Communication Latency Calculator

Signal delay from satellite altitude for LEO, MEO, and GEO.

Distance preset

Custom distance (km)

Link data rate (Mbps)

File size (MB)

Protocol overhead (%)

Tab to move between fields

One-way delay (ms)

119.37

Round-trip delay (sec)

0.24

Distance (km)35,786

One-way delay (sec)0.12

Effective throughput (Mbps)9.5

File transmit time (sec)84.21

Total transfer + RTT (sec)84.45

How to Use This Calculator

Select a distance preset (LEO, MEO, GEO, Moon, Mars) or enter a custom distance (km).
Set the communication link data rate (Mbps) and file size (MB) to transfer.
Enter protocol overhead percentage to account for TCP/IP headers and retransmissions.
Review one-way propagation delay (ms and sec), round-trip delay (sec), and effective throughput (Mbps).
Use round-trip delay to assess feasibility of real-time control — above 1 second requires autonomous operation.

What each input means

Distance preset: 0=Custom, 1=LEO 400km, 2=MEO 20,200km, 3=GEO 35,786km, 4=Moon, 5=Mars min, 6=Mars max.
Custom distance (km): Used only when preset = 0. Distance from ground station to spacecraft in km.
Link data rate (Mbps): Raw downlink or uplink data rate in megabits per second.
File size (MB): Size of data to transfer in megabytes.
Protocol overhead (%): Percentage of bandwidth consumed by framing, error correction, and protocol headers.

Distance (km): Actual distance used for the calculation.
One-way delay (ms): Light-time delay for signal to travel from transmitter to receiver.
One-way delay (sec): Same delay expressed in seconds (useful for deep-space).
Round-trip delay (sec): Time for a signal to go and return (2x one-way).
Effective throughput (Mbps): Usable data rate after protocol overhead.
File transmit time (sec): Time to send the file at the effective data rate.
Total transfer + RTT (sec): Transmit time plus one round-trip acknowledgement delay.

Identify Input Parameters
4 parameters
Distance preset = 3, Custom distance (km) = 400, Link data rate (Mbps) = 10, File size (MB) = 100 = 5 input(s) provided
Calculate One-way delay
One-way delay = oneWayDelaySec * 1000
119.369 = 119.369
Calculate Round-trip delay
Round-trip delay = 2 * oneWayDelaySec
0.239 = 0.239
Calculate Distance
35786 = 35786
Calculate One-way delay
One-way delay = distanceKm / SPEED_OF_LIGHT_KM_S
0.119 = 0.119