JWT exp Days-Left Converter

Convert a supplied JWT exp NumericDate and reference NumericDate into signed fractional days remaining and expiry status.

Description

A JWT exp claim is a NumericDate measured in seconds since the Unix epoch.

A JWT exp claim is a NumericDate measured in seconds since the Unix epoch. The difference from a supplied reference time can be expressed in fractional days, with equality at expiration already treated as expired.^{[1, 2]}

Convert a supplied JWT exp NumericDate and reference NumericDate into signed fractional days remaining and expiry status.

When to use JWT exp Days-Left Converter

Use this tool to convert a supplied JWT exp NumericDate and reference NumericDate into signed fractional days remaining and expiry status.

Choose the text, counts, explicit reference time or format parameters requested by this tool. Follow the stated byte, epoch-time and randomness assumptions.

How to use JWT exp Days-Left Converter and understand its results

Choose the text, counts, explicit reference time or format parameters requested by this tool. Follow the stated byte, epoch-time and randomness assumptions.
Enter expiration, now using the field table and calculation rules, then run the tool.
Read daysLeft, expired. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
expiration	Expiration NumericDate	number	Required
now	Reference NumericDate	number	Required

Enter finite expiration and now values in epoch seconds; fractional seconds and negative dates are accepted. The tool subtracts and converts to days, trying a divided-first expression if subtraction overflows. Positive daysLeft means time remains, zero marks the boundary, and negative values mean elapsed expiration. An irrecoverably nonfinite difference is an error.

daysLeft = (expiration − now)/86,400; expired = now ≥ expiration

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
daysLeft	Fractional days remaining	number
expired	Expiration reached	boolean

json

{
  "input": {
    "expiration": 259200,
    "now": 86400
  },
  "output": {
    "daysLeft": 2,
    "expired": false
  }
}

Limitations and assumptions

It does not decode a JWT, verify a signature, check issuer/audience or read the clock. There is no clock-skew leeway, and a future exp does not establish token validity. Do not supply epoch milliseconds without conversion.

Numeric inputs must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.

Alternative or Complementary methods

Use TOTP Step Remaining Seconds: Calculate the TOTP moving counter and whole seconds remaining in its current time step from explicit epoch seconds. For a complementary task, use Certificate Validity Days Left: Classify an explicitly supplied certificate validity interval and calculate fractional days until notAfter using epoch milliseconds.

Further background: RFC 7519: JWT NumericDate and expiration claim.

References

JWT exp Days-Left Converter — tool.io
RFC 7519: JWT NumericDate and expiration claim — RFC Editor

Similar or alternative tools

TOTP Step Remaining Seconds
Calculate the TOTP moving counter and whole seconds remaining in its current time step from explicit epoch seconds.
Certificate Validity Days Left
Classify an explicitly supplied certificate validity interval and calculate fractional days until notAfter using epoch milliseconds.