Comparison

RuinRisk vs FX LotSize

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

Head to head
About

RuinRisk

Visualize your investment and trading risk with this intuitive calculator. Easily adjust parameters like risk per trade and win rate to understand your probability of ruin. Offers both basic and advanced analysis modes for beginners and experienced traders.

Highlights
  • Probability of Ruin Simulation
  • Heatmap Risk Visualization
  • Monte Carlo Simulations (Pro Mode)
  • Maximum Drawdown Estimation (Pro Mode)
  • Drawdown Probability Analysis (Pro Mode)
  • Strategy Comparison
Features
Read full description

RuinRisk shows how likely a trading plan is to wipe out your capital, and how deep the drawdowns along the way can get. Enter three numbers and the result updates as you move the sliders. THREE INPUTS • Win rate • Risk:reward ratio • Capital risk (the share of your capital you risk on each trade) Set each one with a slider or type the value directly. All three move in steps of 0.1 and are remembered the next time you open the app. FREE: LEGACY MODE • CALC: Risk of ruin, defined as the probability of losing all of your capital, calculated instantly from your three inputs. • HEATMAP: A color-coded risk-of-ruin table. Choose which parameter to hold fixed, pinch to zoom, and double-tap to return to the default zoom. • A short walkthrough appears on first launch and can be reopened anytime from the button at the top right. PREMIUM: PRO MODE Pro mode is unlocked with a one-time in-app purchase. It is not a subscription. • CALC: Ruin is defined as your capital falling to a level you choose (50% by default; 30% and 20% are also available). The theoretical value is shown next to a log-growth estimate, along with the difference between the two. • HEATMAP: Marks your current settings on the map, compares which of the three inputs drives your risk the most, and shows how far the risk of ruin would fall if you changed one input on its own. • ANALYSIS: Monte Carlo simulation of maximum drawdown over 100, 500 or 1,000 trades, with the probability of a 10%, 20%, 30%, 50% or 70% drop from the peak. Results are summarized from three perspectives: ruin probability, Monte Carlo drawdown, and position sizing against the Kelly criterion. • MATRIX: A table of drawdown probabilities from 5% to 100% across 100, 500 and 1,000 trades. Save up to five plans, compare them side by side, apply a saved plan to your inputs, and export the table as a CSV file. • Settings: Ruin definition, compounding on or off, simulation quality (1,000, 10,000 or 100,000 runs), and the percentile used for maximum drawdown (50th, 75th or 95th). Legacy and Pro define ruin differently, so the same inputs give different numbers in each mode. The app explains the difference on screen. WHO IT'S FOR • Traders who want to check a position size before putting real money at risk • Anyone comparing approaches with different win rates and risk:reward ratios • People learning money management who want to see how the numbers move GOOD TO KNOW • No ads, no account and no tracking. Your inputs and saved plans stay on your device. • Supports VoiceOver and larger text sizes. • For iPhone and iPad. Requires iOS 18 or later. • Available in English and Japanese. RuinRisk is a calculation tool for education and reference. Its results are theoretical values and simulations based on the numbers you enter. They are not investment advice, and they do not predict or guarantee future results. Trading involves the risk of loss.

About

FX LotSize

Features
Read full description

How to use the app Lot calculation tool You can calculate the appropriate lot when entering FX (holding a position). 1. Set the currency pair 2. Enter the margin (account balance) 3. Set the loss tolerance as a percentage of the margin 4. Finally, enter the stop loss 5. Tap the calculate button to display the appropriate lot. Profit and loss ratio tool 1. Set the profit lock pips (take profit) 2. Set the loss tolerance pips (stop loss) 3. Automatically display risk reward Settings Regarding the currency of 1 lot, please check the information of your trading company and set it. The default is set to 10,000 currency per lot. The loss tolerance (%) can be changed to the % set when the app is launched. The currency pair at launch can be changed to the currency pair set when the app is launched. The currency pair list can be listed as you like. The only currency pairs available in the free version are USD/JPY and EUR/USD/GBP/JPY. If you want to calculate lots for other currency pairs, you will need to upgrade. After upgrading, you will be able to use all currency pairs without any charge.

Screenshots

RuinRisk4 screens
FX LotSize4 screens

Verdict

The call

The clearest difference is update cadence: FX LotSize at every 3 days against RuinRisk's every 3 months. On price, ads, in-app purchases and device support 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. RuinRisk sells 1 one-off in-app purchase and FX LotSize sells 1 one-off in-app purchase. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

RuinRisk ships an update every 3 months, FX LotSize every 3 days. The most recent releases landed on November 1, 2026 and October 22, 2026 respectively.

Scorecard1 real difference · 9 level
RuinRisk versus FX LotSize: the parameters behind the verdict, then further details
ParameterRuinRiskFX LotSize
PriceFreeFree
Rating4.0 (1 ratings) — better—
Positive reviews80.0% of reviews—
Number of ratings1 — better—
Update frequencyEvery 3 monthsEvery 3 days — better
AdsNoNo
In-app purchasesYesYes
MonetizationPaid—
DevicesiPhone, iPad — betteriPhone
Requires iOS18.018.0
Further details — not scored
Size2 MB8 MB
Age rating4+4+
DeveloperRYUICHIROU SHIMONOyuki kawahito

In-app purchases

1 purchases

RuinRisk

One-time1
  • RuinRisk Premium$2.99
1 purchases

FX LotSize

One-time1
  • All Currency Pair$5.99

Questions

Is RuinRisk free?
RuinRisk is free to download, with in-app purchases available.
Is FX LotSize free?
FX LotSize is free to download, with in-app purchases available.
Do RuinRisk or FX LotSize have ads?
Neither RuinRisk nor FX LotSize shows ads.
Which is updated more often, RuinRisk or FX LotSize?
RuinRisk ships an update every 3 months, and FX LotSize every 3 days. Most recently, RuinRisk was updated on November 1, 2026 and FX LotSize on October 22, 2026.

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