Comparison

Roll Calculator vs Light Meter LM

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

Head to head
About

Roll Calculator

This app helps users calculate full and partial roll dimensions for various materials. It allows for inventory management, saving calculations, and defining custom material templates. Easily switch between Imperial and Metric units for precise measurements.

Highlights
  • Calculate full and partial roll dimensions
  • Manage inventory with 'My List'
  • Define custom material templates
  • Switch between Imperial and Metric units
  • Calculate material area coverage
  • Determine material length by counting wraps
Features
Read full description

Roll Calculator makes it easy to work with all materials and roll specifications — Regardless of industry! FEATURES - Easily calculate full and partial roll dimensions. - Manage inventory and save your calculations in My List. - Define Material Templates for any material and size. - Quickly switch between Imperial or Metric units. - Works with any rolled sheet material. Top 4 reasons to use Roll Calculator 1. You work with rolled material and often need to calculate how much material is left on the roll. 2. You are looking for a tool to help manage your partial roll inventory. 3. You often find yourself calculating the area a roll of material will cover. 4. You need to know the length of material left on a roll but forgot to write it down. Don’t panic, just count the number of wraps!.

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/

Screenshots

Roll Calculator4 screens
Light Meter LM4 screens

Verdict

The call

Roll Calculator and Light Meter LM both sit at 4.4 stars, but that hides the real split: 40% of Light Meter LM's written reviews are positive against 0% of Roll Calculator's. Light Meter LM also leads on ratings volume (2.6K vs 14). Roll Calculator's advantage is in-app purchases (none vs 3) and iOS requirement (12.0 vs 15.0). On price, rating, update cadence and ads 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. Roll Calculator asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

On the App Store both sit at effectively the same score — 4.4 for Roll Calculator against 4.5 for Light Meter LM. That said, the two scores are not equally well evidenced: Light Meter LM has 2.6K ratings behind it against 14, so its average is the more settled of the two. Written reviews are what separate them: 0% of Roll Calculator's written reviews are positive against 40% of Light Meter LM's.

UpkeepUpdate frequency

Roll Calculator ships an update fortnightly, Light Meter LM monthly. The most recent releases landed on October 24, 2026 and October 29, 2026 respectively.

Scorecard5 real differences · 5 level
Roll Calculator versus Light Meter LM: the parameters behind the verdict, then further details
ParameterRoll CalculatorLight Meter LM
PriceFreeFree
Rating4.4 (14 ratings)4.5 (2.6K ratings) — better
Positive reviews0.0% of reviews40.4% of reviews — better
Number of ratings142.6K — better
Update frequencyFortnightly — betterMonthly
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS12.0 — better15.0
Further details — not scored
Size9 MB22 MB
Age rating4+4+
DeveloperBeta Flash Solutions Inc.Lightray Innovation GmbH

Customer experience

Roll Calculator

All ratings11 ratings
Positive81.8%
Neutral0.0%
Negative18.2%
Written reviews1 reviews
Positive0.0%
Neutral100.0%
Negative0.0%

Light Meter LM

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

Bugs and requests

Roll Calculator

Not enough reviews yet to summarise bugs or 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

In-app purchases

None

Roll Calculator

No in-app purchases

3 purchases

Light Meter LM

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

Questions

Is Roll Calculator free?
Roll Calculator is free to download, with no in-app purchases.
Is Light Meter LM free?
Light Meter LM is free to download, with in-app purchases available.
Which has better reviews, Roll Calculator or Light Meter LM?
Light Meter LM is rated higher. Roll Calculator averages 4.4 out of 5 from 14 ratings, while Light Meter LM averages 4.5 from 2.6K ratings.
Do Roll Calculator or Light Meter LM have ads?
Neither Roll Calculator nor Light Meter LM shows ads.
Which is updated more often, Roll Calculator or Light Meter LM?
Roll Calculator ships an update fortnightly, and Light Meter LM monthly. Most recently, Roll Calculator was updated on October 24, 2026 and Light Meter LM on October 29, 2026.

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