Comparison

Curvature vs Octopus Watch

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

Head to head
About

Curvature

This app provides advanced tools for calculating and visualizing earth measurements, including curvature, horizon distance, and drop distance. It features a redesigned interface with precision mapping, data persistence, and a knowledge hub with research resources.

Highlights
  • Advanced Earth Calculators
  • Graphic Result Visualization
  • Precision Mapping Tools
  • Data Persistence with SwiftData
  • Expanded PDF Library
  • Universal Unit Converter
  • Save & Export Calculations
Features
Read full description

Curvature is a geometry and visibility toolkit for anyone who wants to test what a curved or flat Earth would predict, with every formula documented and every assumption stated. THE CALCULATOR Enter observer height, target height and surface distance. Curvature returns the surface horizon, tangent-plane drop, midpoint bulge, horizon dip, surface tilt and the hidden and visible portions of the target, in metres or feet, kilometres or miles. Choose refraction off, four published coefficients or your own k from 0 to 0.5, and compare any result side by side with the pure geometric case. Drag the observer, target and distance directly on an exaggerated profile, or switch to a true-scale view with a magnified detail inset. Uncertainty ranges recalculate across your stated input tolerances so you can see whether a sighting is robust. THE MAP Drop rulers and points of interest on standard, satellite or hybrid maps. Rulers report geodesic surface distance and initial bearing in degrees or NATO mils, search for places, fit the view and send endpoints straight to the calculator. Optional terrain lookup prefills ground elevations from SRTM data with the datum and limits spelled out. THE 3D MODEL EXPLORER (NEW) Explore three scenarios with the same observer, date and time: the classical north-polar disc, a south-polar projection comparison and a WGS84 reference ellipsoid. The globe uses dated geometric ephemerides from the open-source Astronomy Engine, including sidereal rotation, precession, nutation, seasons, real Earth-Sun and Earth-Moon distances and lunar illumination, validated against JPL Horizons and US Naval Observatory data. Place the observer anywhere, read elevation, bearing, slant distance and angular diameter for the Sun and Moon, then open the observer sky to see both at their calculated angular size. A comparison sheet lists all three models for the same inputs. Each scene labels what is sourced, what is an app assumption and what is not simulated. REPORTS AND ANALYSIS Export an illustrated PDF report with inputs, coordinates, assumptions, uncertainty bounds and the calculation version, or copy a structured text summary. On supported devices, Apple Intelligence can draft a plain-language analysis that never alters the calculated numbers. REFERENCE LIBRARY Read bundled historical and technical PDFs with page bookmarks, find and go-to. Browse fifty curated web links covering tools, research, forums and video from every perspective, plus references, worked formulas for the calculator, map and explorer, and an indexed glossary of more than eighty terms. YOUR DATA Saved observations, rulers, points, links, imported PDFs and reading positions sync privately through iCloud on signed-in devices, with portable backup and restore. No account, tracking or advertising. Curvature does not tell you what to believe. It shows what each model predicts, how that was calculated and where the model stops.

About

Octopus Watch

Easily manage your Octopus Energy tariffs, track electricity rates, and identify optimal times to use appliances or charge your EV. Offers insights into usage, weather impacts, and export earnings. Optional subscription unlocks advanced features like 48-hour rate predictions and carbon integration.

Highlights
  • Track current and upcoming electricity rates
  • Identify cheapest times for appliances/EV charging
  • View historic usage and micro metrics
  • Receive rate change alerts
  • Compare tariffs
  • Export data to CSV
  • 48h Agile rate predictions (subscription)
Features
Read full description

Octopus Watch is the easiest tool to manage the (smart) tariffs provided by Octopus Energy in the UK. Octopus Watch is a paymium app for iOS offering both a standard version as a one-time purchase, and an optional subscription with additional features. Ready to supercharge your savings? Save significantly on your electricity bill, regardless of whether you're on Agile, Go, Cosy, Flux, Tracker, or any fixed tariffs (basic or eco 7). Thinking of joining Agile? Log into the app with just your postcode and check out local rates. If you want to see your consumption history, you'll need an Octopus Energy account and an active smart meter. Please note that support for Intelligent and Intelligent Go is currently limited, with only default off-peak times available. For the latest status on tariff support check out the wiki: https://wiki.smarthound.uk/octopus-watch/tariffs/ . With the standard version of Octopus Watch, you'll have all the tools at your fingertips to effectively manage your tariff: • View your current rates in an instant (including for gas trackers). • View your current electricity rates directly on your Apply Watch! • See all your upcoming rates in an easy chart and table. • Instantly get the cheapest times to run appliances or charge your EV, and save big! • Use the beautiful widget for current and upcoming prices on your home screen. • Receive alerts when the next day's Agile rates are available. • See your historic day-by-day usage. • Use the new micro metrics to quickly see trends in your usage. • See when your meter fails and how much data is missing. • Understand how weather influences your usage. • One tap comparison to see how your tariff compares to Agile, Go, and SVT. • Check your earnings from export (only available with an export meter). • Various options to change the app defaults to best suit your needs! • Export cleaned data to CSV for easy use in other apps such as Microsoft® Excel®. Want even more? A single subscription gets you access to these amazing features: • Up to 48h Agile rate predictions – plan your usage effectively and save even more! • If you have an export meter, also receive Agile export rate predictions. • Access 7-day weather forecasts across Great Britain for even better planning. • Instant notifications when next day's Agile prices fall below your chosen threshold. • Identify optimal half-hour blocks throughout the day to charge your EV or run appliances. • Carbon integration - see your environmental impact both now and in the past. • View your electricity generation regionally or nationally, and adjusted to your usage. • Choose the best slot based on either price or lowest carbon emissions on the grid. • One tap comparison to see how your tariff compares to most smart tariffs. • Advanced micro metrics over 14 or 28 days, including subscription-only metrics. • Day details – see your exact usage along with numerous statistics on a day-by-day basis. • Day details – see exactly which data is missing when your meter stops reporting. • Micro-optimise your usage with half-hour details within the app. • Generate straightforward electricity reports for any period in the last year. • Generate detailed gas reports, including heat pump efficiency information, for the last year. Thanks to Family Sharing you can install the app on all devices within the same family. Install it on your iPhone for an easy pocket reference, run it from your iPad to see the beautiful rate graph and double column table, or see the current rate with a flick of your wrist on your Apple Watch with dozens of complications to choose from. The choice is yours! Octopus Watch also supports subscription sharing, so one subscription gives you access to all the extras on all the iPhones and iPads in your household.

Screenshots

Curvature4 screens
Octopus Watch4 screens

Verdict

The call

The clearest difference is rating: Curvature at 5.0 against Octopus Watch's 4.0. Curvature also leads on review sentiment (100% vs 65%) and in-app purchases (none vs 2). Octopus Watch's advantage is update cadence (every 3 weeks vs every 5 months). On price, ratings volume, ads and device support 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

Curvature costs $1.99 and Octopus Watch $1.99 up front. Octopus Watch sells 2 in-app purchases, starting at $1.99 per month. Curvature asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Curvature holds the better App Store score, 5.0 against 4.0. Both are backed by a comparable volume of ratings — 2 and 1 respectively. Written reviews point the same way: 100% of Curvature's written reviews are positive against 65% of Octopus Watch's.

UpkeepUpdate frequency

Curvature ships an update every 5 months, Octopus Watch every 3 weeks. The most recent releases landed on October 24, 2026 and October 29, 2026 respectively.

Scorecard5 real differences · 5 level
Curvature versus Octopus Watch: the parameters behind the verdict, then further details
ParameterCurvatureOctopus Watch
Price$1.99$1.99
Rating5.0 (2 ratings) — better4.0 (1 ratings)
Positive reviews100.0% of reviews — better64.6% of reviews
Number of ratings2 — better1
Update frequencyEvery 5 monthsEvery 3 weeks — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationPaidFree with in-app purchases — better
DevicesiPhone, iPadiPhone, iPad, Apple Watch — better
Requires iOS17.616.1 — better
Further details — not scored
Size116 MB19 MB
Age rating4+4+
DeveloperSteven WilkinsonKim Bauters

Customer experience

Curvature

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews2 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Octopus Watch

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews79 reviews
Positive64.6%
Neutral10.1%
Negative25.3%

In-app purchases

None

Curvature

No in-app purchases

2 purchases

Octopus Watch

Subscriptions2
  • 1 Month Subscription$1.991 Month
  • 1 Year Subscription$11.991 Year

Questions

Is Curvature free?
Curvature costs $1.99, with no in-app purchases.
Is Octopus Watch free?
Octopus Watch costs $1.99, and also offers in-app purchases.
Which has better reviews, Curvature or Octopus Watch?
Curvature is rated higher. Curvature averages 5.0 out of 5 from 2 ratings, while Octopus Watch averages 4.0 from 1 ratings.
Do Curvature or Octopus Watch have ads?
Neither Curvature nor Octopus Watch shows ads.
Which is updated more often, Curvature or Octopus Watch?
Curvature ships an update every 5 months, and Octopus Watch every 3 weeks. Most recently, Curvature was updated on October 24, 2026 and Octopus Watch on October 29, 2026.

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