# Interpolator vs Tanker

The clearest difference is in-app purchases: Interpolator at none against Tanker's 2. Interpolator also leads on ratings volume (75 vs 1) and iOS requirement (12.0 vs 27.0). Tanker's advantage is update cadence (monthly vs every 4 months). On price, rating, ads and device support there is nothing between them.

Both are free to download. Tanker sells 2 one-off in-app purchases. Interpolator asks for nothing beyond the download.

On the App Store both sit at effectively the same score — 4.9 for Interpolator against 5.0 for Tanker. That said, the two scores are not equally well evidenced: Interpolator has 75 ratings behind it against 1, so its average is the more settled of the two.

Interpolator ships an update every 4 months, Tanker monthly. The most recent releases landed on November 9, 2026 and November 2, 2026 respectively.

## The numbers

| Metric | Interpolator | Tanker |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.9 (75 ratings)](https://appshunter.io/ios/app/interpolator/id635235982/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/tanker-the-sounding-app/id1442173028/reviews)** |
| Number of ratings | **75** | 1 |
| Positive reviews | 66.7% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 4 months | **Monthly** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 18 MB | 20 MB |
| Requires iOS | **12.0** | 27.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [ron mooring](https://appshunter.io/developer/612283157) | [Pearson Smith](https://appshunter.io/developer/1268483172) |

## What reviewers say

### Interpolator

[App page](https://appshunter.io/ios/app/interpolator/id635235982)

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.

**Highlights:** Two-row interpolation, Three-row interpolation, Table value lookup, No calculator needed, Cargo surveyor tool, General table use

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


### Tanker

[App page](https://appshunter.io/ios/app/tanker-the-sounding-app/id1442173028)

This app streamlines the process of calculating marine fuel tank volumes. It eliminates the need for physical sounding tables and manual calculations, providing instant volume lookups with trim corrections automatically applied. Users can manage target fill levels, track fuel transfers, and share tables with their fleet.

**Highlights:** Instant volume lookups, Target fill level setting, CSV import and tank duplication, Unit conversion and safe fill percentages, Bunkering mode for real-time tracking, Offline functionality, Cloud sharing via TankerBase

**Features:** macOS Compatibility, Family Sharing

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Full Version | $4.99 | one-time |
| Tanker Pro Lifetime | $59.99 | one-time |


## Frequently asked questions

### Is Interpolator free?

Interpolator is free to download, with no in-app purchases.

### Is Tanker free?

Tanker is free to download, with in-app purchases available.

### Which has better reviews, Interpolator or Tanker?

Tanker is rated higher. Interpolator averages 4.9 out of 5 from 75 ratings, while Tanker averages 5.0 from 1 ratings.

### Do Interpolator or Tanker have ads?

Neither Interpolator nor Tanker shows ads.

### Which is updated more often, Interpolator or Tanker?

Interpolator ships an update every 4 months, and Tanker monthly. Most recently, Interpolator was updated on November 9, 2026 and Tanker on November 2, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*