Type a value in the Gram (g) field and the equivalent in Microgram (μg) appears instantly to the right. The math uses the exact formula shown above — no rounding errors, no approximations beyond standard floating-point precision. Use the swap button to flip the units and see the inverse conversion.

Gram. One thousandth of a kilogram. About the weight of a paperclip.

Microgram. One millionth of a gram. Common in pharmacology and chemistry.

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No submit button — the result updates as you type. Math runs entirely in your browser, so it’s as fast as your device.

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🎯 Accurate conversions

Conversion factors come from the official standard (NIST, BIPM, ISO definitions where applicable). Values are precise to standard floating-point limits.

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How it works — the formula

value_in_base = value × scale
For mass, scale = kilograms per unit (e.g. 1 lb = 0.45359237 kg exactly)

The SI base unit for what laypeople call "weight" is the kilogram, redefined in 2019 in terms of the Planck constant h = 6.62607015 × 10⁻³⁴ J·s exactly (CGPM 26th meeting, Resolution 1). Strictly, weight is a force (mass × g) measured in newtons, but everyday usage and US-customary units treat it as mass. The international avoirdupois pound has been exactly 0.45359237 kg since the 1959 agreement.

Sources: BIPM — SI brochure, redefinition of the kilogram (2019) · NIST SP 811 §B.8 — Conversion factors for mass · NIST Handbook 44 — Mass standards

Worked examples

Example 1

Imperial → metric

Inputs:: 150 lb = ? kg
Output:: 150 × 0.45359237 = 68.0388555 kg

Example 2

Cooking conversion

Inputs:: 8 oz = ? g
Output:: 8 × 28.349523125 = 226.796185 g (avoirdupois)

Example 3

Tonne vs ton

Inputs:: 1 t (metric) = ? short ton
Output:: 1 / 0.90718474 ≈ 1.1023 short tons

Limitations

Avoirdupois ounce (28.349523125 g) differs from troy ounce (31.1034768 g, used for precious metals) — pick the right unit for context.
Short ton (US, 2,000 lb), long ton (UK, 2,240 lb), and tonne / metric ton (1,000 kg) all share the spelling "ton" — disambiguate carefully.
"Weight" on a scale is technically force; readings change by ~0.5% between equator and poles due to gravity, but local scales are calibrated to read mass.
Pharmaceutical and apothecary scales use yet another set of units (grain, drachm) — not modeled here.

Conversions assume mass; scale readings on Earth approximate mass to within local-gravity precision, which is more than sufficient for everyday use.

Frequently asked

What is the formula for converting Gram to Microgram?+

The formula is: 1 g = 1000000 μg. Type any value into the calculator above and the result appears instantly.

How do I convert Microgram back to Gram?+

Click the swap button (⇄) above to go to the Microgram → Gram converter, or use the inverse formula derived from the one shown.

How accurate is the conversion?+

Conversion factors used here are exact rational values from NIST SP 811 and the BIPM SI brochure (e.g. 1 ft = 0.3048 m exactly, 1 lb = 0.45359237 kg exactly). Trailing-digit differences vs hand calculation come only from binary floating-point representation, never from the conversion factor itself.

Where do these conversion factors come from?+

Length and mass factors come from the 1959 international yard-and-pound agreement; SI base units (metre, kilogram, second, kelvin) come from the 2019 BIPM redefinition; energy and pressure factors are NIST SP 811 reference values. Each editorial section above lists the specific source for that category.

Can I copy the conversion factor for use elsewhere?+

Yes. The factor in the formula above is the exact rational value used internally; copying it into Excel or another tool reproduces the result to floating-point precision.

Related weight tools

kg → lb lb → kg g → oz oz → g kg → g g → kg