ZTable.io - Z-Score Table (Standard Normal Table)

Compute a P-value from a Z-score

ZScore (𝑥)

0.50000 Probability

P(𝑍 < 𝑥)	0.50000
P(𝑍 > 𝑥)	0.50000
P(0 < 𝑍 < 𝑥)	0.00000
P(−𝑥 < 𝑍 < 𝑥)	0.00000
P(𝑍 < −𝑥 or 𝑍 > 𝑥)	1.00000

Probability between two Z-Scores

0.34134 Probability

P(𝑥_min < 𝑍 < 𝑥_max)	0.34134
P(𝑍 < 𝑥_min or 𝑍 > 𝑥_max)	0.65866
P(𝑍 < 𝑥_min)	0.50000
P(𝑍 > 𝑥_max)	0.15866

Z Score Calculator

Test value (𝑋)

Mean value (𝜇)

Standard deviation (𝜎) Standard deviation must be a positive non-zero value.

1.00 Z Score 𝑧 = (𝑋 − 𝜇) ⁄ 𝜎

0.84134 Probability

Negative Z Table

Z	.00	.01	.02	.03	.04	.05	.06	.07	.08	.09
-3.9	0.00005	0.00005	0.00004	0.00004	0.00004	0.00004	0.00004	0.00004	0.00003	0.00003
-3.8	0.00007	0.00007	0.00007	0.00006	0.00006	0.00006	0.00006	0.00005	0.00005	0.00005
-3.7	0.00011	0.0001	0.0001	0.0001	0.00009	0.00009	0.00008	0.00008	0.00008	0.00008
-3.6	0.00016	0.00015	0.00015	0.00014	0.00014	0.00013	0.00013	0.00012	0.00012	0.00011
-3.5	0.00023	0.00022	0.00022	0.00021	0.0002	0.00019	0.00019	0.00018	0.00017	0.00017
-3.4	0.00034	0.00032	0.00031	0.0003	0.00029	0.00028	0.00027	0.00026	0.00025	0.00024
-3.3	0.00048	0.00047	0.00045	0.00043	0.00042	0.0004	0.00039	0.00038	0.00036	0.00035
-3.2	0.00069	0.00066	0.00064	0.00062	0.0006	0.00058	0.00056	0.00054	0.00052	0.0005
-3.1	0.00097	0.00094	0.0009	0.00087	0.00084	0.00082	0.00079	0.00076	0.00074	0.00071
-3.0	0.00135	0.00131	0.00126	0.00122	0.00118	0.00114	0.00111	0.00107	0.00104	0.001
-2.9	0.00187	0.00181	0.00175	0.00169	0.00164	0.00159	0.00154	0.00149	0.00144	0.00139
-2.8	0.00256	0.00248	0.0024	0.00233	0.00226	0.00219	0.00212	0.00205	0.00199	0.00193
-2.7	0.00347	0.00336	0.00326	0.00317	0.00307	0.00298	0.00289	0.0028	0.00272	0.00264
-2.6	0.00466	0.00453	0.0044	0.00427	0.00415	0.00402	0.00391	0.00379	0.00368	0.00357
-2.5	0.00621	0.00604	0.00587	0.0057	0.00554	0.00539	0.00523	0.00508	0.00494	0.0048
-2.4	0.0082	0.00798	0.00776	0.00755	0.00734	0.00714	0.00695	0.00676	0.00657	0.00639
