mg/g to g/kg Converter
50 mg/g and 50 g/kg are exactly the same amount, so the number does not change.
Quick answer: Keep the number the same and change only the unit label. For example, 10 mg/g is 10 g/kg, 50 mg/g is 50 g/kg and 250 mg/g is 250 g/kg.
The mg/g to g/kg formula
The value in g/kg equals the value in mg/g, times 1.
Both units describe one part in 1,000 by weight.
Take 10 mg/g. 10 × 1 gives 10 g/kg.
Take 50 mg/g. 50 × 1 gives 50 g/kg.
Why the number stays put
A milligram is one thousandth of a gram, and a gram is one thousandth of a kilogram. In mg/g the top is divided by 1,000 and the bottom is not, and in g/kg the bottom is multiplied by 1,000 and the top is not.
Both give 1 part in 1,000, which is also called parts per thousand (Wikipedia: Parts-per notation).
How to convert mg/g to g/kg step by step
- Read the value in mg/g.
- Write the same number with the unit g/kg.
- Divide by 10 if you want percent by weight.
- Check that both units are mass per mass, not per volume.
Example 1: 10 mg/g
- Start with 10 mg/g.
- 10 × 1 = 10.
- The g per kg is 10 g/kg.
10 mg/g = 10 g/kg
Example 2: 50 mg/g
- Start with 50 mg/g.
- 50 × 1 = 50.
- The g per kg is 50 g/kg.
50 mg/g = 50 g/kg
Example 3: 250 mg/g
- Start with 250 mg/g.
- 250 × 1 = 250.
- The g per kg is 250 g/kg.
250 mg/g = 250 g/kg
The three examples below use common sizes.
Each one shows the sum in full.
mg/g to g/kg conversion table
| Concentration | g per kg | Percent by weight |
|---|---|---|
| 0.5 mg/g | 0.5 g/kg | 0.05 percent |
| 1 mg/g | 1 g/kg | 0.1 percent |
| 5 mg/g | 5 g/kg | 0.5 percent |
| 10 mg/g | 10 g/kg | 1 percent |
| 20 mg/g | 20 g/kg | 2 percent |
| 50 mg/g | 50 g/kg | 5 percent |
| 75 mg/g | 75 g/kg | 7.5 percent |
| 100 mg/g | 100 g/kg | 10 percent |
| 150 mg/g | 150 g/kg | 15 percent |
| 250 mg/g | 250 g/kg | 25 percent |
| 500 mg/g | 500 g/kg | 50 percent |
| 1,000 mg/g | 1,000 g/kg | 100 percent |
The highlighted row is the default of the calculator. The last column gives percent.
A quick mental shortcut for mg/g to g/kg
The number is the same in both units. So 75 mg/g is 75 g/kg.
Double the mg/g value and the g/kg value doubles.
A quick proof
Take 1 mg in 1 g. That is 0.001 g in 1 g, which is the same as 1 g in 1,000 g.
And 1,000 g is 1 kg, so 1 mg/g is 1 g/kg.
Worked examples
A value of 10 mg/g is 10 g/kg, and a value of 250 mg/g is 250 g/kg. A value of 1,000 mg/g is 1,000 g/kg, which means the sample is all one substance.
A value of 0.5 mg/g is 0.5 g/kg.
Feed and food reports
Feed and food reports often give nutrients in g/kg, while labels may use mg/g or percent. A report of 180 g/kg is the same as 180 mg/g, which is 18 percent.
A 3 kg batch at 180 g/kg holds 540 g of the nutrient.
Same family of units
Several units share this ratio, including mg/g, g/kg and ug/mg. They all mean 1 part in 1,000 by weight.
Only the percent and ppm forms need a number change.
Per mass, not per volume
Both units are mass per mass. A unit such as mg/mL is mass per volume, and it needs the density of the liquid to convert.
The mg/g to mg/mL page shows that extra step.
Quick conversion answers
| Conversion | Result |
|---|---|
| 50 mg/g | 50 g/kg |
| 10 mg/g | 10 g/kg |
| 250 mg/g | 250 g/kg |
| 1,000 mg/g | 1,000 g/kg |
Where this conversion is used
Readers of feed, food and lab reports switch between unit styles.
Students practise unit prefixes.
Common mistakes to avoid
- Changing the number. The number stays the same.
- Mixing up g/kg and g/L. The second is per volume.
- Forgetting the percent step. Divide by 10 for percent.
- Mixing mg/g with mg/kg. They differ by a factor of 1,000.
Related converters
More mg/g values
2 mg/g is 2 g/kg. 8 mg/g is 8 g/kg. 15 mg/g is 15 g/kg.
30 mg/g is 30 g/kg. 40 mg/g is 40 g/kg. 60 mg/g is 60 g/kg.
180 mg/g is 180 g/kg. 400 mg/g is 400 g/kg. 800 mg/g is 800 g/kg.
Doubling the first number
4 mg/g is 4 g/kg. 16 mg/g is 16 g/kg. 30 mg/g is 30 g/kg.
60 mg/g is 60 g/kg. 80 mg/g is 80 g/kg. 120 mg/g is 120 g/kg.
360 mg/g is 360 g/kg. 800 mg/g is 800 g/kg. 1,600 mg/g is 1,600 g/kg.
Going to ppm and mg/kg
One mg/g equals 1,000 mg/kg, and it also equals 1,000 ppm for a mass ratio. So 50 mg/g is 50,000 mg/kg and 50,000 ppm.
These forms need a number change, while g/kg does not.
Scaling a batch
A batch at 50 g/kg holds 50 g of the substance in every kg. So a 2 kg batch holds 100 g, and a 500 g batch holds 25 g.
The same sums work at 50 mg/g, because the two units are the same.
Comparing two reports
Report A says 60 g/kg and report B says 45 mg/g. Since 45 mg/g is 45 g/kg, report A is 15 g/kg higher.
Report A is also about 1.33 times report B. Writing both in one unit makes the gap easy to see.
A rule to remember
Milli means a thousandth and kilo means a thousand. A milli unit over a base unit gives one thousandth, and a base unit over a kilo unit also gives one thousandth.
So whenever you see mg/g next to g/kg, you can swap them freely. A value of 5 mg/g is 5 g/kg, which is 0.5 percent.
mg/g to ug/mg as well
The unit ug/mg gives the same number as mg/g and g/kg. So 50 mg/g is 50 g/kg and also 50 ug/mg.
The sections below cover where ug/mg appears and how to read its prefix.
Where ug/mg appears
Lab reports sometimes give an amount per mg of tissue, powder or extract in ug/mg. Product labels may use mg/g for the same ratio.
This page only changes the unit label. It gives no advice on what any result means.
Check the prefix
The letter u stands for the Greek letter mu, which means micro. Do not read ug as mg.
If a value was meant to be mg/mg, it would be a plain ratio with no unit.
Scaling a sample
A strength of 50 ug/mg means 50 ug in every mg. So 20 mg of powder holds 1,000 ug, which is 1 mg, and 250 mg holds 12,500 ug, which is 12.5 mg.
The same sums work at 50 mg/g, because the two units are the same.
Frequently asked questions
How do I convert mg/g to g/kg?
Keep the number and change the unit.
What is 50 mg/g in g/kg?
50 g/kg.
Why are they the same?
Both mean 1 part in 1,000 by weight.
How do I get percent?
Divide the value by 10.
Is mg/g the same as mg/kg?
No. mg/kg is 1,000 times smaller.
Does it work for liquids?
Only for mass per mass. Use density for volume units.
Sources
- Wikipedia: Parts-per notation (en.wikipedia.org)
