Multi-Cloud Egress Cost Comparison Calculator

Why compare multi-cloud egress rates

Cloud teams often watch compute and storage spend closely, then discover that outbound data transfer is what makes a supposedly balanced design expensive. Multi-cloud egress is hard to judge by intuition because the per-GB number looks small until it is multiplied by real traffic. This calculator keeps the comparison simple: use one volume, enter one rate for each provider, and see the flat-rate estimate side by side.

The goal is not to replace a pricing workbook. It is to give you a fast answer when you need to know whether AWS, Azure, GCP, or another provider looks cheapest for the same outbound workload. Because every option is calculated from the same transfer volume, the table shows both the ranking and the dollar gap that grows as volume increases.

That makes the page useful for migration planning, vendor review, capacity budgeting, and any conversation where egress might be the hidden difference between two architectures. A tiny per-GB spread can be easy to ignore at 100 GB and impossible to ignore at 100,000 GB.

What the AWS, Azure, GCP, and custom inputs mean

Before you compare egress costs, it helps to be clear about what each field represents in the cloud billing scenario you are modeling.

Data Volume (GB) is the total amount of data leaving the provider during the period you care about. Most teams use a monthly number because cloud bills are usually monthly, but the model works for any period as long as you keep the same period for every rate. If your reporting source shows terabytes, convert before entering the value. For example, 1.2 TB is roughly 1,200 GB in a simple decimal planning model. The calculator does not convert units for you, so entering 1.2 when you mean 1,200 would understate the result by a factor of one thousand.

AWS Cost per GB, Azure Cost per GB, and GCP Cost per GB are the flat egress rates you want to compare. In a simple planning scenario, these can be the headline internet egress prices that match your traffic class. In a more realistic review, they might be blended values from a recent invoice, negotiated enterprise rates, or the effective price after a free allowance is used up. The key is consistency: each rate should describe the same kind of outbound traffic for the same decision.

Custom Provider Cost per GB is there for any fourth option you want to test. Use it for a smaller cloud, a private cloud reseller, a CDN-backed outbound path, or a negotiated offer from another vendor. The calculator treats the custom field the same way as the others when it is filled in. If you leave it blank, the comparison simply uses AWS, Azure, and GCP.

It is also worth pausing on what your volume number actually represents. Are you comparing public internet traffic, only one service’s downloads, cross-cloud replication, or a specific export job? The calculator can only answer the scenario you define. A focused question such as How much would 12 TB of monthly customer downloads cost on each provider? produces a far better decision than a vague question such as What are our egress costs?

How the multi-cloud egress formula works

For this calculator, the math is one multiplication per provider: transfer volume times that provider’s per-GB egress rate.

In that formula, C is the estimated egress cost, V is your data volume in gigabytes, and r is the provider’s egress rate in dollars per gigabyte. If you compare several providers, the calculator repeats the same multiplication for each one and then identifies the smallest result as the current low-cost option.

If a cloud bill includes tier breaks, different destinations, or a negotiated blended rate, split those pieces apart before you compare them here. The calculator is designed for one flat rate per provider, which makes it useful for early screening even when the final invoice is more complicated.

Worked example: 1,200 GB across four providers

To see the comparison in numbers, imagine a team expects to send 1,200 GB of outbound traffic next month. They enter these rates: AWS $0.090 per GB, Azure $0.087 per GB, GCP $0.085 per GB, and a custom provider at $0.078 per GB. The resulting estimates are straightforward:

• AWS: 1,200 × 0.090 = $108.00
• Azure: 1,200 × 0.087 = $104.40
• GCP: 1,200 × 0.085 = $102.00
• Custom: 1,200 × 0.078 = $93.60

In that scenario, the custom provider is cheapest, GCP is the lowest among the three large public clouds, and AWS is the most expensive of the listed options. The useful planning insight is not merely the ranking. It is the magnitude of the difference. AWS versus GCP differs by only $6.00 at 1,200 GB, which might be too small to matter if another factor dominates the decision. Yet if the same workload grows to 12,000 GB, the AWS-versus-GCP gap becomes $60.00, and at 120,000 GB it becomes $600.00. Small rate differences scale linearly with volume.

That is why scenario testing matters. If you are unsure whether a new product launch, backup export, analytics feed, or multi-cloud replication job will send 800 GB or 8,000 GB, run both cases. The calculator gives you a quick budget range and shows whether egress pricing is merely a minor detail or something worth actively optimizing.

A quick multi-cloud egress sensitivity view

The table below shows how the AWS-versus-GCP gap grows as monthly transfer volume increases. It uses fixed example rates so you can see the scale effect without changing the calculator inputs.

Notice how the ordering never changes in this flat example, but the financial impact does. This is one reason finance, platform, and product teams sometimes talk past each other. A platform engineer may correctly say the rates are close together, while a finance lead may correctly say the annual budget impact is material. The calculator helps both groups use the same numbers.

How to interpret the multi-cloud result table

After you press Compare, the results area lists the estimated cost for each provider and highlights the lowest-cost row in bold. Start with the summary sentence above the table. It tells you which option is currently cheapest for the volume you entered and how much lower it is than the next best option. That gap is often more important than the absolute total because it shows how much savings is actually available if egress price is the only factor.

From there, ask a few grounded questions. Does the unit match the way the rate is billed? Are all rates for comparable traffic types? Did you use the same period for the transfer volume and the rates? If the numbers look surprisingly high, the most common causes are a volume unit mistake, entering a per-terabyte figure as if it were per gigabyte, or comparing internet egress for one provider with regional peering traffic for another. If the numbers look too low, the usual culprit is a missing zero in the transfer volume or a rate that reflects only a discounted first tier.

The result table is best used as a decision support tool, not as a final invoice predictor. It tells you what flat-rate pricing would imply for the scenario in front of you. That is enough detail for many early design questions: whether to keep data near the workload, whether to add caching, whether to compress outbound payloads, or whether a multi-cloud pattern is likely to be affordable before you invest more time.

Assumptions and limitations of flat-rate egress comparisons

This comparator uses a flat-rate model for multi-cloud egress, so it deliberately leaves out the parts of a cloud invoice that depend on tiers, regions, or contract terms. Real cloud bills can be more complicated. Many providers apply volume tiers, different rates by region, destination-specific pricing, special pricing for CDN or peering paths, or discounted terms under enterprise agreements. Taxes, support costs, and minimum commitments are also outside the scope of this page. None of those details mean the calculator is unhelpful; they simply explain what kind of question it answers well. It is excellent for fast comparisons, rough budgeting, and early architecture tradeoff conversations.

It also assumes that all traffic being compared is outbound traffic that would actually incur the listed egress charge. Inbound transfers are usually free or priced differently, so they are not included here. If you are modeling replication between clouds, inter-region transfer, or movement into a CDN edge, make sure the rate you enter truly matches that route. When in doubt, use a recent invoice or the provider’s latest pricing table for the exact transfer pattern you care about.

If you need more realism, a good next step is to break the problem into chunks. For example, separate traffic by region, by customer geography, by public internet versus private link, or by base-load versus burst traffic. Then calculate each chunk individually and add the subtotals. That workflow mirrors the single-rate formula above and usually gets you much closer to a bill-like estimate without turning a quick calculator into a full spreadsheet exercise.

Finally, remember what drives the bill: volume and rate. Performance, latency, operational fit, data gravity, service compatibility, and contractual commitments can still outweigh a cheaper egress line item. A price comparison is useful because it makes the tradeoff explicit, not because it should always decide the architecture on its own.