-2.3	0.01072	0.01044	0.01017	0.0099	0.00964	0.00939	0.00914	0.00889	0.00866	0.00842
-2.2	0.0139	0.01355	0.01321	0.01287	0.01255	0.01222	0.01191	0.0116	0.0113	0.01101
-2.1	0.01786	0.01743	0.017	0.01659	0.01618	0.01578	0.01539	0.015	0.01463	0.01426
-2.0	0.02275	0.02222	0.02169	0.02118	0.02068	0.02018	0.0197	0.01923	0.01876	0.01831
-1.9	0.02872	0.02807	0.02743	0.0268	0.02619	0.02559	0.025	0.02442	0.02385	0.0233
-1.8	0.03593	0.03515	0.03438	0.03362	0.03288	0.03216	0.03144	0.03074	0.03005	0.02938
-1.7	0.04457	0.04363	0.04272	0.04182	0.04093	0.04006	0.0392	0.03836	0.03754	0.03673
-1.6	0.0548	0.0537	0.05262	0.05155	0.0505	0.04947	0.04846	0.04746	0.04648	0.04551
-1.5	0.06681	0.06552	0.06426	0.06301	0.06178	0.06057	0.05938	0.05821	0.05705	0.05592
-1.4	0.08076	0.07927	0.0778	0.07636	0.07493	0.07353	0.07215	0.07078	0.06944	0.06811
-1.3	0.0968	0.0951	0.09342	0.09176	0.09012	0.08851	0.08691	0.08534	0.08379	0.08226
-1.2	0.11507	0.11314	0.11123	0.10935	0.10749	0.10565	0.10383	0.10204	0.10027	0.09853
-1.1	0.13567	0.1335	0.13136	0.12924	0.12714	0.12507	0.12302	0.121	0.119	0.11702
-1.0	0.15866	0.15625	0.15386	0.15151	0.14917	0.14686	0.14457	0.14231	0.14007	0.13786
-0.9	0.18406	0.18141	0.17879	0.17619	0.17361	0.17106	0.16853	0.16602	0.16354	0.16109
-0.8	0.21186	0.20897	0.20611	0.20327	0.20045	0.19766	0.19489	0.19215	0.18943	0.18673
-0.7	0.24196	0.23885	0.23576	0.2327	0.22965	0.22663	0.22363	0.22065	0.2177	0.21476
-0.6	0.27425	0.27093	0.26763	0.26435	0.26109	0.25785	0.25463	0.25143	0.24825	0.2451
-0.5	0.30854	0.30503	0.30153	0.29806	0.2946	0.29116	0.28774	0.28434	0.28096	0.2776
-0.4	0.34458	0.3409	0.33724	0.3336	0.32997	0.32636	0.32276	0.31918	0.31561	0.31207
-0.3	0.38209	0.37828	0.37448	0.3707	0.36693	0.36317	0.35942	0.35569	0.35197	0.34827
-0.2	0.42074	0.41683	0.41294	0.40905	0.40517	0.40129	0.39743	0.39358	0.38974	0.38591
-0.1	0.46017	0.4562	0.45224	0.44828	0.44433	0.44038	0.43644	0.43251	0.42858	0.42465
-0.0	0.5	0.49601	0.49202	0.48803	0.48405	0.48006	0.47608	0.4721	0.46812	0.46414

