1.5 inches equals 38.1 millimeters.
To convert 1.5 in to mm, multiply by 25.4 (since 1 inch = 25.4 mm). So, 1.5 × 25.4 = 38.1 mm. This conversion uses the exact length of an inch in millimeters.
Conversion Tool
Result in mm:
Conversion Formula
The formula for converting inches to millimeters is: millimeters = inches × 25.4. The number 25.4 is the fixed conversion factor that links inches to millimeters, since 1 inch equals exactly 25.4 millimeters. This means when you multiply any inch value by 25.4, you get its millimeter equivalent.
For example, converting 1.5 inches to millimeters step-by-step:
- Start with the inch value: 1.5
- Multiply by conversion factor: 1.5 × 25.4
- Calculate the product: 38.1
- Result is 38.1 millimeters
Conversion Example
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Convert 2.75 in to mm:
- Take 2.75 inches
- Multiply by 25.4: 2.75 × 25.4
- Calculate: 69.85 mm
- So, 2.75 in equals 69.85 mm
-
Convert 0.5 in to mm:
- Start with 0.5 inches
- Multiply by 25.4: 0.5 × 25.4
- Result: 12.7 mm
- Therefore, 0.5 in equals 12.7 mm
-
Convert 10 in to mm:
- Use 10 inches
- Multiply: 10 × 25.4
- Calculate: 254 mm
- 10 inches corresponds to 254 mm
-
Convert 7.2 in to mm:
- Start from 7.2 inches
- Multiply by 25.4: 7.2 × 25.4
- Result: 182.88 mm
- So, 7.2 in equals 182.88 mm
Conversion Chart
The following table lists inch values from -23.5 to 26.5, and their millimeter equivalents. Use the chart by locating the inch value you want and reading across to find the mm result.
| Inches (in) | Millimeters (mm) |
|---|---|
| -23.5 | -596.9 |
| -20.0 | -508.0 |
| -15.0 | -381.0 |
| -10.5 | -266.7 |
| -7.0 | -177.8 |
| -3.3 | -83.82 |
| 0 | 0 |
| 3.5 | 88.9 |
| 6.0 | 152.4 |
| 9.8 | 248.92 |
| 12.2 | 309.88 |
| 16.7 | 424.18 |
| 20.0 | 508.0 |
| 23.0 | 584.2 |
| 26.5 | 673.1 |
Related Conversion Questions
- How many millimeters are in 1.5 inches exactly?
- What is 1.5 inch in millimeter rounded to two decimals?
- Why multiply inches by 25.4 to get millimeters?
- Can 1.5 in be converted to mm without a calculator?
- Is 38.1 mm the exact conversion of 1.5 inches?
- How to convert fractional inches like 1.5 to millimeters?
- What formula to use for 1.5 in to mm conversion?
Conversion Definitions
In (inch): Inch is a unit of length in the Imperial and United States customary systems. It equals exactly 1/12 of a foot and is defined as 25.4 millimeters. Inches are used mainly in the US, UK, and Canada for measuring small distances or object sizes.
Mm (millimeter): Millimeter is a metric unit of length equal to one thousandth of a meter (0.001 m). It is widely used around the world for precise measurements in engineering, manufacturing, and everyday measurements smaller than a centimeter.
Conversion FAQs
Can I convert inches to millimeters by just multiplying by 25?
Multiplying inches by 25 gives an approximate result but is inaccurate. The exact factor is 25.4, so multiplying by 25.4 ensures precise conversion. Using 25 would cause a small error, which might be unacceptable in precise measurements.
Why is the inch defined as exactly 25.4 millimeters?
The inch was standardized internationally in 1959 to be exactly 25.4 mm to unify measurement systems. Before, variations existed between countries. This exact definition allows consistency across engineering, manufacturing, and scientific fields.
Is it possible to convert negative inch values to millimeters?
Yes, negative inch values represent measurements below a reference point or direction. The conversion works the same by multiplying the negative inch value by 25.4, resulting in a negative millimeter value, preserving the negative sign.
How precise is the conversion from inches to millimeters?
The conversion using 25.4 is exact by definition. Precision depends on how many decimal places you keep when calculating, but the fundamental conversion factor is exact. Calculators or software may round results based on display settings.
If I have 1.5 inches, how can I quickly estimate millimeters without a calculator?
You can approximate 1 inch as 25 mm, so 1.5 inches is about 37.5 mm. While close, the exact value is 38.1 mm. For rough estimates, this works, but for exact measurements use 25.4 as the multiplier.
