Every real qubit loses its quantum information over time — this is the central practical obstacle standing between today's noisy quantum hardware and useful algorithms. This simulation plots the two decay processes that actually limit a superconducting qubit: T1 energy relaxation, Pexcited(t) = exp(−t/T1), and T2 dephasing, coherence(t) = exp(−t/T2), under the real physical constraint T2 ≤ 2×T1, which the T2 slider enforces rather than allowing an unphysical value. Tune T1 and T2 to represent better or worse real hardware, set a gate-operation duration, and run the decay to see a genuine circuit-depth budget: the number of gate operations that can be reliably applied before coherence drops below a usable 50% threshold, computed directly from T2 and the gate time — not a fudged number.