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SourceLoop

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Free Cohort Retention Curve Generator

Plug in monthly retention rates from your cohort data. See the curve, half-life, average lifespan, and LTV multiplier. Compare against SaaS, ecommerce, and consumer subscription benchmarks.

Inputs

Monthly retention percentages

Enter the percentage of the original cohort still active at each milestone month. Month 0 is always 100%. Skip any month you don't have data for; the curve interpolates.

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Results

Retention curve and key metrics

Average lifespan
Half-life (50% retention)

Retention curve

Metric Value Benchmark

How it works

Three steps from raw cohort data to a defensible LTV

Curve, half-life, lifespan. The three numbers every SaaS investor wants to see.

  1. m1 = 70%
    m3 = 48%
    m6 = 42%
    m12 = 38%
    01

    Plug in retention by month

    Pull from your CRM or analytics. Cohort by signup month for cleanest data. Don't blend cohorts.

  2. 02

    See the curve

    Smile shape good. Linear decline bad. Where the curve flattens tells you whether the product reached habit.

  3. SaaS cohort, Q1

    Mid-market healthy

    • Half-life 2.5 mo
    • Lifespan 26 mo
    • LTV multiplier 26x
    03

    Read the LTV multiplier

    Multiply ARPU × gross margin × lifespan to get LTV. That's the number that justifies CAC, fundraising, and growth math.

Concepts explained

Six concepts that make cohort retention math work

The retention curve is the most overloaded chart in SaaS. These six concepts keep the analysis honest.

Best practices

Five rules for honest cohort retention analysis

  1. 01

    Cohort by signup month, not blended

    Blended retention hides cohort-specific effects. Old cohorts pull blended numbers up. New cohorts pull them down. Always cohort.

  2. 02

    Look for the flattening point

    Where the curve flattens is where you reached product-market fit for that cohort. If it never flattens, customers never built habits.

  3. 03

    Compare cohorts side by side

    Newer cohorts should have flatter curves than older ones if your retention work is paying off. If cohorts look identical month after month, you have not improved.

  4. 04

    Beware the survivor bias trap

    A 24-month cohort retention number only includes customers who could possibly be retained 24 months. Year-old cohorts can't tell you about your two-year-old churners yet.

  5. 05

    Tie retention back to acquisition channel

    Channels that produce cheap-to-acquire customers often produce poorly-retaining customers. CAC and retention need to be analyzed together, not separately.

Built by the team behind SourceLoop

You drew the curve. SourceLoop tells you which channels deliver the cohort that retains.

SourceLoop dashboard tying acquisition channel to multi-month customer retention

Guide

How to read a retention curve in 30 seconds

Three things to look at

The drop in months 1-3 (how aggressively customers churn early), the flattening point (where the curve levels off, which is where you reached PMF for that cohort), and the flat-floor level (how high the curve plateaus, which is the ceiling on long-term retention). A healthy SaaS curve drops fast in months 1-3, flattens around month 6, and holds 30 to 50 percent long-term. A struggling curve declines linearly past month 12 because customers never form habits.

The math, top to bottom

half_life      = month at which retention = 50%
                 (interpolate between input months)
avg_lifespan   ≈ sum(monthly_retention) for 0..N
                 (good approximation for typical curves)
ltv_multiplier = avg_lifespan
ltv            = arpu * gross_margin * avg_lifespan

The lifespan approximation gets less accurate as time horizons extend (you need to extrapolate the tail), but for 24-month cohorts it's accurate to within 5 percent. Long-tail customers (the ones who stayed 5+ years) drive enormous LTV that 24-month cohorts can't measure yet.

Realistic benchmarks by tier

  • Enterprise SaaS: 12-month retention 90%+, half-life 24+ months, lifespan 60+ months
  • Mid-market SaaS: 12-month retention 80-90%, half-life 12-18 months, lifespan 30-50 months
  • SMB SaaS: 12-month retention 60-80%, half-life 4-8 months, lifespan 18-30 months
  • Self-serve / consumer SaaS: 12-month retention 30-50%, half-life 2-4 months, lifespan 8-15 months
  • Consumer subscription apps: 12-month retention 10-25%, half-life 1-2 months, lifespan 3-8 months
  • Best-in-class SaaS at any tier: curve flattens above 50% by month 6 (truly sticky product)

Why the early-month drop is the most important number

Month 1 retention is the most diagnostic single number in a SaaS retention curve. It tells you whether the user activated. Month 1 below 50% means most signups never get to the value moment. Improvements in onboarding, activation, and time-to- first-value all show up first as month 1 retention lifts. Improvements anywhere else (support, expansion, upsell) compound on whatever month 1 number you have.

