VPN Speed & Privacy Tradeoff Calculator
Estimate your VPN's privacy score and expected speed reduction based on encryption strength, tunneling protocol, server distance, and base connection speed.
Formulas Used
Effective VPN Speed (Mbps):
effectiveSpeed = baseSpeed
× (1 − encryptionOverhead)
× (1 − protocolOverhead)
× (1 − latencyPenalty)
× (1 − multihopPenalty)
× (1 − obfuscationPenalty)
Speed Reduction (%):
speedReduction% = (1 − effectiveSpeed / baseSpeed) × 100
Added RTT (ms):
addedRTT = serverDistance_km / 100 [fiber propagation ≈ 2/3 × c → 200,000 km/s → 2×distance/200,000×1000]
Latency Speed Penalty:
latencyPenalty = min(addedRTT_ms / 1000, 0.40)
Privacy Score (0–100):
rawPrivacy = encryptionScore + protocolScore + multihopBonus
+ obfuscationBonus + dnsBonus + killSwitchBonus
privacyScore = (rawPrivacy / 85) × 100 [85 = maximum raw points]
Tradeoff Efficiency Index:
tradeoffIndex = privacyScore / (speedReduction% + 1)
Assumptions & References
- AES hardware acceleration (AES-NI) is assumed for AES-128/256; overhead figures reflect modern CPUs.
- Fiber propagation speed ≈ 200,000 km/s (≈ 2/3 of c in vacuum), per standard optical fiber models.
- Latency penalty is capped at 40% to reflect real-world TCP congestion window behaviour at high RTT.
- Protocol overhead values are derived from published VPN speed benchmarks (NordVPN, ExpressVPN, Mullvad, WireGuard whitepapers).
- Privacy scores are weighted heuristics based on NIST encryption strength guidelines, VPN protocol security audits, and EFF recommendations.
- Multi-hop (double VPN) roughly doubles latency overhead and adds ~10% extra encryption cost.
- Obfuscation overhead (~15%) reflects typical Shadowsocks / obfs4 proxy measurements.
- DNS leak protection and kill switch contribute to privacy posture but have negligible throughput impact.
- Server load, ISP throttling, and hardware limitations are not modelled.
- References: WireGuard paper (Donenfeld, 2017); RFC 3193 (L2TP); RFC 7296 (IKEv2); Cloudflare QUIC/TLS benchmarks.