SI prefix converter
Convert deci to base unit
1 d = 0.1 unit — to convert deci to base unit, divide by 10.
Deci to base unit calculator
1 d = 0.1 unit
Deci to base unit at a glance
1 d = 0.1 unit
÷ 10
1 place left
10⁻¹ → 10⁰
Deci to base unit formula and conversion factor
Every SI prefix is a whole power of ten. Deci is 10⁻¹ of the base unit and base unit is 10⁰, so the two are exactly 1 power of ten apart. That makes the factor exactly 10 — not an approximation, and it never changes with the unit you are measuring.
unit = d ÷ 10
10⁻¹ ÷ 10⁰ = 10⁻¹ = 0.1
1 d = 0.1 unit
5 d = 0.5 unit
100 d = 10 unit
1000 d = 100 unitDeci to base unit conversion table
The values people look up most often, converted exactly. Read down for deci (d), across for base unit (unit).
In words: 10 d is 1 unit, 100 d is 10 unit, 500 d is 50 unit, 1000 d is 100 unit, 2000 d is 200 unit, and 5000 d is 500 unit.
| Deci (d) | Base unit (unit) |
|---|---|
| 0.0009 d | 0.00009 unit |
| 0.001 d | 0.0001 unit |
| 0.005 d | 0.0005 unit |
| 0.008 d | 0.0008 unit |
| 0.01 d | 0.001 unit |
| 0.02 d | 0.002 unit |
| 0.05 d | 0.005 unit |
| 0.1 d | 0.01 unit |
| 0.2 d | 0.02 unit |
| 0.4 d | 0.04 unit |
| 0.5 d | 0.05 unit |
| 1 d | 0.1 unit |
| 2 d | 0.2 unit |
| 5 d | 0.5 unit |
| 7 d | 0.7 unit |
| 10 d | 1 unit |
| 20 d | 2 unit |
| 50 d | 5 unit |
| 100 d | 10 unit |
| 200 d | 20 unit |
| 250 d | 25 unit |
| 300 d | 30 unit |
| 400 d | 40 unit |
| 500 d | 50 unit |
| 800 d | 80 unit |
| 1,000 d | 100 unit |
| 2,000 d | 200 unit |
| 5,000 d | 500 unit |
How to convert deci to base unit without a calculator
Move the decimal point 1 place to the left, padding with zeros if you run out of digits. Going to a larger prefix always makes the number smaller, because each unit now covers more of the quantity.
The check that catches almost every mistake: compare the two exponents before you write the answer. Deci is 10⁻¹, base unit is 10⁰. If the prefix you are moving to is smaller, the digits must grow. If your answer moved the wrong way, you divided when you should have multiplied — the failure mode behind more than one real unit-conversion incident.
“Normal units”, base units, and plain units
A base unit is the unprefixed unit — amperes, grams, seconds, metres, litres. It is the same thing people mean by “normal units”, “plain units”, or just “units”: converting micro to normal, micro to unit, and micro to base unit are all the same calculation. There is no separate rule for it, because the base unit is simply the prefix 10⁰.
One place the wording matters: in medicine a “unit” can be a dose unit rather than an SI base unit — insulin is dosed in units and milliunits, and thyroid labs report µIU/mL. The prefix math is identical (1 unit = 1,000 milliunits), but the “unit” there is a biological activity unit, not a metre or a gram.
Deci to base unit FAQ
- How do you convert deci to base unit?
- To convert deci to base unit, divide by 10. That is the same as moving the decimal point 1 place to the left. For example, 1 d = 0.1 unit, and 5 d = 0.5 unit.
- How many deci are in 1 base unit?
- There are exactly 10 deci in 1 base unit. Base unit (unit) is 10⁰ of the base unit and deci (d) is 10⁻¹, so they sit 1 power of ten apart — a factor of exactly 10, with no rounding.
- Is 1 deci equal to 1 base unit?
- No. Deci and base unit are different SI prefixes 1 power of ten apart. Deci is 10 times smaller than base unit, so 1 d = 0.1 unit.
- Is the deci to base unit conversion exact?
- Yes. Every SI prefix is a whole power of ten, so deci to base unit is exactly ÷ 10 with no rounding. This calculator shifts the decimal exponent instead of multiplying in binary floating point, so a value like 1.001 d returns an exact result rather than one with a trailing rounding error.
- Is deci bigger or smaller than base unit?
- Deci is smaller. Deci is 10⁻¹ and base unit is 10⁰, which makes deci 10 times smaller. The number always moves the other way: a quantity written in the smaller unit uses the bigger number.