What Is SLI (Satisfaction Level Indicator)?

SLI (Satisfaction Level Indicator) is a customer experience KPI that compresses all collected feedback into one score between −100 and 100. It is calculated as SLI = (Current case × 100) / Best case — your actual feedback scores measured against the best result those same customers could have given.

The SLI formula, step by step

SLI starts from a five-level rating scale. Each answer a customer gives is mapped to a score:

• Excellent = +10
• Good = +5
• Neutral = 0
• Bad = −5
• Unacceptable = −10

Two totals are then computed:

• Best case — the score if every response had been Excellent: total response count × 10.
• Current case — the score your responses actually produced: each count multiplied by its score, summed.

The indicator is the ratio of the two, scaled to 100: SLI = (Current case × 100) / Best case. Because negative ratings subtract points, the result ranges from −100 (every response Unacceptable) to 100 (every response Excellent).

Note what the design choices do. The five-point scale keeps the question answerable in one tap at a kiosk or in an SMS. The symmetric scoring (+10 to −10) means a bad experience costs exactly as much as a great one earns — the indicator cannot be propped up by volume alone. And dividing by the best case normalizes for response count, so a branch with 80 responses and a branch with 8,000 sit on the same scale.

A worked example

Suppose a business collects 250 responses in a month: 181 Excellent, 26 Good, 4 Neutral, 27 Bad and 12 Unacceptable.

Best case: 250 × 10 = 2500

Current case: (181 × 10) + (26 × 5) + (4 × 0) + (27 × (−5)) + (12 × (−10)) = 1810 + 130 + 0 − 135 − 120 = 1685

SLI: (1685 × 100) / 2500 = 67.4

Run the same calculation next month and the two numbers are directly comparable, whatever the response volume was — that is what the best-case denominator buys you. Track it weekly per location and the indicator becomes an early-warning system rather than a report.

An SLI of 67.4 lands in the excellent band — but the same calculation shows exactly where the ceiling is: the 39 negative responses cost 255 points plus the 390 they could have added. The formula makes the cost of every bad experience arithmetically visible, which is precisely what a closed-loop feedback process is there to recover.

SLI score bands: reading the number

These bands match the scale used on the Qmeter SLI page, where the indicator is defined in full.

SLI vs NPS vs CSAT

SLI does not replace the classic metrics — it sits above them as a composite. The differences:

• NPS measures loyalty from one question (“would you recommend us?”) and ignores every other rating you collect. Strong for relationship tracking, blind to day-to-day service quality.
• CSAT measures satisfaction with one interaction and is usually reported as a percentage of positive answers — which means a “Bad” and a “Neutral” can count the same: not positive.
• SLI uses every rating from every touchpoint, weights negative experiences as negative numbers, and benchmarks the total against perfection. One survey response can move NPS or CSAT for that survey; SLI moves only as the whole operation moves.

In practice the three coexist: transactional CSAT at touchpoints, periodic NPS for loyalty, SLI as the headline trend. For the full comparison of the underlying metrics, see NPS vs CSAT vs CES.

How to improve an SLI score

Because SLI is arithmetic over your ratings, there are only two ways to move it — and the formula tells you which one pays more right now:

• Eliminate negatives first. Converting one Unacceptable (−10) into a Good (+5) swings 15 points of current case; converting a Good into an Excellent adds 5. Rescuing the angriest customers is three times more productive than polishing the satisfied ones, which is why routing and resolving negative feedback fast comes before anything else.
• Then convert Good into Excellent. Once negatives are rare, the remaining gap to 100 is the mass of +5 ratings. These customers tell you exactly what is missing — their open comments are the improvement backlog.

Two disciplines keep the number honest. Collect at every transaction, not just from customers likely to be pleased — selective collection inflates SLI and blinds you. And never chase the score by pressuring customers for top ratings; a flattered indicator defeats the purpose of having one.

Why one number works for operators

Multi-location businesses drown in partial metrics: NPS from the quarterly campaign, CSAT from support, star ratings from the app, smiley presses from the lobby. Each is real; none is comparable. SLI exists because an operations director needs one honest answer per branch, per week: better or worse?

• Comparable across branches — every location is scored against the same best case, so branch 3 at 71 and branch 9 at 12 is a finding, not a formatting problem.
• Sensitive to harm — negative scores subtract, so a location generating angry customers cannot hide behind a large pile of merely-fine ratings.
• Trend-friendly — one line per branch on one chart is something a Monday meeting can actually act on. It is the natural headline for the whole customer experience management cycle.

A single number is a summary, not a diagnosis — and that is the point. When the weekly SLI line dips, the questions that follow are the productive ones: which branch, which channel, which theme in the comments. The indicator’s job is to make sure those questions get asked the week the problem starts, not the quarter after it has compounded.

How Qmeter helps

SLI is native to Qmeter: the platform computes it continuously from every response collected across web, email, SMS, QR and in-location kiosks, and shows it per branch, per period and company-wide. Real-time alerts fire when a location’s SLI drops, and AI analysis of open comments explains the movement behind the number. You can see your first SLI within days of starting — AI builds the survey from your company profile, plans are public from €500/year on the Qmeter pricing page, and the 14-day free trial needs no credit card.