Convert along the full metric ladder from micrograms to tonnes. Every step is an exact power of ten, and the page teaches the prefix system rather than hiding it.
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What this converter does
It converts between all ten rungs of the metric mass ladder in any combination: microgram, milligram, centigram, decigram, gram, decagram, hectogram, kilogram, quintal and tonne. Every step is a power of ten, so every conversion is exact, and the table shows your value in all ten units at once.
Why every conversion here is exact
Because the prefixes are definitions rather than measurements. Milli means a thousandth and kilo means a thousand by international agreement, so converting between them moves a decimal point and introduces no error whatsoever. This is a different kind of exactness from the cross-system conversions elsewhere in this cluster, which are also exact but only because the pound was legally defined in kilograms in 1959. Here the exactness is structural: it could not have been otherwise.
The ladder in order
From smallest: microgram, milligram, centigram, decigram, gram, decagram, hectogram, kilogram. Micro to milli is a factor of a thousand. The four rungs around the gram step by ten each. Gram to kilogram is a thousand again. Above the kilogram, the quintal at 100 kg and the tonne at 1,000 kg extend the ladder for agricultural and freight quantities. One gram is 1,000,000 micrograms and 0.000001 tonnes, spanning twelve orders of magnitude across the whole set.
Which rungs people actually use
Milligram, gram, kilogram and tonne do nearly all the work, with the microgram in medicine and trace analysis. Centigram and decigram are essentially schoolwork units with no current practical application, which the individual pages for them say plainly. The decagram is ordinary in Central European shops, the hectogram in Italian ones, and the quintal in Indian agricultural markets — each genuinely used, each regionally. Knowing which is which prevents both over-claiming and dismissing a unit that is entirely normal somewhere.
Greek and Latin in the prefix names
The multiplying prefixes take Greek roots — deca, hecto, kilo, mega — and the dividing prefixes take Latin ones — deci, centi, milli. So a Greek root makes the unit bigger and a Latin root makes it smaller. That resolves the deci-versus-deca confusion, since the two sound alike because both descend from words for ten, but one divides and one multiplies. The convention was deliberate when the system was drawn up in the 1790s and it holds throughout the modern SI.
Converting several rungs at once
Pick the two units directly rather than stepping through the intermediates. Micrograms to kilograms in one operation is a single shift of nine decimal places; chaining three separate conversions gives three chances to drop a factor of a thousand, which is the error that actually happens. The multi-unit table on this page shows every rung simultaneously for the same reason — seeing the whole ladder at once makes a misplaced magnitude obvious.
Is the tonne an SI unit?
Not strictly. The kilogram is the SI base unit for mass, and the tonne is accepted for use alongside the SI rather than forming part of it. The distinction has no practical consequence, since a tonne is exactly 1,000 kg everywhere, but it explains why formal documents sometimes prefer to write kilograms and why the tonne carries no SI prefix of its own — a thousand tonnes is a kilotonne by convention rather than by the strict rules.
Scientific notation
The display switches to scientific form past about ten to the fifteenth and below about a millionth, where plain decimals become a zero-counting exercise. You can force either notation from the Display control. Neither is more accurate — they are the same exact value in two presentations — but the scientific form is markedly less error-prone when a number is feeding further calculation.
Common mistakes
Confusing deci with deca, which differ by one letter and a factor of a hundred. Chaining conversions and losing a factor of a thousand. Assuming an unfamiliar prefix must be small. And treating a metric conversion as though it might be approximate — within this ladder, nothing is, and a disagreement between two correct answers is always a display difference.
Benchmarks
1 g is 1,000,000 micrograms, 1,000 mg, 100 cg, 10 dg, 0.1 dag, 0.01 hg, 0.001 kg. 1 kg is 1,000 g and 0.001 t. 1 quintal is 100 kg. 1 tonne is 1,000 kg and 10 quintals. Those relationships reconstruct the entire ladder without a table.
Accuracy and limits
Exact factors throughout, exact decimal arithmetic, display-only rounding, and refusal of ambiguous input with an explanation. The tool converts metric mass; imperial and troy units have their own converters in this cluster, deliberately kept separate so the constants never blur.
What the kilogram is now
Until 2019 the kilogram was a physical object: a platinum-iridium cylinder held near Paris, with every mass measurement on Earth traceable to whatever that artefact happened to weigh, drift included. The 2019 redefinition fixed the numerical value of the Planck constant instead, making the kilogram reproducible from physics in any properly equipped laboratory rather than by comparison with a lump of metal. No conversion on this page changed, because the relationships between metric units are ratios and ratios survive redefinitions untouched.
Why the base unit has a prefix
The kilogram is the only SI base unit whose name carries a prefix, which is a historical accident rather than a design choice — the gram was originally the base and the kilogram proved the more practical size. The consequence is a small irregularity: prefixes attach to the gram rather than to the kilogram, so a thousandth of a kilogram is a gram rather than a millikilogram. Every metric mass conversion works around that quirk without difficulty, but it explains why the ladder on this page is built on the gram.
Checking a metric conversion
Count the decimal places between the two units and compare against the answer. Converting to a larger unit must give a smaller number and vice versa, which sounds too obvious to state and is exactly what a factor-of-ten error violates. Since every conversion here is a pure decimal shift, a wrong answer is always a miscounted number of places or a reversed direction rather than an arithmetic slip — which makes metric errors easier to diagnose than cross-system ones.
How to use the Metric Weight Converter
- Enter a value and choose its metric unit.
- Pick the target unit anywhere on the ladder from micrograms to tonnes.
- Every step is an exact power of ten.
- The table shows your value in all ten metric units at once.
Frequently asked questions
Which units does this converter cover?
The full metric ladder for mass: microgram, milligram, centigram, decigram, gram, decagram, hectogram, kilogram, quintal and tonne. Ten rungs, every step a power of ten, and every conversion between them exact.
Why are all metric conversions exact?
Because the prefixes are definitions rather than measurements. Milli- means a thousandth and kilo- means a thousand, by agreement, so converting between them moves the decimal point and introduces no error whatsoever. Cross-system conversions to pounds and ounces are also exact, but for a different reason — the pound was defined in kilograms in 1959.
What order do the prefixes go in?
From smallest: micro, milli, centi, deci, then the gram, then deca, hecto, kilo. Micro to milli is a factor of a thousand; the four rungs either side of the gram step by ten; gram to kilogram is a thousand again. The quintal at 100 kg and the tonne at 1,000 kg extend the ladder upward.
Which of these units are actually used?
Milligram, gram, kilogram and tonne do nearly all the work, with the microgram in medicine and trace analysis. Centigram and decigram are essentially schoolwork units. The decagram is ordinary in Central Europe, the hectogram in Italy, and the quintal in Indian agriculture — each genuinely used, but regionally.
Is the tonne an SI unit?
Not strictly. The kilogram is the SI base unit for mass, and the tonne is accepted for use alongside the SI rather than being part of it. That distinction has no practical consequence — a tonne is exactly 1,000 kg everywhere — but it explains why official documents sometimes prefer to write kilograms.
How do I convert several rungs at once?
Pick the two units directly rather than stepping through the intermediates. Going from micrograms to kilograms in one operation is a single shift of nine decimal places, where chaining three conversions gives three chances to drop a factor of a thousand.
When does the display switch to scientific notation?
Past about ten to the fifteenth, and below about a millionth, where plain decimals become a zero-counting exercise. You can force either notation from the Display control if a form or a calculation needs one specifically.