Cohort comparison: the right way

If your Q3 cohort has higher month-3 retention than your Q1 cohort, your retention work is paying off. If they're identical, nothing changed. If Q3 is worse, something regressed (a product change, a CAC mix shift, a quality of traffic decline). Cohort-on-cohort comparison is the closest thing to a real-time signal you can get for retention work, and it's why teams that take retention seriously plot every new cohort against the previous one.

Why retention compounds in LTV

Lifespan in the LTV formula is the sum of retention. So a 5 percentage point lift in month-12 retention (from 35% to 40%) doesn't just add 5% to LTV — it adds 5% retained forever, plus 5% more month-13 customers who can churn or renew, plus 5% more month-14 customers, etc. Small retention improvements compound into very large LTV improvements when the time horizon is long. This is why investors look at NRR/GRR before any other SaaS metric.

A worked example

Your cohort retains 70% in month 1, 55% in month 2, 48% in month 3, 42% in month 6, 40% in month 9, 38% in month 12, 35% in month 18, 32% in month 24. Sum across these ~26. Half-life is approximately 2.5 months (interpolating between m2 at 55% and m3 at 48%). Lifespan ~26 months. With $200/month ARPU and 80% gross margin, LTV = $200 × 0.80 × 26 = $4,160. Healthy mid-market SMB territory. Improve month-1 retention from 70 to 80 percent without changing later months and lifespan jumps to ~28 months, LTV to $4,480. A 14 percent point one improvement turned into 8 percent more LTV. Compound improvements is what retention work pays.

FAQ

Cohort retention, FAQ

How does this cohort retention curve generator work?

Enter the percentage of customers retained at each milestone month (month 1, 2, 3, 6, 9, 12, 18, 24). The tool plots the retention curve, calculates half-life (months until 50%), estimated average lifespan (sum of monthly retention), and an LTV multiplier. It compares your curve against typical SaaS, ecommerce subscription, and consumer app benchmarks.

What is a healthy retention curve shape?

The classic 'smile' shape: steep drop in months 1-3, then a flattening curve that approaches a stable floor. The flatter the floor, the better the product-market fit. A linear decline that keeps dropping after month 6 means customers never form habits, which is hard to fix without product changes. A curve that flattens at 30%+ is healthy SaaS territory.

What's a good half-life for SaaS?

Self-serve consumer SaaS: 2 to 4 months. SMB SaaS: 3 to 6 months. Mid-market: 12 to 18 months. Enterprise B2B: 24+ months. Half-life is a quick proxy for product stickiness, but cohort analysis is more nuanced than a single number. A short half-life with a high stable floor is often better than a long half-life with continuous decline.

Why is average lifespan calculated as the sum of retention rates?

It's an approximation. If you keep 70% in month 1, 50% in month 2, 40% in month 3, etc., the expected number of months a random customer stays is approximately 0.7 + 0.5 + 0.4 + ... For an exact calculation you'd need integration of the retention curve, but the sum approximation is accurate to within 5% for typical curves and easier to compute. Some textbooks use 1/(1-retention) instead, which is equivalent for exponential curves but breaks for non-exponential ones.

How is this different from churn rate?

Churn rate is a snapshot ('we lost 5% of customers last month'). Retention curve is the full story ('we lose 30% in month 1, 20% in month 2, then 5%/mo after'). The same blended churn rate can correspond to very different curve shapes, with very different LTV implications. Looking at the curve catches things blended churn hides.

Should I cohort by signup month or by acquisition channel?

Both. By signup month surfaces seasonal effects and product changes (Q1 cohort retains differently than Q3 cohort). By acquisition channel surfaces channel-quality effects (customers from Channel X retain better than Channel Y). Most teams start with signup month, then add channel as a second dimension once that's working.

Is this tool free?

Yes. No signup, no email gate. We host it because the same teams trying to improve cohort retention also need real attribution to know which acquisition channels deliver the customers that actually stick around, which is what SourceLoop does.

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