NTP (Network Time Protocol) Clock Offset (θ) & Round-Trip Delay (δ) Calculator

Compute RFC 5905 NTP clock skew offset θ (ms) and network round-trip path delay δ (ms).

NTP Clock Offset (θ)
12 ms
Net Network Round-Trip Delay (δ) 60 ms
One-Way Symmetric Path Delay (δ / 2) 30 ms
Server Residence / Processing Time (t₃ − t₂) 2 ms
Inputs
⚡ Scenarios:
ms
Client request origin timestamp t₁ (ms).
ms
Server request receive timestamp t₂ (ms).
ms
Server response transmit timestamp t₃ (ms).
ms
Client response arrival timestamp t₄ (ms).
Results & Graph
NTP Clock Offset (θ)
12 ms
Net Network Round-Trip Delay (δ)
60 ms
One-Way Symmetric Path Delay (δ / 2)
30 ms
Server Residence / Processing Time (t₃ − t₂)
2 ms

NTP Clock Offset (θ)

Graph 1 • NTP Clock Offset & Delay • Domain Architecture & Live Telemetry Maps Client Transmit T1 Ms, Server Receive T2 Ms, Server Transmit T3 Ms through NTP Clock Offset & Delay Formula.
BROADCAST, NETWORK & DEVOP NTP Clock Offset (θ) 12 ms Net Network Round-Trip Del 60 ms NTP Clock Offset & Delay • Component Waterfall NTP Clock Offset (θ) 12 ms Net Network Round-Trip Delay ( 60 ms One-Way Symmetric Path Delay ( 30 ms Server Residence / Processing 2 ms
Graph 2 • NTP Clock Offset (θ) Across Client Transmit T1 Ms Sweep (40% → 160%) Evaluates Offset θ = [ (t₂ − t₁) + (t₃ − t₄) ] / 2; RoundTripDelay δ = (t₄ − t₁) across 7 operating points (current input highlighted).
-288 ms 27.60 ms 343.2 ms 312 400ms 212 600ms 112 800ms 12 1.0kms -88 1.2kms -188 1.4kms -288 1.6kms
Graph 3 • Joint Sensitivity: Client Transmit T1 Ms × Server Receive T2 Ms Compares NTP Clock Offset (θ) when Server Receive T2 Ms is shifted +25% (solid) vs. −25% (dashed).
-268.3 ms 26.75 ms 321.8 ms --- Server Receive T2 Ms @ 75% 292.5 -30% 217.5 -15% 142.5 +0% 67.50 +15% -7.50 +30%
Summary: RFC 5905 NTP analysis shows the server clock is +12 ms relative to the client, with 60 ms net network round-trip delay and 2 ms server processing time.
Summary: RFC 5905 NTP analysis shows the server clock is +12 ms relative to the client, with 60 ms net network round-trip delay and 2 ms server processing time.
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Formula & Mathematical Methodology: NTP Clock Offset & Delay Formula

Offset θ = [ (t₂ − t₁) + (t₃ − t₄) ] / 2
RoundTripDelay δ = (t₄ − t₁) − (t₃ − t₂)
Offset θ = [ (t₂ − t₁) + (t₃ − t₄) ] / 2; RoundTripDelay δ = (t₄ − t₁) − (t₃ − t₂)
  • clientTransmitT1Ms: Client request origin timestamp t₁ (ms).
  • serverReceiveT2Ms: Server request receive timestamp t₂ (ms).
  • serverTransmitT3Ms: Server response transmit timestamp t₃ (ms).
  • clientReceiveT4Ms: Client response arrival timestamp t₄ (ms).

Rounding: Internal floating-point calculations run in 64-bit IEEE-754 double precision; display values round to 2–4 decimal places.

Worked Example: NTP Clock Offset & Delay Worked Example

Compute RFC 5905 NTP clock skew offset θ (ms) and network round-trip path delay δ (ms).

  1. Enter the input measurement, system configuration, or astronomical parameter.
  2. Apply the standard conversion or analytical equation: Offset θ = [ (t₂ − t₁) + (t₃ − t₄) ] / 2; RoundTripDelay δ = (t₄ − t₁) − (t₃ − t₂).
  3. Inspect the primary metric, secondary equivalents, and 3 real-time SVG graphs.
Result: Computes NTP Clock Offset & Delay via Offset θ = [ (t₂ − t₁) + (t₃ − t₄) ] / 2; RoundTripDelay δ = (t₄ − t₁) − (t₃ − t₂).

Frequently Asked Questions

How does the NTP (Network Time Protocol) Clock Offset (θ) & Round-Trip Delay (δ) Calculator perform the calculation?

It evaluates Offset θ = [ (t₂ − t₁) + (t₃ − t₄) ] / 2; RoundTripDelay δ = (t₄ − t₁) − (t₃ − t₂) directly in your browser and renders three custom SVG charts in real time.

Can I solve backwards for an input parameter using Goal Seek?

Yes. Click "🎯 Goal Seek" in the results toolbar to solve backwards for any numeric input field.

Does this tool work offline?

Yes. All calculations run 100% locally in your browser with full offline PWA support.

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NTP (Network Time Protocol) Clock Offset (θ) & Round-Trip Delay (δ) Calculator: inputs, method, and how to read the result

Compute RFC 5905 NTP clock skew offset θ (ms) and network round-trip path delay δ (ms).

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Client Transmit T1 Ms: Client request origin timestamp t₁ (ms).
  • Server Receive T2 Ms: Server request receive timestamp t₂ (ms).
  • Server Transmit T3 Ms: Server response transmit timestamp t₃ (ms).
  • Client Receive T4 Ms: Client response arrival timestamp t₄ (ms).

What the calculation includes

With the default values shown, NTP Clock Offset (θ) is 12 ms. The calculation follows NTP Clock Offset & Delay Formula; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Client Transmit T1 Ms from 1,000 ms to 1,100 ms changes NTP Clock Offset (θ) from 12 ms to -38 ms. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses official NIST Special Publication 811, IEEE/RFC systems engineering, APA psychometric, and USNO astronomical formulas.
  • Empirical metallurgy and calendar conversions represent standard reference-condition approximations.

Scope: Global NIST, IEEE, APA & Astronomical Standard Check the assumptions and limitations against your situation before relying on the estimate.

More in Dates & Time: Unit Conversion Calculator, Scientific Calculator, Date Difference & Business Days Calculator.