NTPsec

ntp2.sebi.org

Report generated: Tue Jun 23 18:53:00 2026 UTC
Start Time: Mon Jun 22 18:53:00 2026 UTC
End Time: Tue Jun 23 18:53:00 2026 UTC
Report Period: 1.0 days

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Local Clock Time/Frequency Offsets

local offset plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Time Offset -319.845 -319.845 -303.576 45.018 774.216 858.779 858.779 1,077.792 1,178.624 287.496 83.262 µs 0.8555 3.401
Local Clock Frequency Offset 50.181 50.181 50.183 50.295 50.366 50.367 50.367 0.183 0.185 0.047 50.294 ppm -0.8448 3.924

The time and frequency offsets between the ntpd calculated time and the local system clock. Showing frequency offset (red, in parts per million, scale on right) and the time offset (blue, in μs, scale on left). Quick changes in time offset will lead to larger frequency offsets.

These are fields 3 (time) and 4 (frequency) from the loopstats log file.



Local RMS Time Jitter

local jitter plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Time Jitter 71.575 71.575 85.036 161.465 195.817 198.465 198.465 110.781 126.890 32.529 153.564 µs -0.8557 2.848

The RMS Jitter of the local clock offset. In other words, how fast the local clock offset is changing.

Lower is better. An ideal system would be a horizontal line at 0μs.

RMS jitter is field 5 in the loopstats log file.



Local RMS Frequency Jitter

local stability plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Frequency Jitter 1.477 1.477 1.752 9.097 31.226 35.585 35.585 29.474 34.108 9.015 11.515 ppb 0.9655 3.105

The RMS Frequency Jitter (aka wander) of the local clock's frequency. In other words, how fast the local clock changes frequency.

Lower is better. An ideal clock would be a horizontal line at 0ppm.

RMS Frequency Jitter is field 6 in the loopstats log file.



Local Clock Time Offset Histogram

local offset histogram plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Offset -319.845 -319.845 -303.576 45.018 774.216 858.779 858.779 1,077.792 1,178.624 287.496 83.262 µs 0.8555 3.401

The clock offsets of the local clock as a histogram.

The Local Clock Offset is field 3 from the loopstats log file.



Server Offsets

peer offsets plot

The offset of all refclocks and servers. This can be useful to see if offset changes are happening in a single clock or all clocks together.

Clock Offset is field 5 in the peerstats log file.



Server Offset 131.188.3.221

peer offset 131.188.3.221 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 131.188.3.221 -335.343 -335.343 -323.267 48.728 751.333 778.996 778.996 1,074.600 1,114.339 291.073 77.972 µs 0.7116 3.081

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 185.131.196.23

peer offset 185.131.196.23 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 185.131.196.23 -0.126 -0.126 -0.081 0.311 1.018 1.093 1.093 1.100 1.219 0.303 0.342 ms 0.79 3.08

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 192.53.103.104

peer offset 192.53.103.104 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 192.53.103.104 -316.213 -316.213 -306.699 140.085 828.743 885.204 885.204 1,135.442 1,201.417 297.316 152.259 µs 0.6161 3.072

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 193.79.237.14

peer offset 193.79.237.14 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 193.79.237.14 -936.584 -936.584 -890.223 -512.636 -13.974 167.129 167.129 876.249 1,103.713 268.786 -473.707 µs 0.4213 2.664

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 2001:628:2030:dcf1::ac0 (ts1.aco.net)

peer offset 2001:628:2030:dcf1::ac0 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:628:2030:dcf1::ac0 (ts1.aco.net) -275.711 -275.711 -257.398 130.049 828.351 856.374 856.374 1,085.749 1,132.085 300.181 158.334 µs 0.6871 2.885

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de)

peer offset 2001:638:a000:1123:123::1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) -399.830 -399.830 -367.051 -9.200 680.694 736.991 736.991 1,047.745 1,136.821 288.532 25.907 µs 0.7073 2.96

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de)

peer offset 2a01:4f8:0:a112::2:2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) -1.429 -1.429 -1.083 -0.037 1.034 1.289 1.289 2.117 2.718 0.556 0.050 ms 0.06383 3.681

