Tested: the best inclinometer apps for measuring roof pitch, ramp slope, vehicle tilt, and drainage grade. Calibration, units, accuracy, and real-world results.
A bubble level answers one question: is this flat? An inclinometer answers a harder one:
If you work with slopes — roof pitch, drainage grades, wheelchair ramps, vehicle suspension alignment, solar panel angles, trail grades — you need numeric precision, not a green bubble. You need degrees, percent grade, or ratio readings. You need calibration you can trust. And increasingly, you need it on a device you already carry.
We tested inclinometer apps on tasks that demand real accuracy: measuring a 4/12 roof pitch from a rafter, verifying a 2% drainage slope on a patio, checking vehicle tilt on a lift, and confirming a hiking trail grade against posted signs. Here is what held up — and what did not.
| Capability | Basic Level App | Inclinometer App |
|---|---|---|
| Measures tilt angle | Visual only (bubble) | Numeric (° / % / mm-m / ratio) |
| Multiple axes | Usually one (horizontal) | Horizontal + vertical + free angle |
| Calibration | Zero-point or none | Multi-point (180° flip) with profiles |
| Accuracy potential | ±1–2° | ±0.1–0.3° (calibrated) |
| Tolerance / pass-fail | No | Configurable thresholds |
| Sensor diagnostics | No | Stability/confidence indicators |
| Use case | "Is this level?" | "What is the exact slope?" |
This is the inclinometer app that takes precision seriously without making you pay for it. It combines the simplicity of a bubble level with the accuracy of a dedicated inclinometer — all in one lightweight package.
Available on
The veteran inclinometer app. Its standout feature is camera-based slope measurement: overlay angle lines on the live camera view to measure the slope of a distant object (roof edge, hillside, ramp from afar).
Measuring slopes from a distance using the camera overlay — e.g., estimating roof pitch from the ground without climbing.
Basic calibration (no 180° flip or profiles). No tolerance guidance. No confidence indicator. Ads in the free version.
A multi-function outdoor measurement tool that combines inclinometer, compass, rangefinder, and GPS. Originally designed for forestry (measuring tree height and slope), it is popular with hikers, surveyors, and outdoor professionals.
Outdoor field work where you need slope + compass bearing + distance estimation in one app. Measuring trail grades, hillside angles, and tree heights.
Android only. Complex interface — overkill for simple slope measurements. Accuracy of distance estimation depends on GPS quality. Pro version required for full features.
Part of the Smart Tools suite (ruler, compass, protractor, noise meter). The clinometer shows numeric angles with a visual horizon line. Calibration is available.
Users who want multiple measurement tools in one app and are willing to pay for the Pro version to remove ads.
Ads in the free version. Requests more permissions than necessary (including location). Android only. No tolerance guidance. No confidence indicator.
The iPhone's built-in level in the Measure app shows degrees and lets you zero the reference point. For a built-in tool, it is decent — but it is a level, not a true inclinometer.
iPhone users doing quick level checks who do not want to install anything.
Single mode (surface level only). No angle gauge. No percent grade or ratio. No tolerance guidance. No measurement export. iPhone only.
| App | Inclinometer Mode | Calibration | Units | Tolerance | Confidence | Hold | Share | Ads | Price | Platforms |
|---|---|---|---|---|---|---|---|---|---|---|
| Yes (dedicated) | 180° + profiles | ° % mm/m ratio | OK/NEAR/OUT | Yes | Yes | Card | None | Free | Android, iOS | |
| Clinometer (Plaincode) | Yes + camera | Basic | ° | None | No | No | No | Free/Pro | Free/$1.99 | iOS, Android |
| Dioptra | Yes + compass | Yes | ° % | None | No | No | Photo | Free/Pro | Free/$3.99 | Android |
| Smart Tools Level | Basic | Yes | ° | None | No | Yes | No | Moderate | Free/$2.99 | Android |
| Apple Measure Level | No (level only) | Zero-point | ° | None | No | No | No | None | Free | iOS |
Place your phone on a rafter in the attic, or against the roof edge from a ladder. Read the angle in degrees or ratio. A standard residential roof is 4/12 to 9/12 (18.4° to 36.9°). Use the angle gauge mode with ratio units for direct pitch reading.
Patios, sidewalks, and driveways need a minimum slope for water drainage — typically 1–2% (0.6°–1.1°). Set your tolerance to 1% and get instant pass/fail as you check along the surface.
ADA requires max 1:12 slope (4.76° or 8.33%). Set tolerance to this threshold. Walk along the ramp with your phone flat against the surface. Green = compliant, red = too steep.
Check if a vehicle is sitting level side-to-side (roll) and front-to-back (pitch). Place phone on the roof or a flat chassis point. Useful for diagnosing suspension issues, leveling RVs and trailers, and setting up off-road vehicles.
Optimal solar panel tilt depends on your latitude. Set the target angle and verify each panel reads within tolerance. The hold function lets you place the phone on the panel, freeze the reading, and step back to document it.
Posted trail grades (e.g., "15% grade") can be verified with your phone. Useful for accessibility planning, fitness tracking accuracy, and outdoor education.
A well-calibrated phone app typically achieves ±0.1° to ±0.3° accuracy. A professional digital inclinometer (like Bosch GIM 60) achieves ±0.05°. For most practical purposes — construction, DIY, inspections — phone accuracy is sufficient. For laboratory or precision engineering, use a dedicated instrument.
They are essentially the same thing: a tool that measures the angle of a surface relative to gravity. "Inclinometer" and "clinometer" are interchangeable. "Tilt meter" usually refers to instruments that measure very small angles (used in geology and structural monitoring).
Yes. Percent grade = tan(angle) × 100. A 1° slope is approximately 1.75% grade. Most basic level apps only show degrees, but Bubble Level & Angle Gauge supports degrees, percent, mm/m, and ratio natively.
This is sensor offset — the accelerometer's zero point is not perfectly aligned with the phone's physical edge. This is normal and expected. 180° flip calibration specifically corrects this error by averaging the offset from both orientations.
A basic level app tells you "flat or not flat." An inclinometer app tells you exactly how much something is tilted and whether that tilt is within your acceptable range. For anyone who works with slopes — roofs, ramps, drainage, vehicles, solar panels, trails — the difference is between guessing and knowing.