Traffic Routing Calculator
Split traffic across weighted origin pools and see the blended latency, plus what happens when a pool drops out.
Inputs
Blended Latency
60.00ms
Pool A Share
60.0%
Pool B Share
30.0%
Pool C Share
10.0%
Requests to Pool A
300.00million
Requests to Pool B
150.00million
Blended Latency Without Pool A
82.50ms
Latency Penalty if Pool A Is Lost
22.50ms
Step by step
Values used
Requests per month = 500 million; Pool A weight = 60 weight; Pool B weight = 30 weight; Pool C weight = 10 weight; Pool A latency = 45 ms; Pool B latency = 70 ms; Pool C latency = 120 ms; Pool health = All three pools healthy
Traffic Routing
pool share = pool weight ÷ sum of healthy weights; blended latency = Σ(weight × pool latency) ÷ sum of healthy weights, with unhealthy weights removed before normalising.
Blended Latency
= 60.00 ms
Pool A Share
= 60.0
Pool B Share
= 30.0
Pool C Share
= 10.0
Requests to Pool A
= 300.00 million
Requests to Pool B
= 150.00 million
How it works
Weighted routing normalises against the sum of healthy weights, so ejecting a pool silently redistributes its share to the survivors in proportion to their own weights rather than evenly. Blended latency is the weighted mean, which is why sending even 10% of traffic to a distant pool moves the average far less than it moves that 10% of users. The blended number is what your dashboard shows and the per-pool number is what those users feel, so weighted routing can look healthy while a tenth of your traffic is served twice as slowly — and the failure case shows what happens when the nearest pool is the one that drops.
Formula
Traffic Routing
pool share = pool weight ÷ sum of healthy weights; blended latency = Σ(weight × pool latency) ÷ sum of healthy weights, with unhealthy weights removed before normalising.
- healthy weights
- Weights of pools currently passing their health check
- blended latency
- Weight-averaged latency across the pools actually in rotation
- latency penalty
- Increase in blended latency once the best pool is removed
Frequently Asked Questions
How is Traffic Routing calculated?
pool share = pool weight ÷ sum of healthy weights; blended latency = Σ(weight × pool latency) ÷ sum of healthy weights, with unhealthy weights removed before normalising. Weighted routing normalises against the sum of healthy weights, so ejecting a pool silently redistributes its share to the survivors in proportion to their own weights rather than evenly. Blended latency is the weighted mean, which is why sending even 10% of traffic to a distant pool moves the average far less than it moves that 10% of users.
Why does Traffic Routing matter?
The blended number is what your dashboard shows and the per-pool number is what those users feel, so weighted routing can look healthy while a tenth of your traffic is served twice as slowly — and the failure case shows what happens when the nearest pool is the one that drops.
What values do I need to enter?
This calculator takes 8 inputs: Requests per month, Pool A weight, Pool B weight, Pool C weight, Pool A latency, Pool B latency, Pool C latency, Pool health. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.
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