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Timecode Calculator

Add and convert HH:MM:SS:FF timecodes for film, TV, and video work, with frame-accurate results at standard editing rates.

Mode

Use HH:MM:SS:FF or HH:MM:SS;FF.

Result

17,982 frames

00:10:00;00 at 29.97 DF equals 17,982 frames.

Quick Answer

A timecode calculator turns each HH:MM:SS:FF value into a frame count. It does the math, then turns the answer back into timecode at the chosen rate. At 30 fps, 01:12:30:10 plus 00:00:45:20 equals 01:13:16:00 because 30 frames make one second.

How Frame Accurate Timecode Math Works In Video Edits

A timecode calculator works with hours, minutes, seconds, and frames. The last field is a frame count, not a decimal part of a second. The chosen rate tells the tool how many frame labels fit within each second. For 24, 25, and 30 fps, the tool changes each value to total frames, does the math, and then returns an HH:MM:SS:FF result. The 29.97 modes need one extra choice. Non-drop-frame timecode counts labels in a steady 30-label pattern, so the display slowly moves away from clock time. Drop-frame timecode skips certain frame numbers to reduce that drift. The video frames stay in place. Only the labels change. This difference matters most during long shows and broadcast work, where clock time matters.

The Timecode Frame Count Formula And Rate Match Rule

For whole-number frame rates, the tool converts each timecode to total frames, does the arithmetic, then converts the result back to HH:MM:SS:FF.

  • Total seconds = hours × 3,600 + minutes × 60 + seconds
  • Total frames = total seconds × frame rate + frame field
  • Add or convert the total frame counts.
  • Convert the final frame count back to HH:MM:SS:FF.

How To Use A Timecode Calculator In Four Clear Steps

Inputs

  • Operation: choose timecode addition or conversion.
  • Frame rate: select 24, 25, 30, 29.97 NDF, or 29.97 DF.
  • Start timecode: enter the first HH:MM:SS:FF value.
  • Duration or second value: enter the timecode to add or convert.

Steps

  1. Select the operation and the correct frame rate.
  2. Enter each value in HH:MM:SS:FF form.
  3. Check that DF or NDF matches the source.
  4. Read the result and confirm the frame field.

Broadcast Timecode Example With Every Frame Step Shown

Add a clip duration of 00:00:45:20 to a start timecode of 01:12:30:10 at 30 fps (non-drop).

  1. Start seconds: 1 × 3,600 + 12 × 60 + 30 = 4,350 seconds.
  2. Start frames: 4,350 × 30 + 10 = 130,510 frames.
  3. Duration frames: 45 × 30 + 20 = 1,370 frames.
  4. Combined frames: 130,510 + 1,370 = 131,880 frames.
  5. Convert back: 131,880 ÷ 30 = 4,396 seconds with 0 frames left.
  6. 4,396 seconds = 1 hour, 13 minutes, 16 seconds.

01:13:16:00. No rounding is needed because the result uses whole frames.

When A Timecode Tool Helps With Edit And Sync Work

Use the tool for clip end points, edit notes, show lengths, and sync checks. Long timelines make manual carries easy to miss. Match the rate and DF or NDF mode before copying the answer into an edit system.

For more time tools, see the time and date calculators hub or look up timecode terms in the glossary.

Assumptions

  • Each value follows HH:MM:SS:FF form.
  • The selected rate matches the source and sequence.
  • The frame field is valid for the chosen rate.
  • Drop-frame mode follows the SMPTE label rule.
  • The calculation uses frame counts, not decimal seconds.

Limitations

  • The tool cannot detect the frame rate from typed numbers.
  • DF and NDF values need a common basis before addition.
  • Audio samples and subframes are outside this tool's scope.
  • Variable frame rate media needs another timing method.
  • A production system may wrap timecode after 24 hours.

In Practice

Many editors think drop-frame removes video frames. It does not. The rule skips frame numbers only. Match DF or NDF to the timeline before you add or convert a timecode.

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Related Guides

Frequently Asked Questions About Video Timecode Math

What Does HH MM SS FF Mean In Timecode?

HH:MM:SS:FF means hours, minutes, seconds, and frames in a video timecode value. The frame field counts images within the current second under the chosen rate. At 25 fps, valid frame labels run from 00 through 24.

Does Drop Frame Timecode Remove Video Frames?

Drop-frame timecode does not remove any recorded or played video frames from the clip. The rule skips selected frame numbers in the label count at 29.97 fps. The picture sequence still includes every frame.

What Is The Difference Between 29.97 DF And NDF?

Both modes describe video running at 30000/1001 frames per second, often called 29.97 fps. NDF keeps a steady label count but drifts from clock time. DF skips labels under a set rule to stay closer to elapsed time.

Can You Add Timecodes With Different Frame Rates?

Timecodes at different frame rates need conversion to one common rate before addition. The FF field only makes sense at its stated rate. Adding the shown fields as plain numbers can place an edit on the wrong frame.

Sources

Last updated: . Reviewed for accuracy against the formula shown above.