Calculate sustainable TLS handshake rate from core count, key algorithm and resumption rate, plus the round trips setup costs.
Handshake capacity is set by asymmetric signing throughput, which depends entirely on the key algorithm and size. Resumption replaces that operation with a symmetric key derivation costing roughly a twentieth as much, so a high resumption rate multiplies effective capacity. Handshake rate — not throughput — is what falls over during a thundering-herd reconnect after a deployment, and TLS 1.3 halves the user-visible setup latency on top of that.
TLS Handshake Rate
handshake rate = cores × operations per core ÷ ((1 − resumption rate) + 0.05 × resumption rate), since a resumed handshake costs about 5% of a full one.
handshake rate = cores × operations per core ÷ ((1 − resumption rate) + 0.05 × resumption rate), since a resumed handshake costs about 5% of a full one. Handshake capacity is set by asymmetric signing throughput, which depends entirely on the key algorithm and size. Resumption replaces that operation with a symmetric key derivation costing roughly a twentieth as much, so a high resumption rate multiplies effective capacity.
Handshake rate — not throughput — is what falls over during a thundering-herd reconnect after a deployment, and TLS 1.3 halves the user-visible setup latency on top of that.
This calculator takes 5 inputs: CPU cores dedicated to TLS, Certificate key type, Handshakes resumed, TLS version, Network round-trip time. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.