Cosmological constraints in flat ΛCDM from the mock sample of 20 lensed SN Ia systems with good time-delay measurements. Grey contours/histograms show the marginalised constraints from having only D_Δt measurements, orange are those from only D_d measurements, and blue are the results based on both D_Δt and D_d measurements. The dashed contours indicate the 68%, 95%, and 99.7% credible regions, whereas the vertical dashed lines in the histograms indicate the 68% credible intervals. The input values are denoted in black and are recovered within the marginalised 68% credible intervals in 1D (or within the 95% credible regions in the 2D H₀ − Ω_m plane). In flat ΛCDM, even a modest sample of 20 lensed SNe Ia could constrain H₀ and Ω_m with precisions of 1.3% and 19%, respectively.