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Add time calculator

Add two durations in hours, minutes and seconds with the carries done for you: 1:45:40 plus 2:30:35 is 4:16:15, because extra minutes and seconds roll over at 60. Hours keep counting past 24. Free in your browser.

  • Free
  • Runs in your browser
  • No sign-up
  • Your data stays on your device
Run — free How it works & API
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Run — free

Worked example

If you enter
Hours a
1
Minutes a
45
Seconds a
40
Hours b
2
Minutes b
30
Seconds b
35
You get
Hours
4
Minutes
16
Seconds
15
Total seconds
15,375

Adding two clock-style durations looks simple until minutes and seconds overflow sixty. A first clip of one hour forty-five minutes and forty seconds plus a second clip of two hours thirty minutes and thirty-five seconds is not three hours seventy-five minutes and seventy-five seconds — it is four hours sixteen minutes and fifteen seconds after the carries. This add-time calculator accepts two durations as integer hours, minutes, and seconds, converts each to a total second count, adds those totals, and returns the sum normalized so minutes and seconds each sit in the range 0–59 while hours may grow without a twenty-four-hour wrap.

How two durations become one normalized total

A duration is a length of time, not a clock reading on a twelve-hour or twenty-four-hour face. When you add one hour forty-five minutes and forty seconds to two hours thirty minutes and thirty-five seconds you first convert each operand to seconds: the first duration is six thousand three hundred forty seconds and the second is nine thousand thirty-five seconds. Their sum is fifteen thousand three hundred seventy-five seconds.

Dividing by three thousand six hundred yields four whole hours with nine hundred seventy-five seconds remaining; dividing that remainder by sixty yields sixteen minutes with fifteen seconds left. The normalized result is therefore four hours, sixteen minutes, and fifteen seconds. Minutes or seconds that arrive already above fifty-nine are legal inputs because this tool is a duration adder, not a clock validator: seventy minutes is simply four thousand two hundred extra seconds, and ninety seconds is an extra minute and a half.

After the total is formed, minutes and seconds are always reduced into the conventional zero-to-fifty-nine range. Hours are not wrapped at twenty-four, because twenty-five hours of work is twenty-five hours, not one o'clock the next day. The algorithm never consults the system clock, never calls a network service, and never uses randomness, so the same pair of durations always produces the same total.

Where an add-time calculator earns its keep

People reach for an add-time calculator whenever two stopwatch readings must become one total. Video editors add scene lengths to confirm a cut still fits a slot. Podcasters sum intro and interview blocks before they publish a show note that quotes runtime.

Payroll clerks add ordinary hours to overtime minutes that arrived as a second pair rather than as a decimal. Sports coaches combine drill blocks and rest intervals to print a session card. Project managers add two task estimates that were recorded as hours, minutes, and seconds instead of a single decimal hour.

Teachers demonstrate carrying in sexagesimal arithmetic without forcing students to do the three-thousand-six-hundred and sixty conversion by hand. Because hours do not wrap at midnight, the same tool also totals multi-day work or travel time: forty hours plus eight hours is forty-eight hours, not a clock time of midnight. Pair this page with a later subtract-time or convert-to-seconds step if your workflow also needs differences or a raw second count for a timesheet system.

What you can do with it

Video and podcast runtimes

Add two clip or segment lengths given as hours, minutes, and seconds to confirm the combined runtime still fits a slot or a published show note.

Timesheets and overtime

Sum regular hours with an overtime block that arrived as a second HMS pair, without wrapping at midnight or converting to decimal hours first.

Classroom sexagesimal carrying

Let students check that seventy minutes plus ninety seconds normalizes to one hour eleven minutes thirty seconds instead of an illegal clock face.

FAQ

What happens if minutes or seconds are greater than 59?

They are accepted. This is a duration adder, not a clock-face validator. Extra minutes and seconds are carried into hours when the total is normalized.

Why are negative components rejected?

A duration in this contract cannot contain a negative clock field.

Do hours wrap at 24?

No. Hours stay unbounded so twenty-five hours plus one hour is twenty-six hours, not two o'clock. Use a clock or calendar tool if you need a time of day.

Is adding durations the same as adding hours to a clock time?

No. This tool adds lengths of time, like two video clips or two work blocks, so the hours never wrap at midnight. To move a clock reading forward, such as a start time, you need a clock-time calculator instead.

Can I enter a decimal value such as 1.5 hours?

No. Each part must be a whole, non-negative number of hours, minutes or seconds. Enter one and a half hours as 1 hour and 30 minutes instead, and the total will be carried correctly.

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For developers — API access

Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.

API endpoint

POSThttps://api.kit.forhosting.com/life/add-time

Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.

Call it from your stack

curl -X POST https://api.kit.forhosting.com/life/add-time \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"hours_a":1,"minutes_a":45,"seconds_a":40,"hours_b":2,"minutes_b":30,"seconds_b":35}'

Example request

{
  "hours_a": 1,
  "minutes_a": 45,
  "seconds_a": 40,
  "hours_b": 2,
  "minutes_b": 30,
  "seconds_b": 35
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "life.add_time",
  "status": "queued",
  "_links": {
    "result": "/tasks/tsk_…/result"
  }
}

The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.

Pricing

Per request$0.002

Published price — no tokens, no invented credits. A failed task is never charged.

Limits

max_component1000000000000

Errors

HTTPCodeMeaning
401unauthorizedMissing or invalid API key.
402insufficient_balanceYour balance doesn't cover the task price.
404unknown_typeThat task type doesn't exist.
429rate_limitedToo many requests. Use the webhook instead of polling.

Technical notes

Negative components and non-integers are rejected with invalid_input because a duration in this contract cannot contain a fractional or negative clock field.

Input contract, response shape, and error behaviour

Every field is required. A negative component also fails, because a duration in this contract cannot contain a negative clock part; the error message states that the field must be a non-negative integer. Whole numbers written as decimal-free numeric strings are accepted so forms and CSV pipelines can post text. Invalid input is not billed. The request body carries six integer fields: hours_a, minutes_a, and seconds_a for the first duration, and hours_b, minutes_b, and seconds_b for the second. A missing field, an empty string, a boolean, a fractional number such as one point five, or a non-numeric string fails with invalid_input and names the offending field. On success the response echoes a normalized breakdown: hours unbounded by midnight, minutes in zero to fifty-nine, seconds in zero to fifty-nine, total_seconds as the exact integer sum, a pretty string formatted as hours colon minutes colon seconds with zero-padded minutes and seconds, and a short formula string you can show next to the answer. Successful API calls use the published $0.002 base price.

Where an add-time calculator earns its keep

That keeps latency at a few arithmetic operations and keeps the cost model honest at $0.002 per successful API request, while failed validation never consumes prepaid balance.

Technical questions

How do I add two times in hours, minutes, and seconds?

Send six non-negative integers: hours_a, minutes_a, seconds_a and hours_b, minutes_b, seconds_b. The API converts each duration to seconds, adds them, and returns hours plus minutes and seconds normalized into 0–59.

What does the add-time calculator cost?

The browser tool is free. API requests use prepaid balance at $0.002 per successful call; invalid input is not billed.

Read the full KIT documentation →