Edge cache in this calculator is saving from hit rate minus fixed edge. With 2000000 requests, 70 hit %, 0.0004 origin USD, 0.00008 edge USD, 250 fixed USD the result is $150.00 | $650.00.
before = requests × origin. after = hit × edge + miss × origin + fixed. saving = before − after. The formula uses hit rate and origin.
$150.00 | $650.00 is not a CloudFront price list. Another set of numbers gives -$36.00 | $276.00, and a further set gives $800.00 | $1,200.00. Empty scenario fields do not change the result.
Egress cost answers a different question. Cold start does too. Here 2000000 requests, 70 hit %, 0.0004 origin USD, 0.00008 edge USD, 250 fixed USD leave $150.00 | $650.00.
Type 2000000 requests, 70 hit %, 0.0004 origin USD, 0.00008 edge USD, 250 fixed USD and click Calculate. Two more ready sets sit under the form: -$36.00 | $276.00 and $800.00 | $1,200.00.
Other numbers on the same labels move the result. The first example gives $150.00 | $650.00.