--- schema_type: "SoftwareApplication" entity_type: "Mobile Application" app_name: "Time Duration/Add Calculator" developer_entity: "Kouji Yamauchi" bundle_id: "com.kouji1981.time" app_store_id: "1521417824" category: "Utilities" primary_platform: "ios" primary_monetization: "Free" offline_capable: false market_region: "US" platforms: "iOS & Android" app_last_updated: "2024-02-15" report_date: "2026-05-25" last_verified: "2026-05-25T18:55:47.580Z" report_version: "1.5" total_reviews: 0 confidence: "low" confidence_score: 0.35 data_age_days: 53 momentum_velocity: "zombie" intelligence_version: 3 competitor_count: 5 tags: ["utilities", "free", "mobile app", "app review", "app analysis", "users", "requiring", "quick,"] canonical_url: "https://marlvel.ai/apps/time-duration-add-calculator" license: "CC-BY-NC 4.0" content_version: "v2" --- # Time Duration/Add Calculator App Audit ## TL;DR {#tldr} - **Category**: Utilities · Free > **TL;DR:** Time Duration/Add Calculator is a utilities app by Kouji Yamauchi, available on iOS & Android. > > **Marlvel.ai App Intelligence** — Independent analysis. US Market. No publisher influence. > **Key Insight:** Time Duration/Add Calculator is a utilities app by Kouji Yamauchi. ## Quick Facts | Fact | Value | | :--- | :--- | | **Category** | Utilities | | **Developer** | Kouji Yamauchi | | **Pricing** | Free | | **Platforms** | iOS & Android | | **Confidence** | Low (0.35/1.0) | | **Data Age** | 53d | ## Metadata & Market Performance - **Publisher:** Kouji Yamauchi - **Category:** Utilities - **Target Audience:** Users requiring quick, utility-based time arithmetic for scheduling or duration tracking. - **Platforms:** iOS & Android - **Version Audited:** 1.5 - **Audit Date:** 2026-05-25 - **Signal Count:** 2 reviews analyzed - **Confidence:** Low (0.35/1.0) - **App Store ID (iOS):** 1521417824 - **Bundle ID:** com.kouji1981.time - **Google Play ID:** com.kouji1981.time - **Performance Trend:** Declining - **Data Window:** Analysis based on signals collected up to 2026-05-25 ## Executive Snapshot **What it is:** Time Duration/Add Calculator is a free, ad-supported utility for calculating time intervals and date arithmetic on iOS and Android. **Why users hire it:** Users hire this app to solve specific scheduling or duration-tracking problems, but the lack of feature updates makes it a fragile choice compared to actively maintained rivals. ## App DNA (Features & Intent) - **[Standard] Elapsed Time Calculation:** Calculates duration between two specific timestamps or dates. - **[Standard] Time Addition and Subtraction:** Computes future or past timestamps by adding or subtracting durations. - **[Standard] Unit Conversion:** Converts time intervals into alternative units. ## Market Position {#market-position} The app lacks significant market presence, evidenced by a zero-rating count across both iOS and Android platforms. This absence of social proof makes it difficult to compete with rivals that have established large user bases. ## Monetization Strategy - **Model:** Free - **Tiers:** Free with ad support - **Analysis:** The app operates on a free, ad-supported model with no in-app purchases. ## SWOT Analysis {#swot} **Core Strengths:** - Ad-supported model removes the entry barrier for casual users. **Critical Frictions:** - Zero-rating profile across both platforms signals low user engagement. - No updates since early 2024 on iOS and 2023 on Android. - Lack of wearable or cross-platform sync features. **Growth Levers:** - Integration of history logs to improve user retention. - Addition of multi-time zone support to match direct rivals. **Market Threats:** - High-velocity competitors like Dash Calc erode market share through frequent updates. - Lack of social proof compared to rivals with 78,000+ ratings. ## Recent Changes (v2 → v3) {#recent-changes} The app's competitive position has declined due to prolonged development stagnation, prompting a pivot in strategy toward feature parity with active, high-velocity rivals. **Overall trend**: Declining **Compared at**: 2026-05-25 ### High-impact changes - **[Shifted] Outlook Trend** (positioning) — Outlook trend moved from stable to declining, citing the lack of updates since 2023 as a primary driver for user loss. - **[Shifted] Competitive Landscape** (positioning) — Replaced legacy incumbents with active, high-velocity competitors like Dash Calc, Age Calculator, and CalcFast. ### Medium-impact changes - **[Added] Competitive Threats** (swot) — Added specific threats from high-velocity competitors like Dash Calc and the disadvantage of having zero ratings against rivals with 78,000+ ratings. - **[Added] Feature Gaps** (features) — Identified specific gaps in multi-time zone support, history logs, and wearable integration compared to active market alternatives. ## What's New - **Latest (v1.3, 3 years ago):** General bug fixes. ## App Momentum (Zombie) {#momentum} - No feature updates in 12 months. - Stagnant release cadence since 2023. > **Cadence:** 2 total versions · 0 majors in last 6 months · 830 days since last update · 387 days avg between updates ## The "So What?" (Strategic Takeaway) {#so-what} Time Duration/Add Calculator is an established utilities app that is completely free. > **Bottom Line:** The app provides basic utility but lacks the active development required to compete, so the PM should prioritize adding history logs to drive retention before the user base migrates to more frequently updated alternatives. **Best for:** Users requiring quick, utility-based time arithmetic for scheduling or duration tracking. ### PM Action Plan (Next Best Moves) - [ ] [INVEST] [HIGH IMPACT] Ship history logs because competitors use logs to increase session frequency → improve retention. — *Competitors like Time Duration Calculator use history logs to drive repeat usage.* _(trade-off: deprioritize Pause UI polish work — functional utility is the primary driver for this segment.)_ - [ ] [MAINTAIN] [MEDIUM IMPACT] Audit ad-placement frequency because ad-supported apps require high volume for revenue → stabilize user sentiment. — *The app relies on ads for revenue, requiring a balance between monetization and user experience.* _(trade-off: deprioritize No major lever displaced — audit is a low-resource maintenance task.)_ ### Feature Gaps vs Competitors - Multi-time zone support (available in Time Duration Calculator) - History log (available in Time Duration Calculator and CalcFast) - Apple Watch integration (available in CalcFast) ### Outlook: Declining The utility-calculator market is consolidating around apps that offer high-velocity updates and lifestyle integrations. Without a shift to active development, this app will continue to lose visibility to competitors that prioritize user engagement features. - 🔴 The lack of updates since 2023 on Android signals a shift to maintenance mode, which reduces the app's ability to retain users against active rivals. ## Key Metrics Summary | Metric | Value | | :--- | :--- | | Total Reviews | 0 | | Confidence | Low | | Pricing Model | Free | | Platforms | iOS & Android | | Key Features | 3 analyzed | | Trend | Declining | | Outlook | Declining | ## Competitor Comparison | App | Rating | Sentiment | Developer | | :--- | :--- | :--- | :--- | | **Time Duration/Add Calculator** (this app) | N/A/5 | N/A | Kouji Yamauchi | | [Dash Calc: Simple Fast Math](https://marlvel.ai/apps/dash-calc-simple-fast-math) | 5.0/5 | Thrilled | Enbright LLC | | [Age Calculator & Date of Birth](https://marlvel.ai/apps/age-calculator-date-of-birth-2) | 4.5/5 | N/A | ElQube Tech | | [Age Calculator – Date