Lever mechanical advantage calculator

Ideal two-arm lever perpendicular to force.

statics-lever.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

Scenario	effortN	advantage
	25	4
	20	4

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

effort budget25.00 N✓ passes

BASELINE INPUTS

load100 NloadArm50 mmeffortArm200 mm

CALCULATED

effort25 N

advantage4

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Lever mechanical advantage
# Scope: Ideal two-arm lever perpendicular to force.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

load = 100 N
loadArm = 50 mm
effortArm = 200 mm

effort := load*loadArm/effortArm [N]
advantage := effortArm/loadArm

check effort budget: effort <= 40 N

scenario alternative: load = 80 N

Calculated from your source · not saved

Baseline · Baseline

effort budget25.00 N ✓ passes

alternative · alternative

effort budget20.00 N ✓ passes

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

effort: effort = load*loadArm/effortArm [N]
advantage: advantage = effortArm/loadArm

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

load: 100 N
load arm: 50 mm
effort arm: 200 mm

Calculated

effort: 25 N
advantage: 4

Assumptions and limits

Ideal two-arm lever perpendicular to force.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Lever mechanical advantage. Inputs: lever arms; applied force. Outputs: output force; travel tradeoff. Model scope: Rigid-body, quasistatic equilibrium. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

Inputs: lever arms, applied force
Outputs: output force, travel tradeoff
Modes: calculate, compare, sweep
Drawing: Free-body diagram

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS