How the Mood Stability Index is calculated

The idea is simple: we measure how much your mood moved around during the week, then convert that “movement” into a 0–100 stability score. We also show your weekly average mood so you can interpret stability correctly (a stable week at 3/10 feels very different from a stable week at 8/10).

You enter seven mood ratings from 1 to 10. These are treated as a weekly time series: Day 1, Day 2, … Day 7.

We compute the average mood:
Average Mood = (D1 + D2 + D3 + D4 + D5 + D6 + D7) / 7

We compute the standard deviation (SD), a common variability measure:
SD = sqrt( Σ (Di − Average Mood)² / 7 )

In plain language: SD is small when your days cluster near the average and larger when your days are spread out (big ups and downs).

On a 1–10 mood scale, the maximum possible SD (extreme swing case like alternating 1 and 10) is roughly 4.5. We scale your SD against that maximum to create stability:

Base Stability = 100 × (1 − (SD / 4.5))

Then we apply a small context adjustment using optional inputs:

• Stress: Higher stress slightly reduces stability (because it often increases swings).
• Sleep: Lower sleep slightly reduces stability; adequate sleep nudges it up.
• Social connection: Higher connection slightly boosts stability.

These adjustments are intentionally small so the main driver remains your week’s mood pattern. Final results are clipped to 0–100.

• Is: A weekly variability snapshot to support reflection and tracking.
• Is not: A diagnosis, a mental health screening, or medical advice.

How to read your result

Your score is easiest to understand when you look at two numbers together: Mood Stability (0–100) and Average Mood (1–10). You can have a stable week that’s low mood (steady but heavy) or a volatile week that’s high on average (amazing peaks, but with crashes). Both patterns matter.

• 85–100 (Very steady): Your mood stayed relatively even. Great for productivity and calm routines.
• 70–84 (Mostly steady): Some bumps, but no major rollercoaster. A normal healthy pattern for many people.
• 50–69 (Mixed): Noticeable swings. You might be reacting strongly to events, sleep, stress, or social context.
• 0–49 (Volatile): Big ups and downs. Could be lifestyle factors, burnout, irregular schedule, or intense week events.

• High stability + high average: “Steady good week.” Keep your routines.
• High stability + low average: “Consistently low.” Consider support + small mood-lifting habits.
• Low stability + high average: “High highs + crash.” Focus on recovery and consistency.
• Low stability + low average: “Rough and swingy.” Reduce stressors; seek support if needed.

The most useful move is not chasing a perfect number—it's noticing patterns. If your stability is low, ask: Which day dropped? What happened before it? Sleep? Conflict? Work pressure?

Realistic examples (with calculations)

Here are three common weekly patterns so you can sanity-check your result. (Numbers are approximate; your calculator result will be exact.)

Inputs: 6, 6.5, 6, 7, 6.5, 6, 6.5

• Average mood ≈ 6.36
• SD ≈ 0.33
• Base Stability = 100 × (1 − 0.33/4.5) ≈ 93

Interpretation: You had a consistent week. Even if nothing “amazing” happened, consistency is often what your nervous system loves.

Inputs: 8, 7, 4, 6, 9, 5, 7

• Average mood ≈ 6.57
• SD ≈ 1.67
• Base Stability ≈ 63

Interpretation: You still averaged okay, but your week had real spikes and dips. If this repeats, it may help to add a recovery routine (sleep consistency, walks, boundaries).

Inputs: 2, 9, 3, 10, 2, 9, 1

• Average mood ≈ 5.14
• SD ≈ 3.65
• Base Stability ≈ 19

Interpretation: Big swings. This doesn’t mean anything “wrong” with you—it often means the week was intense. Look for triggers and buffers. Consider talking to someone if the pattern is frequent and distressing.

Use this like a weekly “mood dashboard”

The simplest way to use this tool is to treat it as a repeatable weekly routine. Once per week:

• Enter your 7 daily mood ratings (or estimate them if you didn’t track daily).
• Save the result (the calculator stores it locally).
• Write one sentence: “What was the biggest driver of my week?”
• Pick one tiny experiment for next week (sleep, sunlight, journaling, social time, exercise).

Over 4–8 weeks, you’ll start to see patterns. The goal isn’t perfection. The goal is knowing what tends to stabilize you (and what destabilizes you) so you can design more predictable weeks.

• One stabilizer habit: same wake time 5 days this week.
• One stress dial: remove one optional commitment.
• One mood buffer: 10–15 minutes outside daily.
• One connection: schedule one real conversation.

If your average mood is low for multiple weeks, consider reaching out to a professional. Tools are helpful, but support is powerful.

Frequently Asked Questions

• What’s a “good” Mood Stability Index?

  It depends on context. Many people land between 60–85 in normal weeks. If you’re consistently under 50, it may help to look for lifestyle triggers (sleep, workload, conflict) and add stabilizers. A high score is usually helpful, but if the average mood is low, stable low mood still matters.

• Why do you use standard deviation?

  Standard deviation is a simple way to summarize “how spread out” your week was. It’s widely used for variability (including in many tracking contexts). Here it gives a single, understandable number: bigger SD = bigger swings = lower stability.

• Do I need exactly 7 days?

  This calculator is tuned for 7 days because weeks are intuitive. If you only remember 5 days, estimate the missing days using your best guess. For more accuracy, track daily for two weeks and compare.

• Can I improve my score quickly?

  Often yes—because many swings are “lifestyle-driven.” The fastest stabilizers are usually: consistent sleep timing, hydration + regular meals, daily movement, and reduced evening doomscrolling. But if swings are driven by bigger life stressors, support and time matter more.

• Is this a mental health test?

  No. It’s a tracking-style reflection tool. If you’re worried about anxiety, depression, bipolar disorder, or anything serious, talk to a licensed professional. If you’re in immediate danger or crisis, contact local emergency services.

• Why are stress/sleep/social optional?

  Because not everyone wants extra inputs. They lightly adjust the result for context, but the core score is driven by your 7 mood numbers. If you leave optional fields blank, the calculator still works.

• Does a stable week mean a “better” week?

  Not always. Some life seasons are naturally intense (new job, exams, breakup, new baby). Stability is one useful dimension, not the only one. Your best week might have low stability but high meaning.

Make it viral (in a good way)

Want this to be fun with friends? Try one of these:

• “7 Numbers Challenge”: Everyone drops their last 7 mood scores, then compares stability.
• “Steady Week Streak”: Post your score weekly for 4 weeks and see if routine helps.
• “Before vs After”: Compare a high-stress week to a calm week (vacation, holiday, etc.).
• Couples version: Compare each person’s stability for the same week and talk about triggers/buffers.

If sharing makes you feel judged, keep it private—your data is for you first.