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Unit Converter

Convert length, weight, temperature, area, and volume.

Conversion ToolsUpdated 2026-04-05• Author: CalcDock Team, Measurement reference editor• Reviewed by: CalcDock Team, Editorial review: SI / NIST conversion factors (Apr 2026)

Convert between metric and imperial units across length, weight, temperature, area, and volume with instant results.

When this calculator helps most

Use for standard SI ↔ US customary conversions when dimensions are clear — homework, travel, cooking, and rough engineering estimates.

What each input means

Value — Numeric amount in the source unit before conversion. (number)
From / To — Pick consistent pair (e.g. km→mi); area/volume modes expect squared/cubed semantics in the UI. (unit id)

Input mistakes to avoid

•Square or cube the length factor for area/volume — do not reuse linear factors.
•Temperature: use the dedicated formula, not a ratio.

Unit Converter

From

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Formula

Unit conversion is done by converting the input to a base unit, then from the base to the target unit using fixed factors (e.g., 1 in = 2.54 cm). Temperature uses specific formulas (°F = °C × 9/5 + 32).

Examples

Body Weight: 70 kg → lb

Convert kilograms to pounds.

→ 70 kg = 154.323 lb

Room Length: 3 m → ft

Convert meters to feet.

→ 3 m = 9.84252 ft

How to read your results

→Length, mass, and most SI↔USCustomary conversions are linear multiplications by an exact factor.
→Area and volume need squared or cubed factors — never reuse a length factor twice by mistake.
→Temperature uses an affine map (°F, °C, K), not a single ratio like miles to km.

What this result means

Output is deterministic from fixed conversion factors — still verify critical doses or safety limits with primary sources.

Common Pitfalls

⚠️Using the linear factor for area/volume — square it for area (ft² ↔ m²) and cube it for volume (ft³ ↔ m³).
⚠️Treating temperature like a ratio — Celsius ↔ Fahrenheit requires add/multiply formulas, not simple multiplication.
⚠️Mixing mass and volume in recipes — grams convert to ml only using density; do not assume 1 g = 1 ml except for water.
⚠️Rounding too aggressively — keep precision through intermediate steps, round for display.

Tips

✓Swap units with the ⇄ button to reverse conversion.
✓Temperature conversions use formulas, not fixed ratios.

How to check your results

✓Known anchors: 1 in = 2.54 cm exactly; 1 lb ≈ 0.453592 kg.

Warnings & Limitations

⚠️Conversion factors can be context‑specific (US vs Imperial gallon, room temperature assumptions).
⚠️Round for display only — keep sufficient precision internally for chained conversions.

What this calculator does not tell you

–Which US gallon (liquid vs dry) a legacy label means — pick the mode the recipe or spec uses.
–Relativistic or extreme-precision metrology — NIST-level uncertainty budgets.

Frequently Asked Questions

How do I convert Celsius to Fahrenheit?

Use °F = (°C × 9/5) + 32. For example, 20°C = 68°F.

How many kilometers are in a mile?

1 mile = 1.60934 kilometers. Conversely, 1 km = 0.62137 miles.

Sources & References

Report an issue with this calculator

Editorial & review note

SI and US customary factors follow reference definitions; affine conversions (°C/°F) are labeled separately from linear length/mass. Kitchen volume ↔ mass still needs ingredient density—outside this tool’s scope.

Editorial Policy