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Jitters

peer jitters plot

The RMS Jitter of all refclocks and servers. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 131.188.3.221

peer jitter 131.188.3.221 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 131.188.3.221 29.719 29.719 35.994 150.365 377.765 471.803 471.803 341.771 442.084 107.980 170.420 µs 0.8322 2.918

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 185.131.196.23

peer jitter 185.131.196.23 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 185.131.196.23 33.663 33.663 71.156 198.458 519.950 571.182 571.182 448.794 537.519 134.368 225.372 µs 0.8557 2.876

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 192.53.103.104

peer jitter 192.53.103.104 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 192.53.103.104 40.617 40.617 57.496 144.546 358.663 445.716 445.716 301.167 405.099 95.618 172.052 µs 0.7795 2.826

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 193.79.237.14

peer jitter 193.79.237.14 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 193.79.237.14 0.000 0.000 15.812 117.494 552.114 637.824 637.824 536.302 637.824 162.546 178.673 µs 1.339 3.862

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 2001:628:2030:dcf1::ac0 (ts1.aco.net)

peer jitter 2001:628:2030:dcf1::ac0 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:628:2030:dcf1::ac0 (ts1.aco.net) 40.694 40.694 46.618 132.497 438.906 457.103 457.103 392.288 416.409 108.154 165.297 µs 1.228 3.72

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de)

peer jitter 2001:638:a000:1123:123::1 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) 24.682 24.682 31.425 152.777 381.448 402.196 402.196 350.023 377.514 100.785 167.918 µs 0.7136 2.817

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de)

peer jitter 2a01:4f8:0:a112::2:2 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) 0.036 0.036 0.062 0.281 1.054 1.414 1.414 0.992 1.377 0.347 0.430 ms 0.9784 2.854

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset 50.181 50.181 50.183 50.295 50.366 50.367 50.367 0.183 0.185 0.047 50.294 ppm -0.8448 3.924
Local Clock Time Offset -319.845 -319.845 -303.576 45.018 774.216 858.779 858.779 1,077.792 1,178.624 287.496 83.262 µs 0.8555 3.401
Local RMS Frequency Jitter 1.477 1.477 1.752 9.097 31.226 35.585 35.585 29.474 34.108 9.015 11.515 ppb 0.9655 3.105
Local RMS Time Jitter 71.575 71.575 85.036 161.465 195.817 198.465 198.465 110.781 126.890 32.529 153.564 µs -0.8557 2.848
Server Jitter 131.188.3.221 29.719 29.719 35.994 150.365 377.765 471.803 471.803 341.771 442.084 107.980 170.420 µs 0.8322 2.918
Server Jitter 185.131.196.23 33.663 33.663 71.156 198.458 519.950 571.182 571.182 448.794 537.519 134.368 225.372 µs 0.8557 2.876
Server Jitter 192.53.103.104 40.617 40.617 57.496 144.546 358.663 445.716 445.716 301.167 405.099 95.618 172.052 µs 0.7795 2.826
Server Jitter 193.79.237.14 0.000 0.000 15.812 117.494 552.114 637.824 637.824 536.302 637.824 162.546 178.673 µs 1.339 3.862
Server Jitter 2001:628:2030:dcf1::ac0 (ts1.aco.net) 40.694 40.694 46.618 132.497 438.906 457.103 457.103 392.288 416.409 108.154 165.297 µs 1.228 3.72
Server Jitter 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) 24.682 24.682 31.425 152.777 381.448 402.196 402.196 350.023 377.514 100.785 167.918 µs 0.7136 2.817
Server Jitter 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) 0.036 0.036 0.062 0.281 1.054 1.414 1.414 0.992 1.377 0.347 0.430 ms 0.9784 2.854
Server Offset 131.188.3.221 -335.343 -335.343 -323.267 48.728 751.333 778.996 778.996 1,074.600 1,114.339 291.073 77.972 µs 0.7116 3.081
Server Offset 185.131.196.23 -0.126 -0.126 -0.081 0.311 1.018 1.093 1.093 1.100 1.219 0.303 0.342 ms 0.79 3.08
Server Offset 192.53.103.104 -316.213 -316.213 -306.699 140.085 828.743 885.204 885.204 1,135.442 1,201.417 297.316 152.259 µs 0.6161 3.072
Server Offset 193.79.237.14 -936.584 -936.584 -890.223 -512.636 -13.974 167.129 167.129 876.249 1,103.713 268.786 -473.707 µs 0.4213 2.664
Server Offset 2001:628:2030:dcf1::ac0 (ts1.aco.net) -275.711 -275.711 -257.398 130.049 828.351 856.374 856.374 1,085.749 1,132.085 300.181 158.334 µs 0.6871 2.885
Server Offset 2001:638:a000:1123:123::1 (ntp0.rrze.ipv6.uni-erlangen.de) -399.830 -399.830 -367.051 -9.200 680.694 736.991 736.991 1,047.745 1,136.821 288.532 25.907 µs 0.7073 2.96
Server Offset 2a01:4f8:0:a112::2:2 (ntp2.hetzner.de) -1.429 -1.429 -1.083 -0.037 1.034 1.289 1.289 2.117 2.718 0.556 0.050 ms 0.06383 3.681
Summary as CSV file


