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5G Throughput Calculation: Step-by-Step

Throughput is one of the most critical KPIs in 5G networks. It determines the actual data rate a user experiences, which is influenced by several network parameters such as bandwidth, subcarrier spacing, MIMO layers, modulation scheme, and coding rate.

In this article, we will walk through the 5G NR throughput calculation step by step, providing a detailed explanation of each component.


What is Throughput in 5G?

Throughput in 5G refers to the rate at which data is successfully transmitted over a communication channel. It is usually measured in Mbps or Gbps.

There are two types:

  • Theoretical Throughput: Maximum data rate based on system configuration.

  • User-perceived Throughput: The actual rate experienced by the end-user.


Parameters in Throughput Calculation


Parameter

Description

Bandwidth (BW)

Total allocated spectrum (e.g., 100 MHz)

Subcarrier Spacing (SCS)

Distance between two subcarriers (e.g., 15, 30, 60, 120 kHz)

Modulation Scheme

Number of bits per symbol (e.g., QPSK=2, 16QAM=4, 64QAM=6, 256QAM=8)

Code Rate (CR)

Efficiency of FEC coding (value between 0.0 to 1.0)

Number of Resource Blocks (NRB)

Depends on BW and SCS as per 3GPP TS 38.104

Symbols per Slot

Usually 14 symbols per slot (normal CP)

Slots per Subframe

Depends on SCS. E.g., SCS=30kHz ⇒ 2 slots/subframe

Number of Antenna Layers

MIMO layers used (e.g., 2x2, 4x4 MIMO)


Throughput Calculation Formula

Throughput=NRB×12×Modulation Order×Code Rate×Symbols per Slot×Slots per Second×Number of Layers

 

Where:

  • 12 is the number of subcarriers per RB

  • N_RB = Number of Resource Blocks

  • Modulation Order = Number of bits per symbol (QPSK=2, 16QAM=4, etc.)

  • Code Rate = 0.93 (for max MCS index 27)

  • Symbols per Slot = 14 (normal CP)

  • Slots/sec = Depends on SCS

  • Layers = MIMO layers used


As per 3gpp 38.306 – 4.1.2

38.306 – 4.1.2
reference - 38.306 – 4.1.2 3gpp

Slots per Second Based on SCS

SCS (kHz)

Slot Duration (ms)

Slots/sec

15

1

1000

30

0.5

2000

60

0.25

4000

120

0.125

8000

 

To understand above table lets take an example for SCS = 30 kHz

Slot Duration=1 ms/SCS Factor =1ms/ (30/15)

=0.5 ms

Slots/sec = 1000 ms/sec/(0.5 ms) = 2000 Slots /sec

 

Resource Block Count (NRB) vs Bandwidth

As per 3GPP TS 38.104, the number of Resource Blocks (NRB) depends on:

  • The channel bandwidth (in MHz)

  • The Subcarrier Spacing (SCS)

  • Inclusion of guard bands and FFT alignment

Let’s determine the number of RBs for a 100 MHz channel bandwidth using 30 kHz SCS.

  • From 3GPP TS 38.104, for 100 MHz at 30 kHz SCS:

NRB =273


This includes guard bands and aligns with FFT requirements for 5G NR

 

Bandwidth (MHz)

NRB @ 30kHz SCS

5

11

10

24

20

51

40

106

100

273

 

 

For 100 MHz bandwidth with 30 kHz SCS, the number of Resource Blocks (NRB) = 273.

 

Let's calculate the throughput for the following configuration:

  • Bandwidth = 100 MHz

  • SCS = 30 kHz

  • Modulation = 256-QAM (8 bits/symbol)

  • Code Rate = 0.93

  • MIMO Layers = 4 (i.e., 4x4)

  • NRB = 273 (from 3GPP for 100 MHz @ 30 kHz SCS)

  • Symbols/Slot = 14 (excluding DMRS and control overhead for simplicity)

  • Slots/sec = 2000 (for 30 kHz SCS)

 

Put the above values in formula

Throughput=NRB×12×Modulation Order×Code Rate×Symbols per Slot×Slots per Second×Number of Layers

=273×12×8×0.93×14×2000×4

=3286×8×0.93×14×2000×4

=26208 bits/symbol × 0.93×14×2000×4

=24373.44×14×2000×4

=341288.16×2000×4

=682456320×4

=2729825280 bits/sec

 

Now convert into Mbps and Gbps

=2729825280 /10^6

=2729.83 Mbps

=2.73 Gbps


If you apply 14% overhead, the adjusted usable throughput is:

=2729.83× (1−0.14) =2347.35 Mbps =2.35 Gbps


Real-world throughput is slightly less than theoretical due to:

  • Control signalling (DCI, RRC, MAC)

  • Reference signals (DMRS, CSI-RS)

  • HARQ, retransmissions

  • Guard bands and scheduling inefficiencies


Typically, ~80–90% of theoretical throughput is achieved in practice.

 

Similar manner if we want to calculate for different value below is the calculation

Parameter

Case 1

Case 2

Bandwidth

100 MHz

20 MHz

SCS

30 kHz

30 kHz

Modulation

256-QAM (8 bits)

64-QAM (6 bits)

MIMO Layers

4

2

Code Rate

0.93

0.8

Symbols per Slot

14

14

Slots/sec

2000

2000

NRB

273

51

Calculated Throughput

2.73 Gbps

~137 Mbps

 

Throughput calculation in 5G is a vital metric that helps network planners and engineers estimate data capacity and user experience. By understanding each parameter—RBs, modulation, code rate, symbols, and layers—you can estimate peak and realistic throughput levels under different scenarios.
Whether you're planning 5G deployments, optimizing UE performance, or testing KPIs, this knowledge will enable precise performance estimation aligned with 3GPP specifications.

 

References

  • 3GPP TS 38.306 – Defines max modulation, MIMO layers, and code rates for UE capability.

  • 3GPP TS 38.101-1 – Lists NRB values for different bandwidths and SCS configurations.

  • 3GPP TS 38.211 – Describes physical channels, modulation, and resource grid structure.

  • 3GPP TS 38.213 – Covers control overheads like PDCCH, DMRS, and TDD slot configuration.

  • 3GPP TS 38.104 – Specifies the maximum number of PRBs for a given bandwidth/SCS.

  • 3GPP TS 38.300 – Provides overall 5G NR architecture, slot structure, and services.

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