Carrier Performance and SLAs: What Brands Need to Know and Measure

Is your carrier ruining your customer relationships? (Are you sure?) The final stretch of an online delivery is where you make or break the customer relationship. It’s often also the most expensive and operationally complex part of the fulfillment process. For most eCommerce and DTC brands, last-mile delivery success depends entirely on your carrier’s performance, which is why their performance and your SLA are so important.

But what should your carrier SLA cover, and what metrics should you be measuring and holding your carrier accountable to? In this article, we outline the carrier performance metrics that matter and break down the key components of an SLA that will protect your brand while delivering last-mile success.

Why Last-Mile Carrier Performance Matters More Than Ever

Consumer expectations for shipping are already high, and they’re getting even higher. Digital Commerce 360’s research shows that 93% of customers want to stay informed throughout the delivery process, 47% won’t return to a brand with poor delivery visibility, and 98% say delivery is a key part of their brand loyalty.

The post-purchase experience is no longer simply logistics; it’s a competitive differentiator that shapes brand perception and determines success.

What’s more, while a late delivery, missing package, or damaged item might be the fault of your carrier, ultimately it’s your brand that gets the blame and suffers the consequences. That’s why establishing a strong carrier SLA that maximizes performance and minimizes errors is crucial.

What Makes an Effective Carrier Agreement

A carrier service level agreement is more than a contract; it’s a performance roadmap that defines what “good” is, how it’s measured, and what happens when it’s not met.

For last-mile delivery, your SLAs should focus on outcomes that directly impact customer satisfaction and operational efficiency. Do not fall for a generic agreement—you need metrics tailored to the specific challenges of your business, be that residential deliveries, tight delivery windows, or high customer expectations.

Here’s an example of what an effective carrier SLA should include:

1. Clear performance metrics

Define precisely what you’re measuring and set specific targets, for example, an on-time delivery rate of 97.5% or higher, or a claims rate below 1%. Defining clear performance metrics sets expectations and allows you to intervene when things aren’t going to plan.

2. Service level agreements (SLAs)

Turn your business goals into performance targets that your carriers must hit. For example, if your brand promises two-day delivery, your carrier SLA should guarantee two-day delivery at least 95% of the time. Build in assurances, non-negotiables, and what happens when carriers fail to deliver (pun intended) on their promises–more on that below.

3. Accountability and remedies

Outline what happens when a carrier fails to meet targets, for example, service credits, refunds, or the ability to renegotiate terms. Without penalties, you risk your SLA becoming a suggestion rather than a commitment.

4. Reporting and transparency

Agree on how often you’ll run performance reports and what real-time data you’ll have access to. Ideally, you should have real-time visibility of delivery times, exception rates, and customer complaints, allowing you to spot trends early and address issues before they compound.

5. Flexibility for growth

Your shipping needs will change as your business scales, which is why provisions that allow you to increase volume commitments, add new service levels, or expand into new regions without renegotiating the entire agreement are crucial.

Still in negotiations with your carriers? Here are the carrier contract negotiation strategies you need to know.

Carrier Key Performance Metrics

You measure and report on eCommerce KPIs from across your business; carrier KPIs should be no different. There are plenty of performance metrics you can measure, but ideally, you want to focus on the ones that directly impact customer experience, cost efficiency, and operational reliability.

Here are the critical KPIs every brand should track:

On-time delivery rate

On-time delivery rate measures how often packages arrive by the promised delivery date. It’s the metric most visible to customers and the clearest indicator of carrier reliability.

According to internal iDrive analysis of 100,000 shipments across carriers like UPS, FedEx, USPS, and Amazon Shipping, you should expect an on-time delivery rate of at least 97.5%. Anything below 94% signals a problem that needs immediate attention.

Tip: Tracking on-time delivery by service level and zone helps inform your multi-carrier shipping strategy by identifying the right carriers for the right deliveries. For example, a carrier might excel at standard deliveries in urban areas but struggle with express shipping to rural zip codes.

