Millimeter - Screen ruler & measurements

Millimeter is a straightforward, complimentary screen ruler application. It allows you to measure small items that can fit within the device's display. The app features NO advertisements, ensuring an optimal experience and genuine full-screen measurements.

☛ ANY DEVICE can be calibrated for precise measurements in Calibration Mode, utilizing common standard objects (such as coins and credit cards) as reference points.

You have the option to personalize your app by purchasing additional features or modes.

📏 Here’s what you can do in the free version of the on-screen ruler:

- Calibrate Millimeter using custom or standard items

- Access Ruler Mode to measure in both metric and imperial units: mm and inches

- Utilize an extra vertical ruler for 2D measurements (📐)

- Measure area for 2D shapes (⬛)

- Determine the width/height ratio of rectangular items in 2D

- Lock or unlock rulers in any mode to enhance usability (🔒)

- Use a fine grid (1mm for millimeter measurements) 👍

- Incorporate fractions for inch measurements

- Read an interactive Help / Guide detailing all available features in each mode

- Employ the app as a conventional ruler

- Engage full-screen mode to improve user experience in Ruler mode

💳 You can enhance your free version and acquire additional modules and features, which provide the following functionalities:

- Spirit / bubble level for assessing incline or tilt angle 🔮

- Parts Mode to divide length or objects into equal segments

- Thread per inch (TPI) measurement pattern (🔩) in Parts mode

- Circle Mode for measuring circular objects (🔴)

- Divide circles into equal sectors or angles

- Protractor / Goniometer Mode to measure angles (⚪)

- Manually set exact size, length, diameter, or number of parts through keyboard input (⌨)

- Switch background to BW night mode for power conservation (🔋) and enhanced visibility (🌓)

Utilize this screen ruler for various purposes to measure small items that can fit the screen of your phone or tablet: jewelry, gems, rings 💍, stones, screws, bolts, button diameters, nuts, knitting needles, knitting patterns, washers, insects, mosaic tiles, hooks, thread, frame wrap angles, etc.

Measurement Units: millimeters (mm), inches (in). Fractions are supported for inch measurements.

Supported languages include:

- English, German, Russian, Japanese, and French.

📖 More about the app can be found through the provided link.

The VisTech.Projects Team.

Precision in Your Palm: How Millimeter Became My Indispensable Digital Caliper

As someone who constantly measures components for model-building and jewelry repairs, Millimeter transformed my smartphone into a shockingly reliable metrology lab. The initial calibration using a Canadian quarter felt almost magical – aligning the on-screen ruler with the coin's exact 23.88mm diameter created a reference standard that remained consistent across weeks of use. 

Where Millimeter truly shines is in its layered measurement modes. Measuring a vintage watch gear involved: first determining its 1.8mm thickness in Ruler Mode (with 1mm grid enabled), then switching to Circle Mode to confirm the 5.3mm bore diameter, and finally using Parts Mode to verify 32 perfectly spaced teeth – all without reaching for physical tools. The fractional inch display proved invaluable when restoring an antique frame; seeing 5/16" instead of 0.3125" eliminated calculation errors during wood trimming. 

During a camping trip, the bubble level module (a paid feature) saved my astrophotography rig setup on uneven terrain. This app transcends utility – it delivers the profound satisfaction of absolute dimensional certainty.

Frequently Asked Questions:

Q: How accurate is calibration using coins/cards?

A: Remarkably precise when done carefully. Using a verified USD quarter (24.26mm) as reference, subsequent measurements of known objects (e.g., SD card - 24mm) showed ≤0.2mm variance. Accuracy depends on:

Using undamaged reference objects

Calibrating in bright, shadow-free light

Zooming to 200% during calibration alignment

Q: Are paid features like Circle Mode worth it?

A: Essential for technical work. Circle Mode calculates diameters from arcs (perfect for partial gears). Parts Mode's TPI gauge helped me identify M4-0.7 threads instantly. Protractor Mode measured dovetail angles in woodworking. Power users will recoup costs in saved time.

Q: Can it measure objects larger than my screen?

A: Indirectly yes. Use the "Keyboard Input" paid feature: Measure a 10mm segment of a long item, input this partial length, then physically slide the item while the app accumulates total length mathematically. Works for straight objects up to ~2m.

Q: How does it handle screen protectors/thickness?

A: Calibration accounts for this. Place reference object on the protector during calibration. The app calculates parallax compensation, making measurements surface-accurate regardless of glass thickness.

Q: Is fractional inch mode practical for precision work?

A: Surprisingly so. It displays down to 1/64" (0.396mm), with optional 1/128" in settings. Ideal for imperial machining plans or vintage restoration where fractional specs are mandatory.

Q: Does night mode affect measurement accuracy?

A: No – BW night mode only inverts colors for visibility. Measurement algorithms remain unchanged. Critical for low-light workshops where screen glare compromises traditional calipers.

Q: Can I trust it for jewelry appraisals?

A: For gem dimensions (e.g., princess cut 5.5x5.5mm), yes. But it cannot replace gemological tools for carat weight/clarity. Perfect for verifying setting sizes or chain links pre-purchase.