Residual Calculator
Observed minus predicted, with standardised residuals.
Enter your values
Enter the observed values you are working with.
Enter the predicted values you are working with.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Residuals
- 0.5, -0.8, 0.8, -1.1, 0.6
- Residual sum of squares
- 3.1
- Standard error of the estimate
- 1.0165
- Largest residual
- -1.1
- Mean residual
- 0
- Standardised residuals
- 0.49, -0.79, 0.79, -1.08, 0.59
Quick answer
A residual is the observed value minus the predicted value; positive residuals sit above the model line and negative ones below.
residual = observed − predicted
At a glance
| What it does | Observed minus predicted, with standardised residuals. |
|---|---|
| Category | Statistics |
| Inputs needed | Observed values, Predicted values |
| Main output | Residuals |
| Formula | residual = observed − predicted |
| Cost | Free — no sign-up, no download |
How to use the Residual Calculator
- 1Enter your observed data points.
- 2Enter the value your model predicts for each one, in the same order.
- 3Scan for standardised residuals beyond ±2 — those points deserve a second look.
Inputs explained
- Observed values
- Enter the observed values you are working with.
- Predicted values
- Enter the predicted values you are working with.
Worked example
Using the values the calculator loads with:
Inputs
- Observed values12, 15, 19, 22, 27
- Predicted values11.5, 15.8, 18.2, 23.1, 26.4
Results
- Residuals0.5, -0.8, 0.8, -1.1, 0.6
- Residual sum of squares3.1
- Standard error of the estimate1.0165
- Largest residual-1.1
- Mean residual0
- Standardised residuals0.49, -0.79, 0.79, -1.08, 0.59
Frequently asked questions
What should a residual plot look like?
A shapeless cloud around zero. Curves, funnels or trends mean the model is missing something.
Should the mean residual be zero?
For a fitted least-squares line, yes, essentially. A clearly non-zero mean means the predictions are biased.
What do I need to enter into the Residual Calculator?
Just 2 values: observed values, predicted values. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Residual Calculator work out the answer?
A residual is the observed value minus the predicted value; positive residuals sit above the model line and negative ones below. It applies the formula residual = observed − predicted and shows the working so you can check each step by hand.
Is the Residual Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.