LTE Throughput Calculator

Q: How do you calculate LTE throughput?

Multiply resource elements by bits each carries: TP = N_PRB x 168 x Qm x code-rate x layers x 1000. For 20 MHz, 64-QAM, 2 layers this is about 150 Mbps.

Q: How many PRBs are in 20 MHz LTE?

20 MHz LTE has 100 PRBs. 1.4 MHz=6, 3=15, 5=25, 10=50, 15=75, 20=100.

Q: What gives LTE Cat-4 150 Mbps?

20 MHz with 64-QAM and 2x2 MIMO gives about 150 Mbps, the Category-4 downlink peak.

Q: Why is real LTE speed lower than the peak?

The peak assumes best modulation, full allocation and no retransmissions. Real links lose ~25% to overhead, use lower modulation at the edge, and share capacity.

Channel bandwidth

Modulation

MIMO layers

Code rate (0–1)

Overhead (control + reference signals)

A physical-layer estimate (normal CP, 14 OFDM symbols/ms). Real throughput also depends on scheduling, HARQ retransmissions and SINR. 20 MHz + 64-QAM + 2×2 at 0% overhead ≈ the famous Cat-4 150 Mbps.

How it worksThe throughput formula

LTE carries data on resource elements (REs). Each Physical Resource Block (PRB) is 12 subcarriers × 14 OFDM symbols = 168 REs per 1 ms subframe. Throughput is the number of REs times the bits each one carries:

TP (bps) = N_PRB × 168 × Q_m × R × layers × 1000 × (1 − overhead)

N_PRB: 6 / 15 / 25 / 50 / 75 / 100 (1.4–20 MHz)
Q_m: QPSK 2 · 16QAM 4 · 64QAM 6 · 256QAM 8 1000 = subframes/s

The ×1000 converts per-subframe (1 ms) to per-second. The overhead term removes resources used by reference signals, PDCCH/PHICH and synchronisation — roughly a quarter of REs in practice. The published UE-category peaks (Cat-4 150 Mbps, Cat-6 300 Mbps with carrier aggregation, Cat-16 ~1 Gbps) come from the TBS tables, which this formula approximates closely at 0% overhead.

FAQFrequently asked questions

How do you calculate LTE throughput?

Multiply resource elements by the bits each carries: TP = N_PRB × 168 × Q_m × code-rate × layers × 1000. For 20 MHz (100 PRB), 64-QAM (6), R≈0.75, 2 layers that is about 150 Mbps.

How many PRBs are in 20 MHz LTE?

100 PRBs. The mapping is 1.4 MHz = 6, 3 MHz = 15, 5 MHz = 25, 10 MHz = 50, 15 MHz = 75 and 20 MHz = 100 PRBs.

What gives LTE Cat-4 150 Mbps?

20 MHz bandwidth with 64-QAM and 2×2 MIMO. At the physical-layer peak that is ~150 Mbps, which is the Category-4 downlink limit.

Why is real LTE speed lower than the peak?

The peak assumes the best modulation, full PRB allocation and no retransmissions. Real links lose ~25% of REs to control and reference signals, plus lower modulation at cell edge, HARQ retransmissions and shared scheduling.

How it worksThe throughput formula

FAQFrequently asked questions

RelatedMore engineering tools