What is usage-based billing? How it works and how to set it up

Key takeaways

• Usage-based billing charges customers for what they actually consume; hybrid plans may also include a base fee or usage allowance.

• Revenue can scale with customer activity, which may suit some SaaS and AI businesses better than a subscription-only model.

• Airwallex Usage-based Billing lets you define meters without code, send usage events through an API and view usage and estimated charges in real time.

Usage-based billing charges customers for what they use – such as API calls, gigabytes stored, messages sent, or any other unit of consumption – instead of a fixed ongoing fee. The model is used across cloud services, AI and SaaS, with pure usage-based billing models, fixed models, and hybrid models available to businesses.

If you're a founder or finance lead weighing up the switch, the appeal is straightforward: revenue that tracks the value customers actually get from your product, rather than a number you picked at launch and may have not revisited since. The harder part is building or buying the metering and billing infrastructure to make it work reliably at scale.

This guide will take you through what usage-based billing means, how it compares with subscription billing, and how to set it up with a billing platform such as Airwallex.

What is usage-based billing?

Usage-based billing is a pricing model that charges customers based on how much of a product or service they consume, rather than a fixed recurring fee.

In a pure usage-based model, a customer pays for measured units rather than a fixed monthly fee; hybrid plans can add a base fee or included allowance. The provider tracks consumption, aggregates it into a billable amount, applies the pricing rules and issues an invoice – often automatically and on a set schedule.

It's a model that's spread well beyond tech:

• Cloud storage providers, where you're billed per gigabyte stored

• API and AI platforms, where you're billed per call or per token processed

• Ride-share apps, where the fare reflects distance and time travelled

• Electricity retailers, where usage charges are typically based on kilowatt-hours alongside fixed supply charges and other tariff components

Usage-based billing has expanded beyond infrastructure and telecommunications into AI and SaaS. However, adoption varies: businesses may use fixed, usage-based or hybrid pricing depending on their product and customers.

How does usage-based billing work?

Usage-based billing works by tracking customer activity, then converting that activity into an invoice through four steps.

1. Metering: The system captures usage events as they happen, such as an API call, a gigabyte processed, or a minute of compute time.

2. Rating: Those events are converted into a dollar figure, based on your pricing model, whether that's per-unit, tiered, volume-based or hybrid.

3. Invoicing: Rated usage is compiled into an invoice, typically at the end of a billing cycle, showing what was consumed and what it cost.

4. Payment: The customer pays the invoice through their chosen payment method, and the next billing period begins for subsequent usage.

In practice: an Australian SaaS platform charging 2 cents per API call would meter 50,000 calls in a month, rate that usage at A$1,000 before any applicable GST, generate an invoice for the resulting amount and collect payment according to its configured collection method.

The most important part of this chain is speed. Metering that lags by days makes it hard to give customers accurate real-time usage estimates, and makes it harder for you to catch anomalies before they turn into a disputed invoice. Real-time or near-real-time metering can improve usage visibility, but it is not universal: platforms may also accept pre-aggregated or batch usage data.

Common usage-based pricing models in Australia

Most usage-based pricing falls into one of four models, and many Australian SaaS businesses combine more than one across their product line.

Which model fits depends on how predictable your customers' usage is. Per-unit pricing can suit products with genuinely variable consumption, like API platforms, while tiered and volume-based pricing reward growth and work well where usage climbs steadily over a customer's lifecycle. Hybrid pricing tends to suit businesses that want the revenue floor of a subscription while still capturing upside from their heaviest users.

Usage-based billing vs subscription billing

Usage-based billing ties at least part of the charge to usage; subscription billing typically charges a fixed recurring fee, although plans may include allowances or overages.

Businesses do not have to choose one model outright. A hybrid approach—a base subscription with usage-based overages—can combine more predictable base revenue with usage-linked upside. Airwallex Subscription Management supports simple and hybrid pricing models.

Benefits and challenges of usage-based billing

Usage-based billing brings real upside for growing businesses, but it also introduces new operational demands that flat subscriptions don't. Weighing both sides upfront makes it easier to decide whether – and how – to introduce it.

Benefits

• Lower barrier to entry. Customers can start small and pay only for what they need, which widens your addressable market beyond those willing to commit to a flat fee.

• Revenue that scales with value. Heavy users pay more and light users pay less, so your revenue line reflects the value you're actually delivering.