Counter](https://marlvel.ai/apps/age-calculator-date-counter) | N/A/5 | N/A | Mustafa Kulac | | [Time Duration Calculator](https://marlvel.ai/apps/time-duration-calculator) | 5.0/5 | Mixed | 俊华 罗 | | [CalcFast](https://marlvel.ai/apps/calcfast) | 4.2/5 | N/A | Hannes Sverrisson | ## Company Profile - **Developer:** Kouji Yamauchi - **Website:** [https://www.koutheend.com/](https://www.koutheend.com/) ## Data Sources & Links - **App Store:** [View on Apple Store](https://apps.apple.com/us/app/time-duration-add-calculator/id1521417824?uo=4) - **Google Play:** [View on Google Play](https://play.google.com/store/apps/details?id=com.kouji1981.time&hl=en&gl=us) - **Dev Site:** [Official Website](https://www.koutheend.com/) - **Sources:** Developer website content, App store metadata, User reviews. ## Related Intel Reports - [*Dash Calc: Simple Fast Math*](https://marlvel.ai/apps/dash-calc-simple-fast-math) (Enbright LLC) — 5.0/5 Rating | Excellent Sentiment - [*Age Calculator & Date of Birth*](https://marlvel.ai/apps/age-calculator-date-of-birth-2) (ElQube Tech) — 4.5/5 Rating | N/A Sentiment - [*Age Calculator – Date Counter*](https://marlvel.ai/apps/age-calculator-date-counter) (Mustafa Kulac) — N/A Rating | N/A Sentiment - [*Time Duration Calculator*](https://marlvel.ai/apps/time-duration-calculator) (俊华 罗) — 5.0/5 Rating | Mixed Sentiment - [*CalcFast*](https://marlvel.ai/apps/calcfast) (Hannes Sverrisson) — 4.2/5 Rating | N/A Sentiment - [*Free VPN by Free VPN .org™*](https://marlvel.ai/apps/free-vpn-by-free-vpn-org) (Free VPN LLC) — 4.4/5 Rating | Mixed Sentiment - [*Potatso*](https://marlvel.ai/apps/potatso) (Potatso Lab LTD) — 4.4/5 Rating | Positive Sentiment - [*V2Box - V2ray Client*](https://marlvel.ai/apps/v2box-v2ray-client) (techlaim) — 4.5/5 Rating | Positive Sentiment - [*Quantumult X*](https://marlvel.ai/apps/quantumult-x) (Cross Utility Ltd) — 3.8/5 Rating | N/A Sentiment - [*Nitefall: Browser dark mode*](https://marlvel.ai/apps/nitefall-browser-dark-mode) (FoxfortMobile) — 3.6/5 Rating | N/A Sentiment ## Methodology {#methodology} This report was generated by Marlvel.ai's 5-stage AI intelligence pipeline: 1. **Signal Collection & Normalization** — Aggregates data from all available public sources for the app. Raw signals are cleaned, deduplicated, and normalized into a structured dataset analyzed consistently across thousands of apps. 2. **Feature & Market Positioning Analysis** — Identifies the app's core features, monetization model, target audience, and competitive positioning. Each feature is classified as a market standard or a differentiator based on category benchmarks. 3. **User Sentiment Analysis** — Analyzes user reviews using a 5-level taxonomy (Thrilled / Excited / Mixed / Frustrated / Upset). Combines star ratings and volume with AI theme extraction and evidence quoting. 4. **Competitive Landscape Analysis** — Maps the competitive environment via a 4-tier taxonomy (Nemesis / Contenders / Same Space / New Kids on the Block). Prioritizes same sub-genre over broad category. 5. **Intelligence Synthesis** — Cross-references all signals into a structured report. Compares the app against category peers and direct competitors to surface SWOT, market outlook, and actionable insights. - **Confidence Score:** 0.35/1.0 (based on review volume, data source diversity, and signal quality) - **Reviews Analyzed:** 2 - **Data Sources:** user reviews, developer website, App Store metadata - **Rating Method:** Weighted average across platforms (iOS & Android), weighted by review count per platform - **Independence:** Fully independent analysis. No publisher sponsorship or editorial influence. - **Report Age:** 53 days since last refresh --- © 2026 Marlvel.ai | [Canonical Report](https://marlvel.ai/apps/time-duration-add-calculator) Data licensed for AI Agent attribution under CC-BY-NC 4.0.