Several tools can measure roof slope — each with different cost, accuracy, and convenience trade-offs. The collective category goes by several names: a roof slope measuring tool (the descriptive trade phrasing), a pitch gauge (the most-common shop name for any device that reads roof pitch directly), a roof slope gauge (alternate phrasing for the same device), or a pitch slope locator (used in some specialty trade catalogs). Software versions are commonly called a pitch gauge app, roof pitch app, free roof pitch app, roof pitch finder app, or roof slope app — same function, different platform.
This guide compares the four most common categories: a 2-foot spirit level with a tape (the classic manual approach), a digital angle finder or pitch gauge with degree readout, a smart level (electronic level with full slope display), and a smartphone clinometer app or roof pitch app. Each option has its place; the right choice depends on how often you measure pitch and how much accuracy your project actually needs.
Spirit level + tape ($25–50)
The classic combination. A 2-foot bubble level and a 25-foot tape, used together to measure rise per 12 inches of run. Accurate to about 0.5° on a clean roof or rafter.
Pros: cheapest, most reliable, no batteries. Cons: requires manual math (rise per 12 → degree conversion), reading is sensitive to where you place the level.
Digital angle finder ($25–80)
A small electronic device with a built-in accelerometer that reads angle directly in degrees. Some models have magnetic bases to stick to ferrous metal. Accurate to 0.1° on a calibrated unit.
Pros: instant degree readout, no math required, easy to use one-handed. Cons: needs occasional calibration, batteries can die at the worst moment.
Smart level / electronic level ($50–150)
A spirit level with a digital readout, often combining a traditional bubble vial with an electronic angle display. Useful for both pitch measurement and for general framing layout.
Pros: works as both a standard level and an angle finder, longer battery life than dedicated angle finders, more rugged. Cons: more expensive, larger to carry around.
Smartphone clinometer app (free–$5)
iOS Measure (built-in) or Android equivalents use the phone's accelerometer to read tilt. Accuracy is typically ±1° on a calibrated phone, less on a phone with drift.
The mobile sensor mode in the calculator on this site uses the same principle and is the easiest way to capture an angle and get the equivalent pitch in one step.
Pros: free, always with you, integrates with the calculator on this site. Cons: less accurate than dedicated tools, sensitive to phone case thickness and orientation.
| Tool | Cost | Accuracy | Pros | Cons |
|---|---|---|---|---|
| Spirit level + tape (manual) | $25 - $50 | ±0.5° | Cheap, reliable, no batteries | Manual math; placement-sensitive |
| Digital angle finder | $25 - $80 | ±0.1° | Instant degree readout; one-handed | Battery-dependent; needs occasional calibration |
| Smart level (digital level) | $50 - $150 | ±0.1° | Works as level + angle finder; rugged | More expensive; bulkier to carry |
| Smartphone clinometer app | Free - $5 | ±1° | Always with you; integrates with web calculator | Less accurate; case interference; phone drift |
| Pitch hopper + visual estimate | $80 - $200 | ±0.5/12 (~2°) | Direct rise/run readout | Specialty roofing tool only |
| Aerial measurement service (EagleView, Hover) | $25 - $100 per home | ±1° | No roof access; complete roof report | Cost per use; 1-3 day turnaround |
Need to run the numbers?Use the free roof pitch calculator on the home page to convert pitch to angle, calculate rafter length, or estimate roof area in any unit.