• Support product-led growth. Free trials and low-commitment entry points can reduce the initial barrier to entry for some customers. 

• More transparent for customers. Can be more transparent when the usage metric is easy to understand and clearly shown on the invoice.

Challenges to plan for

• Revenue forecasting gets harder. Usage can fluctuate month to month, so forecasting needs more inputs than a fixed subscription base provides.

• Bill shock is worth managing. A spike in usage can produce a larger-than-expected invoice, so proactive usage alerts help keep customers ahead of their spend.

• Revenue recognition needs a plan. Usage-based revenue is generally recognised as it's earned rather than upfront, which is worth raising with your finance team early – a planning consideration, not a reason to avoid the model.

How to set up usage-based billing for your business

Setting up usage-based billing starts with choosing what you'll actually charge for, then building the infrastructure to track and bill it accurately.

1. Choose a value metric. Pick the unit that best reflects the value customers get from your product, such as API calls, seats, or data processed.

2. Define your pricing tiers. Decide whether per-unit, tiered, volume-based or hybrid pricing best fits how your customers use your product.

3. Pick a metering and billing system. Build metering in-house, or use a billing platform that handles metering, invoicing and recurring billing in one place.

4. Communicate proactively. Send usage alerts before customers hit unexpectedly large charges, so bill shock doesn't erode trust in your pricing.

5. Monitor and adjust. Review usage data regularly and refine your pricing tiers as your customer base and product mature.

These steps do not necessarily need to be built from scratch. Australian SaaS and AI businesses can use a billing provider that combines usage-event ingestion, metering, invoicing and payment collection, reducing the need to maintain all billing infrastructure in-house; implementation effort still depends on the integration.

Why businesses choose Airwallex for usage-based billing

Airwallex Usage-Based Billing gives Australian SaaS, AI and digital businesses a flexible way to charge for actual product consumption, rather than relying only on fixed subscriptions.

• Supports pay-as-you-go and hybrid models – including a base subscription with usage-based overages – using flat, per-unit, tiered and volume-based pricing structures.

• Lets you define usage meters, send high volumes of usage data via API, and monitor consumption and estimated charges in real time through the Airwallex WebApp or API.

• Supports usage aggregation, billing in arrears, invoice generation, payment collection, and retry and reminder workflows for failed payments, reducing the need to build all billing infrastructure in-house.

• Supports Automatic Tax Calculation for invoices and subscriptions, including Australia, when configured with the relevant tax registrations, product tax categories and valid billing addresses; it does not replace tax advice.

• Supports invoice payment through 160+ payment methods and collection in 130+ currencies; funds can settle into Airwallex Global Accounts, subject to supported-method, currency and account availability.

Together, this gives growing businesses more transparent billing, pricing that scales with customer value, and room to experiment with new monetisation models without building billing infrastructure from scratch. It's also built for businesses expanding beyond Australia, so the same setup that bills a local customer in AUD can bill an overseas customer in their own currency, without a separate system for each market.

Frequently asked questions

What value metric should I use for usage-based billing?

Choose a metric that scales directly with the value customers get from your product – API calls for a developer tool, seats for a collaboration app, or data processed for an AI platform. The right metric feels fair to customers, is easy to explain on an invoice, and grows in line with your revenue as customers get more value from your product.

What is consumption-based billing?

Consumption-based billing is another term for usage-based billing. It charges customers for the actual amount of a product or service they use, rather than a flat recurring fee, and the two terms are used interchangeably across the industry – you'll see both in vendor documentation and pricing pages without any real difference in meaning.

Can you combine subscription and usage-based billing?

Yes. A hybrid model – a base subscription fee plus usage-based overages once an included allowance is exceeded – is common among SaaS and AI businesses. It combines predictable base revenue with upside from heavier users, and is one way to introduce usage-based pricing without disrupting existing subscription customers.

What is the difference between usage-based billing and subscription billing?

Usage-based billing charges customers for what they consume, while subscription billing charges a fixed recurring fee regardless of usage. Usage-based billing scales revenue with customer activity and can lower the barrier to entry; subscription billing prioritises predictable, upfront revenue and simpler administration instead.

What is the difference between metered billing and usage-based billing?

Metered billing refers to the technical process of tracking consumption – the "meter" itself, and the data it produces. Usage-based billing is the pricing model built on top of that data, converting metered usage into an invoice. In practice, the two terms are often used interchangeably.