Glossary:

frequency offset:
The difference between the ntpd calculated frequency and the local system clock frequency (usually in parts per million, ppm)
jitter, dispersion:
The short term change in a value. NTP measures Local Time Jitter, Refclock Jitter, and Server Jitter in seconds. Local Frequency Jitter is in ppm or ppb.
ms, millisecond:
One thousandth of a second = 0.001 seconds, 1e-3 seconds
mu, mean:
The arithmetic mean: the sum of all the values divided by the number of values. The formula for mu is: "mu = (∑xi) / N". Where xi denotes the data points and N is the number of data points.
ns, nanosecond:
One billionth of a second, also one thousandth of a microsecond, 0.000000001 seconds and 1e-9 seconds.
percentile:
The value below which a given percentage of values fall.
ppb, parts per billion:
Ratio between two values. These following are all the same: 1 ppb, one in one billion, 1/1,000,000,000, 0.000,000,001, 1e-9 and 0.000,000,1%
ppm, parts per million:
Ratio between two values. These following are all the same: 1 ppm, one in one million, 1/1,000,000, 0.000,001, and 0.000,1%
‰, parts per thousand:
Ratio between two values. These following are all the same: 1 ‰. one in one thousand, 1/1,000, 0.001, and 0.1%
refclock:
Reference clock, a local GPS module or other local source of time.
remote clock:
Any clock reached over the network, LAN or WAN. Also called a peer or server.
time offset:
The difference between the ntpd calculated time and the local system clock's time. Also called phase offset.
σ, sigma:
Sigma denotes the standard deviation (SD) and is centered on the arithmetic mean of the data set. The SD is simply the square root of the variance of the data set. Two sigma is simply twice the standard deviation. Three sigma is three times sigma. Smaller is better.
The formula for sigma is: "σ = √[ ∑(xi-mu)^2 / N ]". Where xi denotes the data points and N is the number of data points.
Skewness, Skew:
The skewness of a random variable X is the third standardized moment and is a dimension-less ratio. ntpviz uses the FIsher-Pearson moment of skewness. There are other different ways to calculate Skewness Wikipedia describes Skewness best: "The qualitative interpretation of the skew is complicated and unintuitive."
A normal distribution has a skewness of zero.
Kurtosis, Kurt:
The kurtosis of a random variable X is the fourth standardized moment and is a dimension-less ratio. ntpviz uses standard Kurtosis. There are other different ways to calculate Kurtosis.
A normal distribution has a Kurtosis of three. NIST describes a kurtosis over three as "heavy tailed" and one under three as "light tailed".
upstream clock:
Any server or reference clock used as a source of time.
µs, us, microsecond:
One millionth of a second, also one thousandth of a millisecond, 0.000,001 seconds, and 1e-6 seconds.



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