Comparison

Light Meter LM vs Random Alarms

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Light Meter LM

Transform your smartphone into a professional light meter. Measure illuminance and color temperature with scientifically validated accuracy, trusted by professionals. Requires a simple diffuser for precise readings.

Highlights
  • Measure illuminance (lux/foot-candle)
  • Measure color temperature (Kelvin)
  • Industry-leading accuracy
  • Pre-calibrated for your device
  • Low light sensitivity
  • Save peak reading
  • Custom calibration option
Read full description

Turn your smartphone into a professional-grade light meter. Measure illuminance (lux/foot-candle) and color temperature (CCT in Kelvin) with unmatched accuracy — trusted by photographers, engineers, and lighting professionals worldwide. Why waste money on a hardware meter when you’re already carrying one in your pocket? The LM-3000 offers the same quality and usability as a traditional hardware light meter. Developed by optics scientists at the Zurich University of Applied Sciences, LM-3000 is the only light meter app scientifically validated for accuracy. It achieves professional-grade precision by leveraging your iPhone's front-facing camera sensor with advanced RAW image processing. Unlike relying on estimates like other apps, it adheres to the ISO/CIE 19476 standard, ensuring measurements you can trust for critical applications. MEASUREMENTS ⎷ Illuminance in lux or foot-candles ⎷ Correlated color temperature in kelvin FEATURES ⎷ Industry-leading accuracy, matching professional high-end lux meters ⎷ Pre-calibrated for your specific device ⎷ Excellent low light sensitivity to detect light pollution ⎷ No ads ⎷ No Bluetooth and location permission required ⎷ In-app manual ⎷ Save peak reading ⎷ HOLD function with acoustic signal ⎷ Custom calibration option to align readings to another meter DIFFUSER REQUIRED Like every real light meter, the LM-3000 requires a diffuser to measure accurately. A diffuser scatters incoming light evenly on the sensor and prevents hotspots. While it may sound complex, the solution is surprisingly easy. You have two options: 1) Easily build a diffuser yourself in less than a minute using standard printer paper. This is accurate enough for most use cases. 2) Get the dedicated Diffuser Accessory (free worldwide shipping) for best accuracy and convenience. More details on https://lightray.io/diffuser/ (!) Avoid apps that don’t require a diffuser! They are inaccurate because they ignore the basic physics of light measurement. TRY BEFORE YOU BUY The LM-3000 is free to download and comes with a free trial period. The trial period lasts for two non-consecutive days, giving you enough time to see if the app fits your needs. The status of your free trial will be shown as the "battery level" on the top right of the LM-3000's display and on the "Battery Status" screen. Once your light meter's "battery" is depleted, you may choose a Charging Option to keep using the app. You can pick what works best for you: → Single Charge — top-up for another 48 hours (perfect for occasional use), → Continuous Charging — a monthly subscription (great if you use it regularly), → Unlimited Battery — a one-time purchase for unlimited lifetime access LM-3000 is the result of over five years of dedicated research and development, ensuring you get a tool that is precise and reliable. Every in-app purchase supports future development and helps keep the app ad-free for everyone. As a member of 1% for the Planet, we donate at least one percent of all revenue to environmental non-profits — this is our way of giving back. ACCURACY Accuracy is not an afterthought — Apps developed by Lightray Innovation are developed according to the ISO/CIE 19476 standard. Thanks to RAW image processing and a default calibration per device model they’re able to match the performance of high quality traditional hardware light meters. To ensure quality we rigorously test our apps regularly on upcoming devices. DOWNLOAD FOR FREE. TRUSTED BY MILLIONS. LM-3000 is the go-to light meter for photographers, professionals, engineers, and lighting enthusiasts who rely on accurate measurements — not estimates or guesswork. Download for free today and experience the difference! See the app in action: https://youtu.be/EJW7NfE2qCk Terms and Conditions: https://lightray.io/lightmeter/terms/

About

Random Alarms

Receive occasional reminders without being tied to a specific time. This utility app provides flexible notifications for when you need them, offering a less rigid approach to staying on track.

Highlights
  • Time-independent reminders
  • Occasional notification prompts
  • Flexible scheduling
  • User-controlled notifications
Features
Read full description

Maybe you want some occasional reminders... but without being restricted by fixed times?

Screenshots

Light Meter LM4 screens
Random Alarms4 screens

Verdict

The call

The clearest difference is review sentiment: Random Alarms at 100% against Light Meter LM's 40%. Random Alarms also leads on rating (5.0 vs 4.5). Light Meter LM's advantage is ratings volume (2.6K vs 1) and update cadence (monthly vs every 2 months). On price, ads, in-app purchases and monetization model there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Light Meter LM sells 3 in-app purchases, starting at $3.49 per month and Random Alarms sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

ReceptionRating · Positive reviews · Number of ratings

Random Alarms holds the better App Store score, 5.0 against 4.5. That said, the two scores are not equally well evidenced: Light Meter LM has 2.6K ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 40% of Light Meter LM's written reviews are positive against 100% of Random Alarms's.

UpkeepUpdate frequency

Light Meter LM ships an update monthly, Random Alarms every 2 months. The most recent releases landed on November 3, 2026 and November 4, 2026 respectively.

Scorecard5 real differences · 5 level
Light Meter LM versus Random Alarms: the parameters behind the verdict, then further details
ParameterLight Meter LMRandom Alarms
PriceFreeFree
Rating4.5 (2.6K ratings)5.0 (1 ratings) — better
Positive reviews40.4% of reviews100.0% of reviews — better
Number of ratings2.6K — better1
Update frequencyMonthly — betterEvery 2 months
AdsNoNo
In-app purchasesYesYes
MonetizationFree with in-app purchasesFree with in-app purchases
DevicesiPhone, iPad, iPod — betteriPhone, iPad
Requires iOS15.0 — better17.2
Further details — not scored
Size22 MB225 MB
Age rating4+12+
DeveloperLightray Innovation GmbHWuhan Jingyao Technology Co., Ltd.

Customer experience

Light Meter LM

All ratings2,595 ratings
Positive87.8%
Neutral3.7%
Negative8.4%
Written reviews208 reviews
Positive40.4%
Neutral6.3%
Negative53.4%

Random Alarms

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Bugs and requests

Light Meter LM

Reported bugs

3 issues
  • Diffuser not recognized even when used
  • App locks up/crashes
  • Constant diffuser pop-up interruptions

Requested features

3 requests
  • Ability to use rear camera
  • More flexible diffuser options
  • Improved accuracy without diffuser

Random Alarms

Not enough reviews yet to summarise bugs or requests.

In-app purchases

3 purchases

Light Meter LM

Subscriptions1
  • Continuous Charging$3.491 Month
One-time2
  • Single Charge$0.99
  • Unlimited Battery$19.99
1 purchases

Random Alarms

One-time1
  • Custom Audio Upload$0.99

Questions

Is Light Meter LM free?
Light Meter LM is free to download, with in-app purchases available.
Is Random Alarms free?
Random Alarms is free to download, with in-app purchases available.
Which has better reviews, Light Meter LM or Random Alarms?
Random Alarms is rated higher. Light Meter LM averages 4.5 out of 5 from 2.6K ratings, while Random Alarms averages 5.0 from 1 ratings.
Do Light Meter LM or Random Alarms have ads?
Neither Light Meter LM nor Random Alarms shows ads.
Which is updated more often, Light Meter LM or Random Alarms?
Light Meter LM ships an update monthly, and Random Alarms every 2 months. Most recently, Light Meter LM was updated on November 3, 2026 and Random Alarms on November 4, 2026.

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