Throughput Calculator
An interactive 5G/LTE peak-throughput estimator — set PRBs, numerology, MIMO layers, modulation, code rate and overhead and read the rate live.
Set the carrier, the TDD pattern and the modulation, and read the peak downlink and uplink throughput live. Bandwidth and numerology auto-resolve the resource-block count; the TDD slot pattern splits the rate between DL and UL. Hover the i on any field for an explanation. Grounded in the 3GPP TS 38.306 approximate data-rate formula.
Calculator
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Switch Duplex to FDD and the TDD rows disappear — DL and UL each get the full carrier. In TDD the DL/UL split follows the pattern; toggle Count special slot to include or exclude the special slot's DL/UL symbols. Pick a preset or set Custom and enter your own slot counts.
How the Numbers Are Formed
The peak rate in one direction is the full-carrier rate times the fraction of time that direction gets. The full-carrier rate is the TS 38.306 approximate formula:
N_PRB comes from the bandwidth and SCS (auto-resolved from the 38.101 tables); Q_m is bits per symbol; f is the code rate; R_max = 948/1024; the bracket is resource elements per second (12 subcarriers per RB × 14 symbols/slot × 2μ slots/ms × 1000 ms); and (1 − OH) removes control/RS overhead.
Then the direction fraction:
TDD: DL fraction = ( NDL + Nspecial · SDL/14 ) ÷ Nperiod | UL fraction = ( NUL + Nspecial · SUL/14 ) ÷ Nperiod
where N_period = DL + UL + special slots in the pattern, and S_DL/S_UL are the DL/UL OFDM symbols inside the special slot. Unchecking Count special slot drops the S/14 terms (treats the whole special slot as guard).
TDD Patterns and the Special Slot
In TDD, DL and UL share the carrier in time, so the DL:UL throughput ratio is set by the slot pattern. The common presets:
| Pattern | Period | DL : special : UL | Typical use |
|---|---|---|---|
DDDSU | 5 slots (2.5 ms @ 30 kHz) | 3 D : 1 S : 1 U | Common DL-heavy TDD (default) |
DDDDDDDSUU | 10 slots (5 ms @ 30 kHz) | 7 D : 1 S : 2 U | Very DL-heavy |
DDDSUDDSUU | 10 slots (5 ms) | 5 D : 2 S : 3 U | More balanced |
DSUUU | 5 slots | 1 D : 1 S : 3 U | UL-heavy (industrial/upload) |
The special slot (S) sits between a downlink and an uplink slot to give the UE time to switch from receiving to transmitting. It is split into some DL symbols, a guard period, and some UL symbols — a typical SCS-30 kHz split is 10 DL : 2 guard : 2 UL. Those DL and UL symbols do carry data (PDSCH in the DL part, PUCCH/PUSCH in the UL part), which is why the calculator lets you count them. Excluding them gives the conservative "whole-slot only" figure.
Reading DL vs UL
The two big numbers are the crisp answer: Downlink peak and Uplink peak, each already scaled by that direction's share of the frame. The note under the results shows the DL% / UL% split so you can see where the asymmetry comes from. For a DL-heavy pattern like DDDSU the downlink dwarfs the uplink; for DSUUU the uplink wins. FDD removes the split entirely — both directions run at the full-carrier rate because they use separate paired spectrum. For carrier aggregation, compute one component carrier and multiply by the number of carriers.
What This Captures
These are peak figures: every RB scheduled, at the chosen modulation/code rate, on every layer. Real cell throughput is lower — the scheduler shares the cell, the channel forces lower MCS at range, HARQ retransmissions cost capacity, and the special slot's guard period is pure overhead. Lower the modulation and layers to match a reported CQI/rank for a realistic single-UE estimate. The bandwidth→PRB mapping follows TS 38.101-1 (FR1) and 38.101-2 (FR2); a blank result means that bandwidth is not defined for the chosen SCS.
Q. Why is my uplink so much lower than downlink?
A. Two reasons stack: TDD gives the uplink fewer slots (e.g. only 1 of 5 in DDDSU), and UEs usually transmit with fewer layers and lower-order modulation than the gNB sends. Switch to FDD or a UL-heavy pattern like DSUUU and the uplink rises sharply.
Q. Does counting the special slot matter much?
A. It can add ~10–15% to the DL figure, because the special slot's DL symbols (often 10 of 14) are real PDSCH. Excluding it is the safe floor; including it is closer to what a good scheduler actually achieves.
Q. Why does the PRB count change when I change SCS?
A. A fixed bandwidth holds fewer, wider resource blocks at a higher SCS (each RB is 12 subcarriers, so it gets wider). 100 MHz is 273 PRB at 30 kHz but 135 PRB at 60 kHz — the calculator resolves this from the 38.101 tables automatically.
Go deeper
The theory and the other calculators.