceleration × height. Lifting 10 kg through 2 m on Earth takes 10 × 9.81 × 2 ≈ 196 J, exactly the gravitational potential energy gained. Lowering the same mass gives the same amount back as negative work.
What is the difference between work and power?+
Work is an amount of energy transferred, measured in joules; power is how fast it is transferred, measured in watts (1 W = 1 J per second). Climbing the same staircase does the same work whether you sprint or stroll — only the power output differs. The calculator’s Power mode converts between work, power and time.
What units does work use, and how do I convert them?+
The SI unit is the joule: 1 J = 1 N·m. Common conversions: 1 kJ = 1,000 J, 1 cal = 4.184 J, 1 kcal = 4,184 J, 1 Wh = 3,600 J, 1 ft·lbf ≈ 1.356 J. The calculator converts every result into these units automatically.
Is this calculator free, and is my data sent anywhere?+
It is completely free and runs entirely in your browser — nothing you type is uploaded, logged or sent to a server. No account, no sign-up, no limits.