Zulu Time vs Interpolator
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Zulu Time
This app displays local and UTC (Zulu) time, along with multiple time zones, on your iPhone, Apple Watch, and iPad. It offers widgets for quick access and features for calculating future or past times with offsets, simplifying timezone conversions for various professions.
- Display local and Zulu (UTC) time
- Multiple time zone display
- Home and Lock Screen widgets
- Apple Watch complications
- Future/past time offset calculations
- Time zone conversion
Read full descriptionHide full description
An iPhone, Apple Watch and iPad app to see Local and Zulu time (GMT) or multiple time zones in a single glance. Includes Widgets for both the iPhone and Apple Watch. Useful for pilots in getting weather briefings and filing flight plans, or Ham radio operators to do timezone conversions. No more worrying about getting the timezone offset correct or Daylight Savings Time conversions. Easily convert from different time zones, including times in the future or past. On the iPhone: - Home and Lock Screen widgets - The Zulu Time page gives a quick view of both Zulu and Local times - The Offset Time page allows you to see Zulu and local time either in the future or past by entering an offset via the Offset button. Tapping either Zulu or Local times will allow you to enter a time in the future or past, synchronizing both Local and Zulu times with that offset. The offset only applies to this view (except on the iPad the offset applies to everything on the page) - The Multiple Zones page allows you to add as many time zones as you wish in a scrolling view. Clicking on any Time Zone will allow you to change it. on iPad: All information is combined on one screen. You have user customizable time zones on the right hand side. On the left, you have Zulu and Local time and one customizable time zone. The offset to see future or past time can be done via the Offset button or tapping any of either the Zulu, Local or Custom time buttons on the left. On the Watch: Complications available in all watch faces making for glanceable ZuluTime and access to the app, which gives offset able time computation.
Interpolator
Easily find values within tables using interpolation for two or three rows. This utility app simplifies calculations without needing a separate calculator, making it ideal for various table-based environments.
- Two-row interpolation
- Three-row interpolation
- Table value lookup
- No calculator needed
- Cargo surveyor tool
- General table use
Read full descriptionHide full description
This is a small app which makes it very easy to look up values in tables (math etc) when you have to interpolate both in two and in three rows. No more need for a calculator to interpolate manually. This app was designed primarily for cargo surveyors working with tank calibration tables, but the app does have its application in any environment where tables are used. As of 13th January 2015, this app has become FREE until further notice.
Screenshots
Verdict
The clearest difference is price: Interpolator at Free against Zulu Time's $0.99. Interpolator also leads on iOS requirement (12.0 vs 17.6). Zulu Time's advantage is ratings volume (2.6K vs 74) and chart position (#127 vs unranked). On rating, update cadence, ads and in-app purchases 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
Interpolator is free to download; Zulu Time costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.
On the App Store both sit at effectively the same score — 4.8 for Zulu Time against 4.9 for Interpolator. That said, the two scores are not equally well evidenced: Zulu Time has 2.6K ratings behind it against 74, so its average is the more settled of the two. Written reviews are what separate them: 79% of Zulu Time's written reviews are positive against 67% of Interpolator's.
Zulu Time ships an update every 3 months, Interpolator every 4 months. The most recent releases landed on October 18, 2026 and October 12, 2026 respectively.
| Parameter | Zulu Time | Interpolator |
|---|---|---|
| Price | $0.99 | Free — better |
| Rating | 4.8 (2.6K ratings) | 4.9 (74 ratings) — better |
| Positive reviews | 78.6% of reviews — better | 66.7% of reviews |
| Number of ratings | 2.6K — better | 74 |
| Update frequency | Every 3 months — better | Every 4 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Best chart rank | #127 — better | — |
| Devices | iPhone, iPad, Apple Watch — better | iPhone, iPod |
| Requires iOS | 17.6 | 12.0 — better |
| Further details — not scored | ||
| Size | 16 MB | 18 MB |
| Age rating | 4+ | +4 |
| Developer | Derek Spears | ron mooring |
Customer experience
Zulu Time
Interpolator
Bugs and requests
Zulu Time
Reported bugs
3 issues- Complication freezes after a few days
- Zulu time loses accuracy over time on Apple Watch
- Widget not updating local time properly
Requested features
5 requests- Add alarm feature
- Allow landscape mode for bedside clock view
- Provide option for always-on display
- Add time zone map for quick reference
- Show day of year in display
Interpolator
Not enough reviews yet to summarise bugs or requests.
In-app purchases
Zulu Time
No in-app purchases
Interpolator
No in-app purchases
