Idealized and realistic spines show overall trends in peak calcium, decay rates, and synaptic weight change with respect to various geometric parameters. We plotted all calcium peaks, decay time constants, and synaptic weight predictions for the various geometries against different geometric parameters including volume-to-PSD-area, volume, surface area, volume-to-surface-area ratio, and PSD-area-to-PM-area. We fitted the trends in peak values with a linear function against the geometric parameter. We fitted the decay dynamics of each calcium transient with c exp(kt) and report the decay time constant, k, as mean and SEM (n = 50) against the geometric parameter. We fitted the trend in synaptic weight change with a linear function against the geometric parameter. (a) All calcium peaks as mean and SEM (n = 50) across volume-to-PSD area ratio show no dependence. r² = 0.0152 for the linear fit. (b)r² = 0.0091 for the fit of decay time constants against volume-to-PSD area ratio. (c) Calculated synaptic weight change mean and SEM (n = 50) at the last time point for all idealized and realistic spines shows no dependence on volume-to-PSD area ratio. r² = 0.0060 for the linear fit. (d) All calcium peaks as mean and SEM (n = 50) across volume show a clear increasing trend. r² = 0.5666 for the linear fit. (e)r² = 0.1478 for the fit of decay time constants against volume. (f) Calculated synaptic weight change mean and SEM (n = 50) at the last time point for all idealized and realistic spines shows an increasing trend against volume. r² = 0.4635 for the linear fit. (g) All calcium peaks as mean and SEM (n = 50) across surface area show a clear increasing trend. r² = 0.5327 for the linear fit. (h)r² = 0.1427 for the fit of decay time constants against surface area. (i) Calculated synaptic weight change mean and SEM (n = 50) at the last time point for all idealized and realistic spines shows an increasing trend against surface area. r² = 0.3887 for the linear fit. (j) All calcium peaks as mean and SEM (n = 50) across volume- to- surface- area ratio show an overall increasing trend. r² = 0.351 for the linear fit. (k)r² = 0.1114 for the fit of decay time constants against volume-to-surface-area ratio. (l) Calculated synaptic weight change mean and SEM (n = 50) at the last time point for all idealized and realistic spines shows an increasing trend against volume-to-surface- area ratio. r² = 0.2815 for the linear fit. (m) All calcium peaks as mean and SEM (n = 50) across PSD surface area to PM surface area ratio show an overall increasing trend. r² = 0.1441 for the linear fit. (n)r² = 0.0428 for the fit of decay time constants against PSD-to-surface-area ratio. (o) Calculated synaptic weight change mean and SEM (n = 50) at the last time point for all idealized and realistic spines shows an increasing trend against PSD-to-surface-area ratio. r² = 0.1186 for the linear fit. Inset above e: legend for all plots.