Positive Z Table

Z	.00	.01	.02	.03	.04	.05	.06	.07	.08	.09
0.0	0.5	0.50399	0.50798	0.51197	0.51595	0.51994	0.52392	0.5279	0.53188	0.53586
0.1	0.53983	0.5438	0.54776	0.55172	0.55567	0.55962	0.56356	0.56749	0.57142	0.57535
0.2	0.57926	0.58317	0.58706	0.59095	0.59483	0.59871	0.60257	0.60642	0.61026	0.61409
0.3	0.61791	0.62172	0.62552	0.6293	0.63307	0.63683	0.64058	0.64431	0.64803	0.65173
0.4	0.65542	0.6591	0.66276	0.6664	0.67003	0.67364	0.67724	0.68082	0.68439	0.68793
0.5	0.69146	0.69497	0.69847	0.70194	0.7054	0.70884	0.71226	0.71566	0.71904	0.7224
0.6	0.72575	0.72907	0.73237	0.73565	0.73891	0.74215	0.74537	0.74857	0.75175	0.7549
0.7	0.75804	0.76115	0.76424	0.7673	0.77035	0.77337	0.77637	0.77935	0.7823	0.78524
0.8	0.78814	0.79103	0.79389	0.79673	0.79955	0.80234	0.80511	0.80785	0.81057	0.81327
0.9	0.81594	0.81859	0.82121	0.82381	0.82639	0.82894	0.83147	0.83398	0.83646	0.83891
1.0	0.84134	0.84375	0.84614	0.84849	0.85083	0.85314	0.85543	0.85769	0.85993	0.86214
1.1	0.86433	0.8665	0.86864	0.87076	0.87286	0.87493	0.87698	0.879	0.881	0.88298
1.2	0.88493	0.88686	0.88877	0.89065	0.89251	0.89435	0.89617	0.89796	0.89973	0.90147
1.3	0.9032	0.9049	0.90658	0.90824	0.90988	0.91149	0.91309	0.91466	0.91621	0.91774
1.4	0.91924	0.92073	0.9222	0.92364	0.92507	0.92647	0.92785	0.92922	0.93056	0.93189
1.5	0.93319	0.93448	0.93574	0.93699	0.93822	0.93943	0.94062	0.94179	0.94295	0.94408
1.6	0.9452	0.9463	0.94738	0.94845	0.9495	0.95053	0.95154	0.95254	0.95352	0.95449
1.7	0.95543	0.95637	0.95728	0.95818	0.95907	0.95994	0.9608	0.96164	0.96246	0.96327
1.8	0.96407	0.96485	0.96562	0.96638	0.96712	0.96784	0.96856	0.96926	0.96995	0.97062
1.9	0.97128	0.97193	0.97257	0.9732	0.97381	0.97441	0.975	0.97558	0.97615	0.9767
2.0	0.97725	0.97778	0.97831	0.97882	0.97932	0.97982	0.9803	0.98077	0.98124	0.98169
2.1	0.98214	0.98257	0.983	0.98341	0.98382	0.98422	0.98461	0.985	0.98537	0.98574
2.2	0.9861	0.98645	0.98679	0.98713	0.98745	0.98778	0.98809	0.9884	0.9887	0.98899
2.3	0.98928	0.98956	0.98983	0.9901	0.99036	0.99061	0.99086	0.99111	0.99134	0.99158
2.4	0.9918	0.99202	0.99224	0.99245	0.99266	0.99286	0.99305	0.99324	0.99343	0.99361
2.5	0.99379	0.99396	0.99413	0.9943	0.99446	0.99461	0.99477	0.99492	0.99506	0.9952
2.6	0.99534	0.99547	0.9956	0.99573	0.99585	0.99598	0.99609	0.99621	0.99632	0.99643
2.7	0.99653	0.99664	0.99674	0.99683	0.99693	0.99702	0.99711	0.9972	0.99728	0.99736
2.8	0.99744	0.99752	0.9976	0.99767	0.99774	0.99781	0.99788	0.99795	0.99801	0.99807
2.9	0.99813	0.99819	0.99825	0.99831	0.99836	0.99841	0.99846	0.99851	0.99856	0.99861
3.0	0.99865	0.99869	0.99874	0.99878	0.99882	0.99886	0.99889	0.99893	0.99896	0.999
3.1	0.99903	0.99906	0.9991	0.99913	0.99916	0.99918	0.99921	0.99924	0.99926	0.99929
3.2	0.99931	0.99934	0.99936	0.99938	0.9994	0.99942	0.99944	0.99946	0.99948	0.9995
3.3	0.99952	0.99953	0.99955	0.99957	0.99958	0.9996	0.99961	0.99962	0.99964	0.99965
3.4	0.99966	0.99968	0.99969	0.9997	0.99971	0.99972	0.99973	0.99974	0.99975	0.99976
3.5	0.99977	0.99978	0.99978	0.99979	0.9998	0.99981	0.99981	0.99982	0.99983	0.99983
3.6	0.99984	0.99985	0.99985	0.99986	0.99986	0.99987	0.99987	0.99988	0.99988	0.99989
3.7	0.99989	0.9999	0.9999	0.9999	0.99991	0.99991	0.99992	0.99992	0.99992	0.99992
3.8	0.99993	0.99993	0.99993	0.99994	0.99994	0.99994	0.99994	0.99995	0.99995	0.99995
3.9	0.99995	0.99995	0.99996	0.99996	0.99996	0.99996	0.99996	0.99996	0.99997	0.99997

How to use a Z Table

A z-table, also called standard normal table, is a table used to find the percentage of values below a given z-score in a standard normal distribution.

