Cox Regression Calculator
Estimate how several predictors relate to the hazard of an event over time, adjusting for each other. Text predictors are dummy coded automatically.
Updated · By Bibin XavierData 160 × 6
| Patienttext · 160 levels | Treatmenttext · 2 levels | Agenumeric | Stagenumeric · coded | Time_Monthsnumeric | Eventnumeric · coded |
|---|---|---|---|---|---|
| P001 | Standard | 71 | 1 | 10.5 | 0 |
| P002 | New | 71 | 3 | 23.9 | 1 |
| P003 | Standard | 70 | 2 | 40 | 1 |
| P004 | New | 68 | 3 | 3.2 | 1 |
| P005 | Standard | 72 | 3 | 18.1 | 0 |
| P006 | New | 55 | 1 | 9.1 | 1 |
| P007 | Standard | 73 | 3 | 4.6 | 1 |
| P008 | New | 66 | 3 | 32 | 0 |
Variables and options
Results
160 rows · example dataVariables in the equation
| Covariate | B | SE | Wald | p | Hazard ratio | 95% CI for HR |
|---|---|---|---|---|---|---|
| Treatment [Standard] | 0.547 | 0.238 | 5.30 | .021 | 1.728 | [1.085, 2.752] |
| Age | 0.018 | 0.013 | 1.90 | .168 | 1.018 | [0.992, 1.045] |
| Stage | 0.157 | 0.165 | 0.90 | .342 | 1.170 | [0.847, 1.617] |
Note. Breslow method for tied event times. HR above 1 means a higher hazard (shorter survival).
Hazard ratios with 95% CI
Interpretation
Treatment [Standard] increases the hazard by 73% (HR = 1.73), holding the other covariates constant.
How to cite this tool
Using these results in a thesis, journal article, report or class assignment? Please cite this free tool so others can find it. It keeps the site free.
APA 7
Xavier, B. (2026). Cox Regression Calculator [Web application]. FreeStatisticalTools.com. https://freestatisticaltools.com/cox-regression/
BibTeX
@software{xavier_coxregression_2026,
author = {Xavier, Bibin},
title = {Cox Regression Calculator},
publisher = {FreeStatisticalTools.com},
year = {2026},
url = {https://freestatisticaltools.com/cox-regression/},
note = {Web application}
}Suggested sentence for your methods section: “The analysis was carried out with the free Cox Regression Calculator tool on FreeStatisticalTools.com (Xavier, 2026).”
What is Cox regression?
Cox regression models the hazard of an event over time as a function of several predictors, giving adjusted hazard ratios. It is the standard multivariable method for survival data.
When to use Cox regression
Use it to test several predictors of time to an event at once, such as treatment, age and disease stage.
Assumptions
- Proportional hazards: the effect of each covariate is constant over time.
- Censoring is non-informative, and there are about 10 events per covariate.
How to use this tool
- Enter your data. Paste columns from Excel, Google Sheets or SPSS with variable names in the first row, or upload a CSV or Excel file. The example data shows the expected layout.
- Choose the variables. Select the time, event status, value meaning the event occurred and covariates.
- Read the results. Results update automatically. Read the plain-English interpretation, then use Copy table to paste APA-style tables into Word and Copy for the results sentence.
Frequently asked questions
How do I interpret a hazard ratio?
A hazard ratio of 2 means twice the instantaneous risk of the event; 0.5 means half the risk, holding other covariates constant.
What is the proportional hazards assumption?
That each covariate’s effect on the hazard is constant over time. Crossing survival curves suggest it is violated.
How are tied event times handled?
With the Breslow approximation, the default in several statistics packages.
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