First-attempt delivery

First-attempt delivery measures how often your carriers successfully deliver a parcel the first time. Carriers with high first-attempt delivery rates reduce your overall delivery costs, lower your carbon footprint, and improve customer satisfaction. A low first-attempt score indicates either a problem with your carrier’s performance or issues within your fulfillment operation (e.g., the lack of address validation tools).

Delivery damage and claims rates

Damaged packages are frustrating for all involved: a customer doesn’t receive their order as promised and has to contact you, your logistics team has to arrange a return, and you have to process and swallow the refund. That’s a lot of hassle stemming from your carrier’s handling standards.

To calculate your damaged delivery rate, divide the number of claims by the total number of packages shipped, then multiply by 100. Industry standards suggest a rate of 1% or less.

Note: Carrier handling isn’t always the cause behind high damage rates. Check your packaging is up to standard, especially for large, heavy, and fragile items.

Scan compliance and tracking accuracy

Customers want real-time visibility into their order’s journey, which is why a carrier’s failure to scan packages at key checkpoints can lead to a “where is my order?” inquiry, causing customer frustration and clogging up your support team’s time. Monitoring a carrier’s ability to provide that real-time visibility allows you to intervene when standards aren’t being met.

Transit time accuracy

This metric measures the average difference between the estimated and actual delivery times. The goal is for orders to arrive within the delivery window, not before, and certainly not after. Don’t forget that many customers will plan their diaries around a delivery, so while an early delivery might sound great, in reality, it can just be as frustrating as a late one.

Don’t forget: Transit time accuracy is crucial for time-sensitive items, such as perishables, pharmaceuticals, and gifts.

Cost per delivery

Last-mile delivery costs are expensive, but they shouldn’t be unpredictable. Keep track of your total landed shipping cost, including base rates, surcharges, fuel fees, and any other fees. You can then compare this average across carriers and service levels to identify any areas of concern. Sometimes a carrier with a slightly higher base rate delivers lower total costs because they impose fewer surcharges or have better zone coverage.

Peak season capacity and performance

Peak seasons test relationships, and your carriers aren’t excluded from that. Demand surges, capacity tightens, and performance often declines. Pay close attention to your carrier performance during busy periods to ensure it’s meeting the goals agreed in your SLA. If a particular carrier can’t handle your peak volumes, they might not be the right long-term partner for your business.

Further reading: Peak Season Fulfillment: How to Prepare Logistics to Scale

How to Create a Carrier Performance Scorecard

A carrier performance scorecard combines all your metrics into a single view, making it easier to track performance, compare carriers, and make decisions. Here’s how to create one:

Weigh your metrics

Your metrics aren’t all equally important, so take the time to assign weights based on what matters most to your business. For example, suppose customer satisfaction is your top priority. In that case, on-time delivery might carry 40% weight, whereas if low prices are what your customers care about, cost will matter more than speed.

Set performance threshold

Establish clear benchmarks for acceptable, good, and excellent performance. For example:

• Acceptable: 95% on-time delivery
• Good: 97% on-time delivery
• Excellent: 99% on-time delivery

Color-coded scorecards (red, yellow, green) make it easy to identify performance at a glance.

Review regularly

Performance scorecards aren’t a one-time event. Review them monthly or quarterly to spot trends, identify issues, and adjust your carrier mix as needed. The goal is to address underperformance concerns before they become significant problems for your customers.

Use scorecards in negotiations

When it’s time to renegotiate a carrier contract, scorecards become your strongest tool. Carriers that consistently underperform lose leverage, while top performers earn loyalty and potentially more volume. Scorecards also help you make objective decisions about adding or removing carriers from your network, providing the data to support strategic decisions.

Conclusion

Carrier performance shouldn’t be a difficult conversation; it should be your competitive advantage. SLAs, defined performance indicators, and carrier performance scorecards help you define accountability, set clear expectations, and demand better performance. All of this enables a last-mile delivery experience that customers return for.

At iDrive, we help eCommerce brands and 3PLs turn carrier management into a strategic advantage. Through our TMS platform and analytics dashboard, you get visibility into carrier performance, access to a diversified carrier network, transparent billing, and contract-engineering support to optimize costs, service and margins.

Ready to optimize your carrier network? Discover how iDrive delivers better last-mile performance.