Comparison

Sight Calc vs Celestial Navigator

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

Head to head
About

Sight Calc

This app is a specialized calculator for sight reductions using the Law of Cosines method. It's designed for students learning celestial navigation and requires manual input of LHA, declination, and approximate latitude.

Highlights
  • Law of Cosines sight reduction
  • Manual LHA, declination, and latitude input
  • Input as degrees/minutes or decimal degrees
  • Continuous computation of Hc, Z, and Zn
  • Supports North/South latitude and declination conventions
  • Clear and clear entry functions
  • Convert minutes to decimal degrees
Features
Read full description

Sight Calc is a specialized calculator for calculating sight reductions via the "Law of Cosines" method. It does not use Nautical Almanac data, so you must first compute LHA (Local Hour Angle) and declination, and determine your approximate latitude. It is designed particularly for students learning celestial navigation, such as the Celestial Navigation courses taught by the United States Power Squadrons®. If you are unfamiliar with how to do sight reductions, some good resources are available from the United States Power Squadrons® at www.usps.org. In particular, this calculator is useful in conjunction with Form SR96a, www.usps.org/eddept/n/files/sr96a.pdf Inputs may be entered as two numbers: Degrees - left column Minutes - right column Or enter as decimal degrees (e.g., 44.48833). Sight Calc will prompt you to enter six number in sequence: LHA (degrees) LHA (minutes) Lat (degrees) Lat (minutes) Dec (degrees) Dec (minutes) In v 2.0 you may enter values in any sequence. Hc, Z and Zn are continuously computed and displayed. Be sure to enter North Latitude as a positive number and South Latitude as a NEGATIVE number. Sight Calc will take the absolute value of Latitude in the law of cosines formula, but needs the hemisphere to calculate azimuth (Zn). Similarly, enter Declination as positive if North and negative if South. (Note: this differs from version 1.x of Sight Calc.) If you want to do repeated calculations with some of the same numbers, just enter the changed numbers. To start over fresh at any time, press "C" to clear everything. "CE" key clears the Current Entry. Optionally, use the "o" key to convert minutes to decimal degrees, add that to the degrees field, and clear the minutes field. This has no effect on the calculation. Please report any bugs or suggestions to: sightcalc@nuvocom.com

About

Celestial Navigator

This app assists with celestial navigation training by providing a perpetual almanac, star finder chart with animation, and tools for calculating lines of position and meridian passages. It can utilize device sensors for real-time chart positioning, though a marine sextant is still required for actual navigation.

Highlights
  • Perpetual almanac
  • Animated star finder chart
  • Line of position calculation
  • Meridian passage calculation
  • Real-time sensor integration
  • Celestial object data
Features
Read full description

Celestial Navigation Calculator with - perpetual Almanac - star finder chart with animation. Use phone sensor for altitude. - calculation of lines of position ( intercept/delta ) - celestial object data - meridian passage calculation - running fix support - astronomical position calculations with two or more altitude observations - Hipparchus 150 star catalog - World chart with lines and position Program can be set to use device's sensors (gyro, compass) to position the star finder chart in real time. Capture celestial object approximate altitude. Correct Altitude with a Marine Sextant reading (not included). You still need a marine sextant to do celestial navigation, but the phone sensors may be used for training. Software for iPhone and iPad, with the same features. e-book with manual and celestial navigation tutorial.

Screenshots

Sight Calc4 screens
Celestial Navigator4 screens

Verdict

The call

The clearest difference is price: Celestial Navigator at Free against Sight Calc's $1.99. Celestial Navigator also leads on iOS requirement (11.0 vs 16.0). Sight Calc's advantage is rating (5.0 vs 2.0) and review sentiment (82% vs 43%). On ratings volume, 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

CostPrice · In-app purchases · Ads · Monetization

Celestial Navigator is free to download; Sight Calc costs $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

Sight Calc holds the better App Store score, 5.0 against 2.0. Both are backed by a comparable volume of ratings — 7 and 3 respectively. Written reviews point the same way: 82% of Sight Calc's written reviews are positive against 43% of Celestial Navigator's.

UpkeepUpdate frequency

Sight Calc ships an update every 11 months, Celestial Navigator every 9 months. The most recent releases landed on September 10, 2026 and August 12, 2026 respectively.

Scorecard5 real differences · 5 level
Sight Calc versus Celestial Navigator: the parameters behind the verdict, then further details
ParameterSight CalcCelestial Navigator
Price$1.99Free — better
Rating5.0 (7 ratings) — better2.0 (3 ratings)
Positive reviews82.4% of reviews — better42.9% of reviews
Number of ratings7 — better3
Update frequencyEvery 11 monthsEvery 9 months — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaidFree — better
DevicesiPhone, iPadiPhone, iPad, iPod — better
Requires iOS16.011.0 — better
Further details — not scored
Size1 MB32 MB
Age rating4+4+
DeveloperNUVOCOM INCORPORATEDOmar reis

Customer experience

Sight Calc

All ratings7 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews17 reviews
Positive82.4%
Neutral0.0%
Negative17.6%

Celestial Navigator

All ratings3 ratings
Positive33.3%
Neutral0.0%
Negative66.7%
Written reviews7 reviews
Positive42.9%
Neutral0.0%
Negative57.1%

In-app purchases

None

Sight Calc

No in-app purchases

None

Celestial Navigator

No in-app purchases

Questions

Is Sight Calc free?
Sight Calc costs $1.99, with no in-app purchases.
Is Celestial Navigator free?
Celestial Navigator is free to download, with no in-app purchases.
Which has better reviews, Sight Calc or Celestial Navigator?
Sight Calc is rated higher. Sight Calc averages 5.0 out of 5 from 7 ratings, while Celestial Navigator averages 2.0 from 3 ratings.
Do Sight Calc or Celestial Navigator have ads?
Neither Sight Calc nor Celestial Navigator shows ads.
Which is updated more often, Sight Calc or Celestial Navigator?
Sight Calc ships an update every 11 months, and Celestial Navigator every 9 months. Most recently, Sight Calc was updated on September 10, 2026 and Celestial Navigator on August 12, 2026.

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