Free Online Measurement Tools & Calculators
Choose a tool, enter what you know, and get a clear result. No account, download or complicated setup needed.
Length Unit Converter
Type any length to see it in all four units at once.
Conversion rule: 1 inch = exactly 25.4 mm; 1 foot = exactly 12 inches. Displayed decimals are rounded.
Circle Size Calculator
Enter a radius, diameter, circumference or area to find the other measurements.
For a perfect circle: diameter = 2 × radius, circumference = π × diameter, and area = π × radius². For area input, select the corresponding square unit.
Will It Fit? Clearance Checker
Compare the outside size of an item with a space's usable inside dimensions.
Checks all six 90° box orientations. Clearance is required on BOTH sides of each dimension. It does not simulate the path through a doorway, hinges, curved openings or diagonal insertion.
Printable 150 mm Ruler
Print a metric guide with millimeter marks, then check its size before use.
Beverage Can Format Comparison
Explore typical can sizes side by side, including approximate outer height and diameter.
Illustrative format dimensions, not verified specifications for a specific brand or supplier. Capacity is nominal fill volume, not calculated exterior volume. Check your actual can or a current supplier drawing before designing packaging.
How to Use the Measurement Tools
Start by choosing the calculator that matches your question. Each tool gives results as you enter a number—there is no need to sign up. Use the built-in examples if you want to see how a tool behaves before entering your own measurements.
Convert a Length
Choose centimeters, millimeters, inches or feet. Enter one value and read the equivalent lengths in all four units. Use Copy conversions when you need the results for notes or a project.
Work Out Circle Measurements
Select the measurement you already know, then type its value. The calculator derives the remaining dimensions and area. Use square units when entering an area.
Check Item Fit
Enter an item's outside height, width and depth. Then enter the inside usable space, choose a clearance allowance and review the result. A fit result is a planning check, not a physical guarantee.
Print a Metric Ruler
Choose Print ruler. Set printing scale to 100%, disable auto-fit, then measure the calibration line on paper. Never assume your screen's rendering is actual size.
Compare Can Formats
Select two common beverage-can formats to see estimated height, diameter and capacity differences. Use product documentation for exact branded container sizes.
Pick the Right Tool for Your Task
| You want to… | Use this tool | What you'll learn |
|---|---|---|
| Change a size into another unit | Length Unit Converter | Equivalent lengths in mm, cm, inches and feet |
| Work out a circle's circumference | Circle Size Calculator | Radius, diameter, circumference and area |
| See whether a box fits inside a shelf | Fit & Clearance Checker | Whether an axis-aligned orientation clears the space |
| Measure a small object on paper | Printable Ruler | A 150 mm metric reference after calibration |
| Compare common drink-container formats | Can Format Comparison | Typical height, diameter and capacity differences |
Before You Rely on a Measurement
Conversions use exact unit definitions, but displayed answers are rounded for legibility. Circle calculations assume a perfect circle. The fit checker assumes rigid rectangular bounding boxes and only 90-degree orientations. The printable ruler is reliable only when the print scale has been checked. Can dimensions are illustrative, and real packaging varies.
For cutting, fabrication, shipping, purchasing, construction or other precision work, remeasure the actual object and consult current manufacturer specifications. A calculation can be mathematically correct even when the input measurement is wrong.
Measurement Tool FAQs
Can I use the tools on my phone?
Yes. The calculators are designed to adapt to small screens. You can enter values and view results on mobile; use a printer and verify scale if you need a physical ruler.
Are the tools free, and is an account required?
Yes, the tools are free to use and no account is required. Calculations run in your browser.
Why do conversion results sometimes show decimal places?
Many unit conversions produce repeating or long decimal values. The tools show rounded results for readability, even though the underlying inch, foot and metric relationships are defined exactly.
Can I enter a circle's area instead of its diameter?
Yes. Select Area as your known measurement, choose the matching square unit, and enter a positive value. The calculator finds its radius, diameter and circumference.
Does a “fits” result mean I can definitely insert the item?
No. The result checks box dimensions in six 90-degree orientations. Doors, handles, corners, narrow entrances and movement during insertion may prevent the item from fitting in practice.
Why should I verify the printed ruler?
Printers and print dialogs may resize output. Measure the included 50 mm calibration line with a trusted physical ruler before using the printed marks.
Are the can dimensions exact for every brand?
No. The example formats are approximate and may differ by supplier, market and packaging design. Use a specific manufacturer's technical drawing for exact specifications.
Do I need internet access after the page loads?
The calculations themselves run in your browser without sending entered measurements to a calculation server. Loading the page and its files initially requires access to the website.