# RF Calc JP — RF power, dB, VSWR calculator

> RF power, dB, VSWR calculator (iPhone/iPad app by Hashimoto Yoshikazu.)

- Source: https://appshunter.io/ios/app/rf-calc-jp/id6815598081 (this page in markdown: same URL + `.md`)
- Developer: [Hashimoto Yoshikazu](https://appshunter.io/developer/6790925881)
- Category: Utilities, Education
- Price: Free with in-app purchases
- Age rating: 4+
- Requires: iOS 26.0 · 4 MB
- Languages: American English, Japanese
- Released: 2026-10-02
- Data updated: 2026-10-14

## What is RF Calc JP?

RF Calc JP is a practical calculator for amateur radio and RF work, for iPhone and iPad. Its signature feature: apply gains and losses (dB) to an absolute power value (W, mW, dBm …) in sequence — follow a signal from the transmitter through cable loss and amplifier gain to the final output, right on the keypad.

KEY FEATURE: MIX ABSOLUTE VALUES WITH dB
Enter "1 W − 3.8 dB" and it instantly shows 26.2 dBm (= 0.4169 W = 416.9 mW). Working with absolute values (W/dBm) and relative values (dB) in a single line matches how you actually reason about a link.

FEATURES
• Power / dBm: convert among W / mW / µW / nW / dBm / dBW. Enter one value and see the rest at once (e.g., 1 W = 1000 mW = 30 dBm = 0 dBW).
• RF Chain: start from an absolute power, then stack each stage's gain (+dB) or loss (−dB): TX output → cable loss → amplifier gain → final output. See every stage and name each one.
• Voltage: convert among V / mV / µV / nV and dBV / dBmV / dBµV. Set an impedance (default 50 Ω; 75/600 Ω or custom) to convert to power/dBm. Choose RMS / Peak / Peak-to-Peak as the reference.
• Unit Converter: convert power and voltage units together, showing multiple units at once.
• dB Converter: convert between dB and power/voltage ratios (e.g., +3 dB → power ratio ≈1.9953 / voltage ratio ≈1.4125).
• VSWR: convert among VSWR, reflection coefficient |Γ|, return loss, reflected power (%), and mismatch loss.
• Power Efficiency: transmitter efficiency from DC voltage, current and RF output (e.g., 13.8 V × 20 A with 100 W RF → about 36.2%). Reverse modes give the required DC current or the expected RF output.

BUILT RIGHT
• All internal math is double precision and is never rounded mid-calculation — rounding happens only for display, so chained calculations stay accurate.
• Results appear in several related units at once. Set the number of digits and engineering (SI-prefix) notation in Settings.
• Save a calculation history on device to review later.
• Each calculator keeps its input when you switch. Attenuator (ATT) correction and large text sizes (Dynamic Type) are supported.

WHO IT'S FOR
• Anyone building a quick link budget from the rig to the antenna
• Moving between voltage and power (dBm)
• Converting VSWR and return loss without mental math
• RF and electronics work that lives in dB and gain

PRIVACY
RF Calc JP collects no personal data and does no tracking. It runs fully offline with no account. Your calculation history is stored only on your device.

SUBSCRIPTION
All features are available via an auto-renewing subscription (¥200/year in Japan; equivalent local pricing elsewhere), with a 7-day free trial. Cancel at least 24 hours before the trial ends to avoid charges. Manage or cancel anytime in Settings > Apple ID > Subscriptions.

A simple, accurate RF calculator for everyday operating and design. Feedback is welcome. 73!

■ Terms & Privacy
Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Privacy Policy: https://jpanhamlogapp.github.io/rfcalcjp/privacy.html

## Pricing and in-app purchases

Base price: Free.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| RF Calc JP Pro (Yearly) | $0.99 | per year |


## Is RF Calc JP safe?

Not enough ratings yet to assess RF Calc JP.

## Is RF Calc JP legit?

RF Calc JP appears legitimate, with a few gaps. The AppsHunter Legitimacy Score for RF Calc JP is 65 out of 100 points across 7 verification signals from App Store and developer data.


## Version history (last 2 releases)

### 1.1.0 — 2026-10-08

■ New: Power Efficiency
Calculate transmitter efficiency from DC voltage, current and RF output. Reverse modes also give the required DC current or the expected RF output. Open it from the Power Efficiency button on the Power screen.

■ Power improvements
• Expressions can start with dB (e.g. −50 dB + 23 dBm)
• ATT correction: lock the attenuation to show the corrected value
• W / mW / µW chosen automatically for the value

■ Usability
• Each calculator keeps its input when you switch
• Collapsible keypad; long-press ⌫ to clear all
• ÷ added to Voltage
• Better layout with larger text sizes (Dynamic Type)
• iPhone is now portrait only

### 1.0 — 2026-10-02

No release notes.

## More apps by Hashimoto Yoshikazu

- [HamLogJP - 無線交信ログ帳](https://appshunter.io/ios/app/hamlogjp/id6790925699)
- [DitLog](https://appshunter.io/ios/app/ditlog/id6806041531)

All apps by Hashimoto Yoshikazu: https://appshunter.io/developer/6790925881

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-10-14.*