There isn’t a single “best” option—choose based on how you plan to use it.

• Inductive tach/hour meters: Wrap around the spark plug lead to read ignition pulses. Great for mowers, generators, and ATVs when you want continuous RPM plus hours, service reminders, or even temperature.
• Non-contact laser/photo tachometers: Aim at reflective tape on a pulley or flywheel for quick spot checks without wiring. Handy for bench testing and rotating parts.
• Compatibility: Look for settings for 2‑stroke and 4‑stroke engines and a suitable RPM range (chainsaws may need higher ranges).
• Durability & power: Water-resistant designs and replaceable batteries can be helpful outdoors.

On Walmart.com, check product specs and customer Q&As to match features to your engine and use case.

You can measure RPM two common ways—inductive or non-contact.

1. Inductive tachometer:
   • With the engine off, wrap the sensor lead around the spark plug wire (several turns) and secure it.
   • Set the tach for your engine type (2‑stroke or 4‑stroke, as applicable).
   • Start the mower and read RPM on the display. Adjust idle or throttle as needed.
2. Non-contact laser/photo tach:
   • Place a small strip of reflective tape on a rotating surface (like a pulley).
   • Aim the sensor at the tape from a safe distance and hold steady.
   • Read the RPM once the reading stabilizes.

Always keep hands and loose clothing away from moving parts. Lighting, signal quality, and setup can affect readings.

Some multimeters include an RPM or frequency (Hz) function. If yours supports it and you use an appropriate inductive pickup, it can estimate RPM from ignition pulses.

• Basic idea: Measure pulse frequency and convert to RPM using your engine’s pulses per revolution (RPM ≈ Hz × 60 ÷ pulses/rev).
• Engine specifics: Small engines differ—2‑strokes may spark every revolution, while 4‑strokes might spark every other revolution (or use a wasted-spark system). Settings matter.
• Limitations: High-voltage ignition leads are hazardous—don’t clip leads directly. Signal noise and engine type can affect accuracy.
• Simpler alternative: A dedicated small engine tachometer is typically easier to use for quick, consistent readings.

Consult your multimeter’s manual for safe connection methods and compatible accessories.

They can provide a rough estimate, but consistency varies by setup and environment.

• Microphone-based apps: Analyze engine sound to estimate RPM. They may work reasonably on steady-pitch engines (like generators), but background noise and exhaust tone can throw off results.
• Camera/strobe apps: Track a reflective marker on a rotating part. These can be useful with good lighting and moderate speeds.
• Limitations: Vibration, wind, distance, and lighting all affect accuracy. Keep your phone well away from moving parts.
• When precision matters: For maintenance and tuning, a dedicated tachometer tends to deliver more reliable readings.

Use apps as a quick check, and follow all safety precautions around rotating equipment.

Both are useful—pick based on whether you need ongoing monitoring or quick checks.

• Inductive tach/hour meter: Reads pulses from the spark plug wire for live RPM and typically logs total hours. Some include service reminders and temperature. Great for mowers, ATVs, and generators where the unit stays on the equipment.
• Non-contact laser/photo tach: Requires reflective tape and line of sight to a rotating surface. Ideal for spot checks on pulleys, shafts, or bench testing without wiring.
• Considerations: Inductive models suit spark-ignition engines; photo tachs can work when a spark lead isn’t accessible. Outdoor glare and distance can affect non-contact readings.

Review feature lists on Walmart.com to match the tool to your workflow.