F L

Factor-Label Method

Interactive Unit Conversion

How It Works

The factor-label method (dimensional analysis) converts between units by multiplying by conversion factors arranged as fractions. The key insight: set up the fraction so the unwanted unit cancels and the desired unit remains.

Starting Value × Desired Unit Starting Unit = Converted Value

Step-by-Step Examples

Cups to Liters

1 cup = 0.2366 L

Teaspoons to Milliliters

1 tsp = 4.929 mL

Kilograms to Pounds

1 kg = 2.2046 lb

Try Your Own

Enter a value and pick a conversion to see the step-by-step process.

Flipping the Conversion Factor

Putting the wrong unit on top of the fraction. The unit you want to cancel must be on the opposite side of the fraction from where it appears in your starting quantity.

Wrong: 3 cups × (1 cup / 0.2366 L) ← cups don't cancel!
Right: 3 cups × (0.2366 L / 1 cup) ← cups cancel ✓
Forgetting to Multiply or Divide

Setting up the fraction correctly but then forgetting to actually perform the arithmetic. After the units cancel, you still need to multiply (or divide) the numerical values.

3 × (0.2366 / 1) = 0.7098, not just "0.2366 L"
Mixing Metric and Imperial in a Chain

When chaining multiple conversion factors, accidentally using a metric-to-metric factor where you need metric-to-imperial (or vice versa). Each step must bridge the correct unit pair.

Need: kg → lb, not kg → g → lb using wrong factor
Not Verifying That Units Cancel

Always check: does the unwanted unit appear once in the numerator and once in the denominator? If not, your setup is wrong. Write out the full expression and visually confirm the cancellation before computing.

Check: cups (top) × L / cups (bottom) → cups cancel ✓ → L remains ✓