RMSE Calculator

Measure prediction accuracy with clear, stepwise RMSE insights. See errors, squared errors, and summary metrics. Download reports in CSV or PDF whenever needed today.

Calculator

Paste numbers separated by commas, spaces, or new lines.
Must match the Actual count, in the same order.
Use one weight per pair. Negative values are treated as 0.
CSV headers supported: actual, predicted, weight.
Controls rounding in the results and downloads.
Weighting uses sum(weights) automatically.
Reset

Formula used

Root Mean Square Error (RMSE) measures the typical size of prediction error. For paired values y (actual) and ŷ (predicted):

Error: eᵢ = ŷᵢ − yᵢ
MSE = (1 / d) · Σ(eᵢ²)
RMSE = √MSE

Here, d is the denominator you choose: n (default) or n−1. If you provide weights, the calculator uses d = Σwᵢ.

How to use this calculator

  1. Enter your Actual values and matching Predicted values.
  2. Optional: add Weights if some pairs matter more.
  3. Or upload a CSV with columns named actual and predicted.
  4. Choose decimals and denominator, then click Calculate RMSE.
  5. Review RMSE, MSE, MAE, and the detailed error table.
  6. Use Download CSV or Download PDF for reporting.

Example data table

Example pairs and squared errors (RMSE ≈ 0.6124 when using n).

# Actual Predicted Error (Pred−Act) Squared Error
132.5-0.50.25
2-0.500.50.25
32200
47811

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.