---
title: "DNA molarity calculator"
method: POST
path: "/dna_molarity"
tags: ["Primers & oligos"]
---

# DNA molarity calculator

`POST /dna_molarity`

## Request

- Base URL: `https://seqbench.com/api/v1`
- URL: `https://seqbench.com/api/v1/dna_molarity`
- Auth: none required

Nucleic-acid quantity conversions: molar mass, amount (pmol/nmol), molar and mass concentration, and copy number, from mass ± volume and either a length or a sequence.

Batchable via `POST /batch`.

## Request body

- object
  - `type` 'dsDNA' | 'ssDNA' | 'ssRNA': Molecule type.
  - `length` integer: Length in bp (dsDNA) or nt (ssDNA/ssRNA). Ignored when a sequence is given.
  - `massNg` number: Mass in nanograms.
  - `volumeUl` number: Volume in microlitres (0 = unknown; needed for concentration).
  - `sequence` string: Optional sequence — overrides length and gives an exact molar mass from base composition.
  - `targetConcentration` number: Optional: the concentration you need. Supplying it (with volumeUl, so there is a stock concentration to dilute FROM) returns a `dilution` plan — µL of stock and µL of diluent — instead of leaving C1V1 = C2V2 to be done by hand. The stock and the target may be quoted in different units; the molar mass converts between them.
  - `targetUnit` 'nM' | 'uM' | 'ngPerUl': Unit for targetConcentration.
  - `targetVolumeUl` number: Final volume of the diluted sample, in µL.

## Response `200`

Tool ran successfully.

- SuccessResponse: Standard success envelope returned by every single-tool call.
  - `ok` unknown, required
  - `tool` string, required: The tool slug that ran.
  - `result` object, required: Tool-specific output object. Its shape depends on the tool — call `GET /{tool}` or see the docs for each tool's fields.
  - `gate` GateResult
    - `pass` boolean, required: True if and only if every hard check passed.
    - `checks` GateCheck[], required
      - `id` string, required
      - `label` string, required
      - `severity` 'hard' | 'soft', required
      - `pass` boolean, required
      - `message` string, required
      - `value` number
      - `threshold` string
    - `notChecked` string[], required: Honest list of what this gate does NOT verify.
  - `provenance` Provenance, required
    - `apiVersion` string, required
    - `tool` union, required: Tool slug, or an array of slugs (one per step) for a workflow.
      - string
      - string[]
    - `generatedAt` string, date-time, required: ISO 8601 timestamp of when the result was generated.

## Other responses

- `400`: Invalid argument or the tool could not run.
- `404`: Unknown tool.
- `429`: Rate limited (metered tools only). Body carries code `rate_limited` and retryable `true`; honor the Retry-After header.
- `503`: A metered tool is momentarily at capacity. The identical request should succeed after Retry-After; body carries code `upstream_unavailable`.

---

[API](https://skmtc.dev/seqbench/apis/seqbench-api.md) · [All operations](https://skmtc.dev/seqbench/apis/seqbench-api/llms.txt) · [OpenAPI document](https://skmtc.dev/seqbench/apis/seqbench-api/revisions/132575216865?raw)