How credits work

Credits are your account balance for running on real quantum hardware: what is free, what a hardware run costs, and how you approve it before spending.

Credits are a balance on your account. You spend them to run on real quantum hardware, and nothing else on Qollab costs credits.

What is free

Every simulator is free, both the ones that run locally in your browser and the ones that run remotely on IonQ's cloud. You can write, run, and publish an entire project without spending a credit. Compute backends shows which backends are simulators and which are hardware.

What a run costs

Only the quantum computer backends spend credits, and the runner caps what a single run can spend without asking. It carries an editable allowance, shown as Allow running if it doesn't exceed N credits, which starts at a tenth of your balance. A run priced under that allowance proceeds without stopping to ask. A run priced above it stops and asks you to confirm, showing the cost next to your balance, and declining spends nothing.

The amount depends on your circuit and how many shots you run. On hardware the quoted figure is an estimate; once the job finishes, the runner shows the actual credits withdrawn, which can differ from the estimate. Simulators report a cost of zero and run for free.

What drives IonQ's cost

The figure the runner quotes has two layers behind it: IonQ charges for the job that runs on their machine, and Qollab charges credits from your balance. IonQ publishes how the first layer is sized, which explains why one hardware run costs IonQ more than another. It is not the calculation behind your credit charge, and the two figures do not convert into each other.

IonQ is explicit about that limit: their published pricing model covers direct access to their commercially available quantum computers, and they say it may not apply directly to anyone reaching those systems through a partner, whose own documentation applies instead. Qollab is that partner.

IonQ's estimator counts the one-qubit gate operations (1Q gates) and two-qubit gate operations (2Q gates) in the circuit, then combines them with the shot count. Gates acting on three or more qubits are converted before that count is taken: an N-qubit gate is expressed as 6(N-2) two-qubit gates. A three-qubit Toffoli counts as six 2Q gates, a four-qubit gate as twelve.

One driver is absent from that description: how many qubits your circuit uses. Width is not one of the factors IonQ names, so spreading the same operations across 20 qubits instead of 5 does not by itself make the job bigger. Gates and shots are the drivers IonQ documents; their estimate endpoint also takes a qubit count as a parameter.

Why an estimate can surprise you

The gates that get counted are the ones in the compiled circuit, not the ones you wrote. IonQ's compiler decomposes multi-qubit gates, converts standard gates to its native set, and removes or relocates others. The circuit that reaches the machine can be a good deal larger or smaller than your source. IonQ says the cost for a circuit sometimes lands significantly lower or higher than their estimator predicted, based on how efficiently it transpiles and optimises.

That is the usual reason a run prices differently from the gate count on your screen. It is also why the runner treats its quoted figure as an estimate and reports the actual credits withdrawn afterwards. How your circuit is compiled covers what the compiler changes.

The minimum for small jobs

In some cases IonQ applies a minimum per-circuit cost. For small jobs inside a certain size range, their charge always rounds up to that minimum, so a smaller job stops getting cheaper. Above the range, their charge climbs again with gates and shots.

Both the size threshold and the minimum move with debiasing, IonQ's built-in error mitigation. Both are lower when debiasing is off, so switching it off can lower IonQ's charge for a job in that range, while larger jobs are unaffected either way. Debiasing is enabled by default at 500 shots or more and cannot run below that, and the backend default of 1024 clears the floor. Error mitigation and debiasing covers the floor and how to turn it off.

Keeping costs down

  • Simulate first. Get the circuit right on a free simulator before spending anything. Compute backends lists which backends are free.
  • Start with fewer shots. Shots drive the cost, so keep the first hardware run's shot count modest while you confirm the circuit behaves on a real device.
  • Lower the allowance. The runner's Allow running if it doesn't exceed field is editable; set it low and every hardware run above that figure stops to ask before it charges. The field lives in the runner, not in your profile settings, and it is remembered per project.

Your balance

Your credit balance lives in your profile settings. The runner reads it before every hardware run. If a run would cost more than you have, it links you to where to get more.

Getting credits

The way to earn credits today is the Qollab Grant Program: port, fork, or publish open-source quantum work on Qollab, and get compute credits for it. The award amounts, and how those credits are issued and expire, live on the program page and its terms.

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