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100% browser-based · no account · instant answers

Video math, minus
the heavy software

Six free calculators for planning video and subtitle work: file size and bitrate math, aspect-ratio cropping, raw storage estimates, social video length and hook timing, render/export time planning, and a real SRT subtitle timing shifter — all client-side, no uploads to a server.

File size ⇄ bitrateCrop & letterbox mathReal SRT shiftingFree forever
Video File Size & Bitrate CalculatorEnter resolution, frame rate and duration, then either a target bitrate or a target file size — this calculator computes the other value and shows the result in MB and GB against common upload limits like Discord, email and Instagram Reels.Aspect Ratio & Crop CalculatorEnter a source width and height (or pick a preset) and a target aspect ratio to get exact crop dimensions and offset, plus the padded letterbox/pillarbox dimensions if you'd rather keep the full frame.Frame Rate & Raw Storage EstimatorEnter resolution, frame rate, duration and a codec/quality tier to estimate total frame count and expected storage size for production and archive planning, using rough real-world bitrate assumptions per tier.Social Video Length & Retention PlannerPick a platform, enter your planned hook, intro, main content and outro length in seconds, and see whether you're within that platform's limit and recommended sweet spot, plus your hook's share of total runtime.Render/Export Time EstimatorEnter footage duration, resolution, a codec/complexity tier and a hardware tier to get a rough export time estimate in minutes and seconds — a planning number, not a guaranteed render time.SRT Subtitle Timing ShifterPaste or upload .srt subtitle file contents, enter a shift amount in seconds (positive or negative, fractional allowed), and get back every timestamp shifted correctly — with rollover handled and a floor at 00:00:00,000 — ready to download.

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Plan the edit before you open the editor

Start with the video file size & bitrate calculator to hit an upload limit or quality target, then use the aspect ratio & crop calculator to work out crop or padding for a different platform format. The frame rate & raw storage estimator and render/export time estimator help with production and export planning, the social video length & retention planner checks your cut against platform norms, and the SRT subtitle timing shifter fixes out-of-sync captions in seconds.

More tools

Video File Size & Bitrate CalculatorEnter resolution, frame rate and duration, then either a target bitrate or a target file size — this calculator computes the other value and shows the result in MB and GB against common upload limits like Discord, email and Instagram Reels.Aspect Ratio & Crop CalculatorEnter a source width and height (or pick a preset) and a target aspect ratio to get exact crop dimensions and offset, plus the padded letterbox/pillarbox dimensions if you'd rather keep the full frame.Frame Rate & Raw Storage EstimatorEnter resolution, frame rate, duration and a codec/quality tier to estimate total frame count and expected storage size for production and archive planning, using rough real-world bitrate assumptions per tier.Social Video Length & Retention PlannerPick a platform, enter your planned hook, intro, main content and outro length in seconds, and see whether you're within that platform's limit and recommended sweet spot, plus your hook's share of total runtime.Render/Export Time EstimatorEnter footage duration, resolution, a codec/complexity tier and a hardware tier to get a rough export time estimate in minutes and seconds — a planning number, not a guaranteed render time.SRT Subtitle Timing ShifterPaste or upload .srt subtitle file contents, enter a shift amount in seconds (positive or negative, fractional allowed), and get back every timestamp shifted correctly — with rollover handled and a floor at 00:00:00,000 — ready to download.

Frequently asked questions

Is ClipKit really free, with no account needed?

Yes — every tool runs entirely in your browser with no sign-up, no data collection and no cost. Nothing you type, paste or upload is sent to a server.

Who is ClipKit built for?

Video editors, YouTubers, social media creators and anyone planning video or subtitle work who wants quick math on file size, aspect ratio, storage, length limits, export time or subtitle timing without opening heavy editing software.

How accurate are the file size, storage and export time estimates?

They're planning estimates built on commonly used bitrate and processing-speed assumptions, not exact measurements of any specific encoder or machine. Real-world results vary with content complexity, software and hardware — use these numbers to plan, then confirm with your own export.

Does the SRT subtitle shifter actually work, or is it just a mockup?

It's a real, fully functional tool — it parses genuine .srt timestamp syntax, shifts every timestamp by your chosen amount with correct rollover and zero-clamping, and lets you download the corrected file, all client-side.