# MRR Growth Calculator

> Projects monthly recurring revenue after n months of compound growth from a starting MRR and a monthly growth rate (given directly or derived from new, expansion and churned MRR), and reports the resulting ARR, total growth, the equivalent annual growth rate and the doubling time.

- Calculator id: `mrr-growth` · Category: Business & Marketing (`business`) · Tool name: `predict_mrr_growth`
- Canonical page: https://tttkmbb.com/business/mrr-growth · This document: https://tttkmbb.com/business/mrr-growth.md · JSON definition: https://tttkmbb.com/business/mrr-growth.json

## Purpose

Projects monthly recurring revenue after n months of compound growth from a starting MRR and a monthly growth rate (given directly or derived from new, expansion and churned MRR), and reports the resulting ARR, total growth, the equivalent annual growth rate and the doubling time.

**Use when:** You run a subscription business and want to see where MRR lands after a number of months at the current growth rate, or convert a monthly rate into an annual one.

**Do not use when:** Growth is in absolute amounts rather than a percentage each month (use a linear projection), or you need customer-count churn (use churn-rate) or unit economics (use cac-ltv).

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `starting_mrr` | number |  | required | Current monthly recurring revenue. (min 0, max 1000000000000) |
| `monthly_growth_percent` | number | % | optional | Net MRR growth per month in percent. If omitted, it is derived from new_mrr + expansion_mrr − churned_mrr relative to starting_mrr. (min -100, max 1000) |
| `new_mrr` | number |  | optional | MRR added from new customers in a typical month (used when monthly_growth_percent is omitted). (min 0, max 1000000000000) |
| `expansion_mrr` | number |  | optional | MRR added from upgrades of existing customers. (min 0, max 1000000000000) |
| `churned_mrr` | number |  | optional | MRR lost from cancellations and downgrades. (min 0, max 1000000000000) |
| `months` | integer | months | optional, default 12 | Projection horizon. (min 1, max 600) |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `monthly_growth_rate_percent` | number | % | Rate used for the projection. |
| `net_new_mrr_first_month` | number |  | starting_mrr × growth rate (or new + expansion − churned). |
| `mrr_after` | number |  | starting_mrr × (1 + g)^months. |
| `arr_after` | number |  | mrr_after × 12. |
| `total_growth_percent` | number | % | ((1 + g)^months − 1) × 100. |
| `annualized_growth_percent` | number | % | ((1 + g)^12 − 1) × 100: the CAGR equivalent of the monthly rate. |
| `months_to_double` | number | months | ln 2 / ln(1 + g) (only when g > 0). |

## Formula

`g = monthly_growth_percent/100 or (new_mrr + expansion_mrr − churned_mrr) / starting_mrr; MRR_n = starting_mrr × (1 + g)^months; ARR = 12 × MRR_n; annualised = (1 + g)^12 − 1; months_to_double = ln 2 / ln(1 + g)`

Compound projection at a constant monthly rate; when the rate is derived from MRR components, the same percentage (not the same currency amount) is assumed for every month.

## Data Sources

- Wikipedia – Compound annual growth rate — https://en.wikipedia.org/wiki/Compound_annual_growth_rate (reference, retrieved 2026-09-24)
- Andreessen Horowitz – 16 Startup Metrics — https://a16z.com/16-startup-metrics/ (reference, retrieved 2026-09-24)

Data freshness: `static`. Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output.

## API

- `GET https://tttkmbb.com/api/v1/calculate/mrr-growth?starting_mrr=…`
- `POST https://tttkmbb.com/api/v1/calculate/mrr-growth` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/mrr-growth · OpenAPI operationId `predict_mrr_growth` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool:  `run_calculator` with `{"calculator_id": "mrr-growth", "inputs": {…}}`

## Example

- 10,000 MRR at 5 %/month for 12 months: inputs `{"starting_mrr":10000,"monthly_growth_percent":5,"months":12}` → `{"monthly_growth_rate_percent":5,"net_new_mrr_first_month":500,"mrr_after":17958.56,"arr_after":215502.76,"total_growth_percent":79.59,"annualized_growth_percent":79.59,"months_to_double":14.21}`
- 20,000 MRR, +1,500 new, +500 expansion, −800 churned, 6 months: inputs `{"starting_mrr":20000,"new_mrr":1500,"expansion_mrr":500,"churned_mrr":800,"months":6}` → `{"monthly_growth_rate_percent":6,"net_new_mrr_first_month":1200,"mrr_after":28370.38,"arr_after":340444.59,"total_growth_percent":41.85,"annualized_growth_percent":101.22}`

```
GET https://tttkmbb.com/api/v1/calculate/mrr-growth?starting_mrr=10000&monthly_growth_percent=5&months=12
```

## Limitations

Growth is in absolute amounts rather than a percentage each month (use a linear projection), or you need customer-count churn (use churn-rate) or unit economics (use cac-ltv). Compound projection at a constant monthly rate; when the rate is derived from MRR components, the same percentage (not the same currency amount) is assumed for every month. All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**Why is 5 % monthly not 60 % yearly?**

Growth compounds: 1.05^12 = 1.796, so 5 % per month is 79.6 % per year. The often-quoted 'T2D3' path corresponds to roughly 10 % monthly growth in the early years.

**What is net new MRR?**

New MRR from new customers plus expansion MRR from upgrades minus churned and contraction MRR. Divided by starting MRR it gives the net monthly growth rate used here.

## Related

- [CAGR Calculator](https://tttkmbb.com/finance/cagr.md) — Annual growth rate between two values.
- [Churn Rate Calculator](https://tttkmbb.com/business/churn-rate.md) — Customer-count churn behind churned MRR.
- [Compound Interest Calculator](https://tttkmbb.com/finance/compound-interest.md) — Same compounding arithmetic for money.