# Curve-Fit — Curve Fitting by Least Squares

> Least squares regression analysis for data curve fitting. (iPhone/iPad app by Bjarne Berge.)

- Source: https://appshunter.io/ios/app/curve-fit/id1450077815 (this page in markdown: same URL + `.md`)
- Developer: [Bjarne Berge](https://appshunter.io/developer/1209858941)
- Category: Productivity, Utilities
- Price: $0.99 with in-app purchases
- Rating: 5.00/5 from 1 App Store ratings
- Age rating: 12+
- Requires: iOS 15.6 · 1 MB
- Languages: English
- Released: 2019-02-27
- Data updated: 2026-07-05
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/curve-fit/id1450077815/reviews.md

## What is Curve?

'CurveFit' uses regression analysis by the method of least squares to find best fit for a set of data to a selected equation.

The curve-fitting technique used in this app is based on regression analysis by the method of least squares.  The free version fits a straight line through a data-set using least squares analysis.

One In-App purchase is required to fit the other equations to the data set:
Straight Line 	        : Y =	C0 + C1*X (free)				
Power Curve		: Y =	C0 + X^C1			Exponential I		: Y =	C0 * EXP(C1*X)
Exponential II		: Y =	C0 * X * EXP(C1*X)
Hyperbolic		: Y =	(C0 + C1*X)/(1 - C2*X)	
Square Root		: Y =	C0 + C1*SQRT(X)
Polynomial		: Y = 	C0 + C1*X + --- + CN*X^N   		
Exponential Poly	: Y =	C0 * EXP(C1*X + --- + 
Natural Log		: Y =	C0 + C1*(LN(X)) + --- + 
Reciprocal		: Y = 	C0 + C1/X + --- + CN/X^N 
 	 	
Most literature deals with least squares analysis for straight lines, 2nd degree polynomials, and functions that can be linearized.  The input-data is transformed into a format that the can be put into linear forms with undetermined constants.  These types of equations are applicable for least-squares regression.

The regression routine is needed for determining values for the set of unknown quantities C1, C2,- - - ,Cm in the equation: 

    Y = C1 x F1(X) + C2 x F2(X) + - - - + Cm x Fm(X)              

The constants are determined to minimize the sum of squares of the differences between the measured values (Y1, Y2, - - - , Yn) and the predicted equation Yc = F(X) which is found by curve-fitting the given data.  

The principle of least squares is to find the values for the unknowns C1 through Cm that will minimize the sum of the squares of the residuals:
 
        n
	∑(ri) =  r12 +  r22 + - - - + rn2 = minimum      
       i=1

This is done by letting the derivative of the above equation equal zero.  Thereby there will be generated as many algebraic equations as given data points, and the number of equations will be larger than unknowns.

## Key features

- Least squares regression analysis
- Multiple equation fitting options
- Data set analysis
- Free straight-line fitting
- In-app purchase for advanced equations

## Pricing and in-app purchases

Base price: $0.99.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Curve-Fit | $2.99 | one-time |



## Frequently asked questions about Curve

### What equations can Curve-Fit fit to data?

Curve-Fit offers straight-line fitting for free. An in-app purchase unlocks additional equation types including Power Curve, Exponential I & II, Hyperbolic, Square Root, Polynomial, Exponential Poly, Natural Log, and Reciprocal.

### How does Curve-Fit perform curve fitting?

Curve-Fit uses regression analysis by the method of least squares. This technique finds the best fit for a set of data to a selected equation by minimizing the sum of the squares of the differences between measured and predicted values.

### What is the price of Curve-Fit?

The base app is free. An in-app purchase is required to unlock advanced curve fitting equation options. The app is priced at $0.99.

### What devices does Curve-Fit support?

Curve-Fit is available for iPhone and iPad devices.

### How often is Curve-Fit updated?

The latest version is 7.0, last updated on February 9, 2026. This indicates a recent update, suggesting ongoing support and development.

### What is the age rating for Curve-Fit?

Curve-Fit has an age rating of 12+, making it suitable for a teenage audience and older.

### What do users like about Curve-Fit?

Based on the provided rating, users highly value Curve-Fit, as evidenced by its 5.0-star rating from 1 review. This suggests a positive user experience with its functionality.

### Does Curve-Fit have ads?

No, Curve-Fit does not contain advertisements. The app is ad-free.

## Version history (last 3 releases)

### 7.0 — 2026-02-09

Updated with Xcode 26.

### 6.0 — 2020-11-23

Upgraded to latest IOS SDK
Minor Bug-fixes
Added 'Share' button to enable sharing, saving and printing of graph/data
Changed color-scheme to work in Dark Mode
Updated layout and fonts to work better with iPads (larger fonts/better layout)

### 4.0 — 2019-02-26

No release notes.

## Apps similar to Curve

| App | Rating | Price | Category |
| --- | --- | --- | --- |
| [SPC 2026](https://appshunter.io/ios/app/spc-2026/id6765859114) | — | Free | Productivity |
| [Zero-Sum Game Calculator](https://appshunter.io/ios/app/zero-sum-game-calculator/id1536945062) | 5.0 (2) | Free | Productivity |
| [Chinese Birthdays](https://appshunter.io/ios/app/chinese-birthdays/id910739193) | 3.7 (3) | $0.99 | Productivity |
| [SMS Scheduler: Text to Self](https://appshunter.io/ios/app/sms-scheduler-text-to-self/id6474932426) | 3.5 (2) | Free | Productivity |
| [Talking Timers: Voice & Multi](https://appshunter.io/ios/app/talking-timers-voice-and-multi/id6759304310) | — | Free | Productivity |
| [RPN-32 CE](https://appshunter.io/ios/app/rpn-32-ce/id1082637146) | 5.0 (8) | $1.99 | Productivity |

## More apps by Bjarne Berge

- [Gas-Liquid Leak](https://appshunter.io/ios/app/gas-liquid-leak/id1209858942)
- [AGA-3 Orifice](https://appshunter.io/ios/app/aga-3-orifice/id1350504597)
- [ISO-5167](https://appshunter.io/ios/app/iso-5167/id1356345079)
- [Gas-Liquid RO](https://appshunter.io/ios/app/gas-liquid-ro/id1374664837)
- [Line-Fit](https://appshunter.io/ios/app/line-fit/id1448053643)

All apps by Bjarne Berge: https://appshunter.io/developer/1209858941

## Related topics

[linearity curve](https://appshunter.io/ios/topics/linearity-curve)

---

*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 2026-07-05.*