The EIGRP K values are used to calculate the EIGRP metric, by default the metric is based on constrained bandwidth, and cumulative delay but can be configured to use Link load, reliability & MTU. Cisco Recommends that Link Load & Reliability are not used in the metric as these values change rapidly due to network conditions and results in frequent convergence.

The delay is a calculated as the cumulative total delay of the path through the network, this is measured in tens of microseconds so a 10millisecond (ms) delay = 1000 tens of microseconds.

The bandwidth is calculated in the minimum interface bandwidth available and measured in kB.

If the default K-Values are used the Bandwidth and Delay are scaled with the following formula
EIGRP metric = 256(10000000/bandwidth)+256(delay)

The full official formula which includes all the K values is as follows;
EIGRP metric = [K1 * bandwidth + (K2 * bandwidth) / (256 - load) + K3 * delay] * [K5 / (reliability + K4)]

The K values can be changed with the following command
metric weights tos k1 k2 k3 k4 k5

Where; k1 = bandwidth, k2 = load, k3 = delay, k4 = reliability & k5 = MTU.