Comparison

Decay calc vs Rail Model Calc

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

Head to head
About

Decay calc

This tool calculates the decay of radioactive isotopes over time, considering half-life for accurate activity predictions. It's useful in nuclear medicine, environmental monitoring, and radiation safety for handling and disposal of materials.

Highlights
  • Radioactive isotope decay calculation
  • Half-life integration
  • Activity prediction
  • Decay constant determination
  • Radiation dose calculation
Features
Read full description

Decay calc is a tool used to calculate the decay of radioactive isotopes over time. It takes into account the half-life of the isotope and allows for accurate predictions of the remaining activity of the isotope at any given time. Decay calc can be used in a variety of fields, such as nuclear medicine, environmental monitoring, and radiation safety. It can help determine the appropriate handling and disposal of radioactive materials and ensure the safety of individuals who may come into contact with them. In addition to calculating the remaining activity of the isotope, decay calc can also be used to determine the decay constant, which is a measure of the rate at which the isotope decays. This information can be used to calculate the radiation dose received by individuals who are exposed to the isotope. Overall, decay calc is a useful tool for anyone working with radioactive materials or interested in learning more about radioactivity and its effects. It provides accurate and reliable calculations that can help ensure safety and proper handling of radioactive materials.

About

Rail Model Calc

Features
Read full description

Overview This is a calculator app that includes calculation functions necessary when playing with railroad model. How to use After launching the app,the first screen that appears is the Home screen, which also serves as a menu. Swipe and tap the menu on the Home screen to transition to various calculation modes. You can use various calculation modes to perform calculations necessary for railway model track length and railway model production. This App offer the following calculation modes. •Home mode Home is available simple calculations. Set F1-F10 memory on this screen. •Normal mode It is a normal calculator. •Straight mode This mode calculates horizontal and vertical lengths when laying a straight rail diagonally. •Curve mode This mode calculates the vertical, horizontal, and diagonal lengths when laying a curve rail. •S-Curve mode This mode calculates the vertical, horizontal, and diagonal lengths when laying a s-curve rail. •Scale X/Y mode This mode calculates the scale. •Inch to MM mode This mode converts yards and inches to millimeters. For details on how to use it, there is a manual on "?" button. Disclaimer This calculator is for the railroad modeling hobby. The calculation results is the numerical value which be calculated by the developer. It may be different from the numerical value by model manufacturer. In particular, commercially available railroad model rails allow for dimensional errors. Therefore, the calculation results do not necessarily represent what the track layout cannot or can be done. This application is subject to change without notice. The developer assumes no responsibility for any loss or claims by third parties which may arise from the use of this application.

Screenshots

Decay calc3 screens
Rail Model Calc4 screens

Verdict

The call

The clearest difference is in-app purchases: Rail Model Calc at none against Decay calc's 1. Decay calc's advantage is ads (none vs shown) and update cadence (every 3 months vs every 14 months). On price, device support and iOS requirement 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. Decay calc sells 1 one-off in-app purchase. Rail Model Calc asks for nothing beyond the download.

UpkeepUpdate frequency

Decay calc ships an update every 3 months, Rail Model Calc every 14 months. The most recent releases landed on October 8, 2026 and October 1, 2026 respectively.

Scorecard3 real differences · 7 level
Decay calc versus Rail Model Calc: the parameters behind the verdict, then further details
ParameterDecay calcRail Model Calc
PriceFreeFree
Rating1.0 (1 ratings) — better—
Positive reviews50.0% of reviews—
Number of ratings1 — better—
Update frequencyEvery 3 months — betterEvery 14 months
AdsNo — betterYes
In-app purchasesYesNo — better
MonetizationFree with in-app purchases—
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.2 — better15.4
Further details — not scored
Size27 MB13 MB
Age rating17+4+
DeveloperAlexey BaranovNobuyuki Kumakura

In-app purchases

1 purchases

Decay calc

One-time1
  • Radio calc$0.99
None

Rail Model Calc

No in-app purchases

Questions

Is Decay calc free?
Decay calc is free to download, with in-app purchases available.
Is Rail Model Calc free?
Rail Model Calc is free to download, with no in-app purchases.
Do Decay calc or Rail Model Calc have ads?
Rail Model Calc shows ads; Decay calc does not.
Which is updated more often, Decay calc or Rail Model Calc?
Decay calc ships an update every 3 months, and Rail Model Calc every 14 months. Most recently, Decay calc was updated on October 8, 2026 and Rail Model Calc on October 1, 2026.

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