0.329114
0.164557
1
0.329114
0.164557
1
This P-Value Calculator converts a t-score into a p-value for quick hypothesis-test interpretation. Enter your t-score and degrees of freedom (df) to get both a two-tailed p-value and a one-tailed p-value (either side).
Note: This version uses a fast approximation designed to stay close to the Student’s t-distribution (especially as df grows). For extremely small df, exact t-distribution calculators may differ slightly.
For Student’s t-tests, p-values come from the t-distribution, which depends on df. Because the distribution is symmetric, we work with |t| and compute tail probabilities.
This calculator uses a df-based transformation of |t| into an adjusted z-like value and then converts it into tail probability using a standard normal CDF approximation.
Smaller p-values indicate that observing a t-score at least as extreme as yours would be less likely under the null hypothesis. Many U.S. use cases compare p-values to 0.05, but context and effect size still matter.
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A t-score of 1 is usually not extreme. Two-tailed p should be well above 0.05.
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A stronger t-score. Two-tailed p is typically around 0.02.
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Using |t| means negative and positive t-scores of the same magnitude give the same p-values.
Use a t-score when the population standard deviation is unknown and sample sizes are smaller. The t-distribution accounts for extra uncertainty through degrees of freedom.
Degrees of freedom often relate to sample size (for example, df = n − 1 in a one-sample t-test). The exact df depends on the test setup.
Two-tailed tests check for differences in both directions (higher or lower than the reference). It’s common when you care about any deviation.
The distribution is symmetric around 0. Using |t| measures extremeness regardless of sign and keeps the p-value logic consistent.
It will be very close for moderate-to-large df. For very small df, exact t-distribution CDF values can differ slightly. If you need exact matching, the platform should support a true t-distribution CDF function.
Roboculator Team
The Roboculator Team explains calculations, planning tools, and practical formulas in clear language for real-life situations.
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