A z-score, also known as standard score, indicates how many standard deviations away a data point is above (or below) the mean. A positive z-score implies that the data point is above the mean, while a negative z-score indicates that the data point falls below the mean.

It is calculated with the following formula: 𝑧 = (𝑋 − 𝜇) ⁄ 𝜎 (where 𝑋 is the data point, 𝜇 is the population mean, and 𝜎 is the population standard deviation). A z-score is basically a standardized variable that has been rescaled to have a mean µ of 0 and a standard deviation σ of 1 (which ultimately provides a standard set of z-values - from the z-table - that can be used for easy calculations).

How to read a Z Table

Check the sign of your z-score. If it's negative, use a negative z-score table. If it's positive, use a positive z-score table.
Split the z-score into two parts. The first part goes up to the first digit after the decimal (i.e. 2.34 → 2.3). The second part is made up of the remaining digit (i.e. 2.34 → 0.04).
Look at the leftmost column of the table and find the row that matches the first part of your z-score (e.g. 2.3).
Look at the topmost row of the table and find the column that matches the second part of your z-score (e.g. 0.04).
The intersection between the column and the row corresponds to the p-value. For a z-score of 2.34, the p-value is 0.99036 (or 99.036%).

Example 1

Suppose the scores on a college exam are normally distributed with a mean 𝜇 of 70 and a standard deviation 𝜎 of 4. What is the z-score of the value 75? In other words, what proportion of students scored less than 75 points?

Compute the z-score: 𝑧 = (75 - 70) / 4 = 1.25 (this result means that a score of 75 points is 1.25 standard deviations above from the mean).
Since the z-score is positive, look for the value 1.25 in the positive z-table: 0.89435 (89.435% of the students scored less than 75 points).

Example 2

Following the previous example (𝜇 = 70 and 𝜎 = 4), what proportion of students scored more than 64 points?

Compute the z-score: 𝑧 = (64 - 70) / 4 = -1.5 (this result means that a score of 64 points is 1.5 standard deviations below the mean).
Since the z-score is negative, look for the value -1.5 in the negative z-table: 0.06681 (or 6.681%).
At this point, we've obtained the proportion of students who scored less than 64 points (P(Z < -1.5) = 0.06681), but since we want to know the proportion of those who scored more than 64 points, we just need to calculate the complement of P(Z < -1.5): 1 - P(Z < -1.5) = 1 - 0.06681 = 0.93319 (93.319%).

Example 3

Still following the same example (𝜇 = 70 and 𝜎 = 4), what proportion of students scored between 68 and 73 points?

Compute the first z-score: 𝑧 = (68 - 70) / 4 = -0.5.
Compute the second z-score: 𝑧 = (73 - 70) / 4 = 0.75.
Look for the value -0.5 in the negative z-table: 0.30854
Look for the value 0.75 in the positive z-table: 0.77337
The proportion of students who scored between 68 and 73 points is: P(68 < X < 73) = P(-0.5 < Z < 0.75) = P(Z < 0.75) - P(Z < -0.5) = 0.46483 (46.483%).

Example 4

What score corresponds to the 90th percentile? In other words, what is the data point 𝑋 for which we get a p-value of 0.9?

Find a z-score that is the closest of the p-value 0.9: z = 1.28 (with a p-value of 0.89973).
Compute 𝑋: 𝑋 = 𝜇 + 𝑧𝜎. 𝑋 ≈ 70 + (1.28 x 4) = 75.12.

Z-Score Table (Standard Normal Table)