Spot interest rate
= Spot interest rate
The time-$t$ one-period spot interest rate is the rate available for investment from $t$ to $t+1$. For a unit-face-value <zero-coupon bond>,
$$
1+r_t=\frac1{P_t^{t+1}}.
$$
= Spot interest rate
The time-$t$ one-period spot interest rate is the rate available for investment from $t$ to $t+1$. For a unit-face-value <zero-coupon bond>,
$$
1+r_t=\frac1{P_t^{t+1}}.
$$