Why Accurate Mass Conversion Matters in the Lab

Precise mass measurements and unit conversions are foundational to quantitative chemistry. Using the wrong unit multiplier (e.g., confusing µg with mg) can lead to thousand-fold errors in reagent amounts, affecting reaction yields, analytical calibration, and safety.

How to Use This Converter

Enter the numerical mass value in the input field. Use scientific notation (e.g., 2.5e-4) if needed.
Select the unit you are converting from and the unit you are converting to.
If converting to or from moles, enter the molar weight (molecular weight) of the compound in g/mol.
Click "Calculate Conversion". The result, intermediate steps, and quick equivalents will update instantly.
Use the "Swap Units" button to reverse the conversion direction.

Realistic Examples

Weighing a protein sample: Your balance reads 0.254 mg. Convert to µg → 254 µg.
Preparing a buffer: Recipe calls for 2.5 g of Tris. Convert to mg → 2500 mg.
Pharmacology dosing: A drug is dosed at 150 µg/kg. For a 70 kg patient, total dose = 10,500 µg = 10.5 mg.
Synthesis: You need 0.005 mol of benzoic acid (MW 122.12 g/mol). Mass = 0.6106 g = 610.6 mg.

Common Conversion Factors (Exact Definitions)

Unit	Equivalent in Grams	Notes
1 kg	1000 g	SI base unit
1 g	1 g	Reference
1 mg	0.001 g	Milli = 10⁻³
1 µg	1e-6 g	Micro = 10⁻⁶
1 lb (avoirdupois)	453.59237 g	Exact by definition
1 oz	28.349523125 g	1/16 lb

Common Mistakes Checklist

Confusing µg (micrograms) with mg (milligrams) – a 1000× error.
Using an outdated or approximate molar weight (always use current IUPAC values).
Forgetting to account for purity (%) of the solid reagent.
Assuming "ounce" means fluid ounce (volume) instead of mass ounce.
Not taring the balance correctly before weighing.

Frequently Asked Questions

What is the difference between mass and weight?

Mass is the amount of matter (constant everywhere). Weight is the force of gravity on that mass (varies with location). In lab contexts, we usually measure mass using balances calibrated with standard weights.

Why does the mole conversion require molar weight?

A mole is an amount of substance (number of particles), not a mass. Converting between mass and moles requires the molar mass (g/mol) of the specific compound.

Are the conversions exact?

Metric conversions (g↔mg↔µg↔kg) are exact powers of ten. Pound and ounce conversions use exact definitions (1 lb = 0.45359237 kg exactly). Mole conversions depend on the accuracy of the molar weight you provide.

What precision should I use for lab work?

Match the precision of your measurement device. Analytical balances often read to 0.1 mg (0.0001 g). Use 4–6 decimal places for grams in such cases. For rough prep, 2–3 decimals may suffice.

Mass Unit Converter

Conversion Result

Intermediate Steps & Notes

Quick Equivalents (for the input mass above)

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Mass Unit Converter for Lab

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