Kaplan Meier Survival Calculator
Kaplan Meier estimator online with survival curve, log-rank test and median survival time.
When to use it
Use for time-to-event data with right-censoring (medical follow-up, equipment failure, customer churn, plant survival under stress). Estimates the survival function S(t) without assuming a parametric form. Pair with a log-rank test to compare groups.
When NOT to use it
Do not use when you need to adjust for covariates; use Cox proportional hazards instead. Do not use for left-truncated or interval-censored data without explicit handling. The log-rank test loses power when survival curves cross; in that case use a Renyi or generalised Wilcoxon test.
What you get
Kaplan-Meier survival curve per group with Greenwood-formula 95 percent confidence bands; median survival time per group with its 95 percent CI (or NA when the curve does not cross 0.5); number at risk over time; log-rank chi-square and p comparing groups; an at-risk table beneath the curve.
How to interpret the output
S(t) is the probability of surviving beyond time t. A wider CI means fewer subjects still at risk. Median survival is the time at which S(t) crosses 0.5. A significant log-rank rejects the null of identical survival across groups (Mantel 1966). Crossing curves invalidate the proportional-hazards assumption; in that case avoid log-rank conclusions about overall superiority.
Common pitfalls
- Reporting median survival without its CI.
- Using log-rank when survival curves cross (consider Renyi).
- Confusing right-censoring (subject still alive at end of follow-up) with dropout (missingness).
- Forgetting the at-risk table; readers cannot judge precision without it.
Try it in StatVeda
The Kaplan-Meier Survival + Log-Rank engine runs entirely in the browser. No signup, no install, no data sent to a server. Paste your data, hit Run, copy the output.
Open Kaplan-Meier Survival + Log-RankReferences
- Kaplan, E. L. and Meier, P. (1958). Nonparametric estimation from incomplete observations. Journal of the American Statistical Association, 53(282), 457 to 481.
- Mantel, N. (1966). Evaluation of survival data and two new rank order statistics arising in its consideration. Cancer Chemotherapy Reports, 50(3), 163 to 170.
- Klein, J. P. and Moeschberger, M. L. (2003). Survival Analysis: Techniques for Censored and Truncated Data, 2nd edition. Springer, New York.