How to use this calculator
Select the calculation mode that matches your real measurement problem. Enter positive dimensions, choose their units, and select a container shape or material. The calculator converts every value internally before applying the correct formula.
Use liquid mode when millimeters describe a liquid depth inside a known container. Use material mode when millimeters describe an object whose density is known. Use copper mode for printed circuit boards, copper foil, or sheet coatings.
Review the primary result, alternative units, formula, substituted values, and calculation steps. Adjust decimal precision when comparing engineering values. Export the result as CSV or use the print button to save a PDF.
Why millimeters cannot directly convert to ounces
A millimeter measures length, while an ounce usually measures mass. A fluid ounce measures volume instead. A direct conversion is impossible unless the container geometry, material density, or another physical relationship is known.
For liquids, the calculator uses depth together with the container cross section. This creates a volume in cubic millimeters. The volume is then converted to milliliters and finally into US or UK fluid ounces.
For solid materials, the calculator first determines object volume. It multiplies volume by density to calculate mass. The resulting grams are converted into avoirdupois ounces, troy ounces, pounds, and kilograms.
Formula used
| Calculation | Formula | Purpose |
|---|---|---|
| Rectangular volume | V = L × W × H | Boxes, trays, tanks, sheets, and blocks |
| Cylinder volume | V = πr²h | Round containers and solid rods |
| Tube volume | V = (π/4)(OD² − ID²)L | Hollow pipes and tubing |
| Sphere volume | V = (4/3)πr³ | Spherical solid objects |
| Material mass | m = V × ρ | Converts object volume and density into weight |
| US fluid ounces | fl oz = mm³ ÷ 29,573.5295625 | Converts cubic millimeters to US fluid ounces |
| Weight ounces | oz = grams ÷ 28.349523125 | Converts grams to avoirdupois ounces |
Example data
| Mode | Example input | Approximate result |
|---|---|---|
| Rectangular liquid | 200 mm × 100 mm × 25 mm | 16.91 US fl oz |
| Vertical cylinder | 100 mm diameter, 25 mm depth | 6.64 US fl oz |
| Steel block | 100 mm × 50 mm × 5 mm | 6.92 oz |
| Aluminum cylinder | 25 mm diameter × 100 mm length | 4.68 oz |
| Copper foil | 0.035 mm thickness | About 1 oz/ft² |
Frequently asked questions
Can millimeters be converted directly to ounces?
No. Millimeters measure length, while ounces measure mass or fluid volume. Additional dimensions, geometry, or density are required.
What is the difference between ounces and fluid ounces?
An ounce measures mass. A fluid ounce measures volume. They are different units and cannot be used interchangeably.
Does the calculator support US and UK fluid ounces?
Yes. It calculates both standards and lets you choose which one appears as the primary result.
What density should I use for a custom material?
Use a trusted manufacturer specification or measured density. Select the matching density unit before calculating.
What is a troy ounce?
A troy ounce equals approximately 31.1034768 grams. It is commonly used for precious metals.
Can the calculator handle inches and feet?
Yes. Dimension selectors include millimeters, centimeters, meters, inches, and feet where appropriate.
How is a partly filled horizontal cylinder calculated?
The calculator uses the circular-segment area created by the liquid depth, then multiplies it by cylinder length.
Why does copper have theoretical and nominal results?
The theoretical value uses density and geometry. The nominal PCB value uses the common industry approximation of 34.8 micrometers per ounce.
Can I calculate the weight of tubing?
Yes. Enter outer diameter, inner diameter, length, and material density. The calculator subtracts the hollow core volume.
How does decimal precision affect the answer?
Precision changes displayed rounding only. Internal calculations retain full floating-point precision.
Can I export my calculation?
Yes. Use CSV for spreadsheet data or use PDF and Print to save a printable result.