A live Black-Scholes options calculator — theoretical price, the full Greeks, and a Theta Decay Meter that shows exactly how fast this contract is bleeding time value as expiration approaches.
This is the contract's extrinsic (time) value if everything else holds constant, plotted from today's days-to-expiration down to zero at expiry. Decay isn't linear — it accelerates hardest in the final couple of weeks, which is exactly what the gauge above is tracking in real time as you adjust days to expiration.