Churn Impact Calculator

Every month, churn removes customers and recurring revenue before new sales count. At 4% monthly churn on 1,000 customers, you lose 40 accounts before measuring growth — acquisition must replace them just to stand still.

This calculator estimates customers lost, revenue lost, and net customer change given new sign-ups.

Use the cohort retention churn curve calculator when the question is month-by-month cohort decay, NRR, expansion, downgrades, and retention curves rather than one current churn rate.

Every month churn removes customers and recurring revenue before new sales count. At 4% monthly on 1,000 customers, you lose 40 accounts before measuring growth.

Use with cohort retention churn curve calculator when retention shape matters, and LTV vs CAC breakeven calculator when retention improvements need to support acquisition payback.

Lost customers = 40 per month. At £35 revenue per user, that is £1,400 monthly recurring revenue at risk.

With 55 new customers, net change is +15 customers — growth looks positive but 40 sales only replaced leavers plus a small net.

Cutting churn from 4% to 3% saves 10 customers and £350 MRR monthly — often cheaper than buying 10 extra leads.

Lost customers = 40 per month. At £35 revenue per user, £1,400 monthly recurring revenue at risk.

With 55 new customers, net change is +15 — growth looks positive but 40 sales replaced leavers first.

Cutting churn from 4% to 3% saves 10 customers and £350 MRR monthly — often cheaper than 10 extra CAC purchases.

Compare cost to save one customer vs CAC for a new one. Retention improvements compound because saved customers keep paying and refer.

Segment churn — voluntary vs payment failure — fixes differ.

When net MRR growth flatlines despite rising new logos.

When CAC payback lengthens because customers leave before LTV materialises.

After product or pricing changes — churn often spikes one to two cohorts later.

Celebrating gross adds while net MRR flatlines. Using annual churn percentage without converting to monthly for operational planning.

Ignoring downgrades as partial churn when revenue per user falls.

Using annual churn % in a monthly model — 5% annual is not 5% monthly.

Celebrating gross adds while net MRR is flat — logo churn hides in top-line acquisition charts.

Ignoring involuntary churn (failed payments) — fix billing before blaming product retention.

Customers lost = current customers × (churn rate ÷ 100). Revenue lost = customers lost × revenue per user. Net customer change = new customers − customers lost.

Logo churn and revenue churn differ if downgrades happen — this model uses count and average revenue per user.

Annualise carefully: 4% monthly churn is far more severe than 4% annual — use consistent periods.

Onboarding that reaches first value quickly.

Proactive support for at-risk usage patterns.

Annual contracts with sensible discounts.

Expansion revenue so downgrades hurt less.

Fix payment failure churn separately from voluntary churn.

If 40 customers churn monthly at £35 ARPU, you lose £1,400 MRR before net growth — acquiring 40 replacements at £200 CAC costs £8,000 that month just to stand still.

Cutting churn from 4% to 3% on 1,000 customers saves 10 logos and £350 MRR — often cheaper than 10 extra paid acquisitions.

Pair with LTV vs CAC breakeven calculator — retention improvements raise LTV and improve ratio without raising ad spend.

Report customers lost and MRR lost alongside new logos — net change tells true growth.

Fix involuntary churn (billing failures) before blaming product — quick win often available.

Feed improved retention into LTV calculator before raising CAC targets.

Losing 12 customers at £400/month MRR is £4,800 MRR gone — but if those accounts were on legacy pricing at £250/month while new sales average £550, the revenue impact understates strategic damage: you may be replacing high-value accounts with cheaper ones even when net customer count grows.

Separate voluntary churn (product, price, fit) from involuntary (card failures, expired trials) — involuntary often responds to billing retries and dunning before roadmap work, and can represent 15–30% of gross churn in SMB SaaS.

Model annualised revenue lost as MRR lost × 12 for board conversations, then layer expansion revenue from retained cohorts — net revenue retention above 100% means churn is offset by upsell, but only if expansion is tracked on the same base.

After any retention initiative, rerun LTV vs CAC breakeven calculator with updated churn — a 2 point retention improvement can matter more than a 10% CAC cut for payback period.

Set a churn review cadence: weekly for early-stage (<£1M ARR), monthly once processes stabilise — waiting for quarterly board packs lets small leaks become structural holes.

Company-wide churn can look stable while newer cohorts churn at 2× the rate of older ones — use the cohort retention churn curve calculator to segment by signup month before blaming market conditions.

Compare logo churn to revenue churn when downgrades are common — you may retain accounts while losing MRR, which LTV calculator captures better than a simple customer count.

This page should target churn impact calculator, monthly churn calculator, SaaS churn revenue loss, customer churn cost, and retention revenue impact searches.

It calculates customers lost, revenue lost, and net customer change from current customers, monthly churn rate, revenue per user, and new customers. It does not calculate cohort retention curves, net revenue retention, expansion revenue, downgrades by plan, involuntary churn workflows, or annual-to-monthly churn conversion automatically. Use cohort retention churn curve calculator for cohort-level retention and NRR.