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Spot gap magnitude and direction instantly, then dig into catalyst context.

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Gap Up / Gap Down Calculator

Calculate the opening gap versus previous close.

Quantify overnight gap behavior by comparing today’s open (or current premarket price) with yesterday’s close.

Inputs

Results

Gap

+3.00%

Opening gap is +$3.00 (+3.00%).

Previous close
$100.00
Open / current
$103.00
Gap amount
+$3.00
Direction
Gap Up

Formula

Gap % = ((Open Price - Previous Close) / Previous Close) × 100

Example

  • Previous close: 100
  • Open / current: 103

What does this mean?

  • •Gap up means open is above previous close.
  • •Gap down means open is below previous close.
  • •Large gaps often require catalyst review (earnings, guidance, macro, filings).

Track gaps before the crowd reacts

Spot gap magnitude and direction instantly, then dig into catalyst context.

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What is a gap up / gap down?

Quantify overnight gap behavior by comparing today’s open (or current premarket price) with yesterday’s close. In practice, this means you can quantify gap up / gap down using previous close, and open / current without relying on hidden assumptions or black-box scoring.

Primary input set for this calculator: Previous close, Open / current.

How to calculate gap up / gap down

  1. 1.Step 1: Enter previous close with the timeframe/context you want to evaluate.
  2. 2.Step 2: Enter open / current with the timeframe/context you want to evaluate.
  3. 3.Step 3: Apply formula Gap % = ((Open Price - Previous Close) / Previous Close) × 100.
  4. 4.Step 4: Interpret output together with risk, liquidity, and catalyst context.

Why this metric matters

This metric standardizes raw price action so you can compare moves across different tickers, sessions, and catalyst windows.

Pair this calculator with catalyst context from headlines, filings, and options flow to avoid relying on isolated numbers.

When to use this calculator

  • ✓Before opening a new position where gap up / gap down impacts sizing or risk.
  • ✓After a catalyst to quantify how much conditions changed versus your baseline.
  • ✓When comparing setups across multiple tickers with one consistent formula.
  • ✓During weekly review to keep decision-making tied to measurable inputs.

Common scenarios

Gap up means open is above previous close

Use this gap up / gap down workflow to quantify this scenario with deterministic inputs.

Gap down means open is below previous close

Use this gap up / gap down workflow to quantify this scenario with deterministic inputs.

Large gaps often require catalyst review (earnings, guidance, macro, filings)

Use this gap up / gap down workflow to quantify this scenario with deterministic inputs.

Event reaction review

Recalculate gap up / gap down immediately after earnings, filings, or macro headlines.

Interpretation tips

  • •Re-run gap up / gap down whenever key inputs change materially, not only when price moves.
  • •Document assumptions so the same methodology can be repeated across watchlist names.
  • •Use this metric as one layer in the decision stack, not as a standalone trade trigger.

Data caveats

  • –Outputs are deterministic from your inputs; input quality determines output quality.
  • –This page does not auto-adjust for broker fees, taxes, or slippage unless you include them in your assumptions.
  • –Validate corporate action details, filing dates, and data freshness before acting on results.

FAQ

How does the gap up / gap down calculator work?

Gap Up / Gap Down Calculator is deterministic and uses only your inputs (previous close, open / current). Formula: Gap % = ((Open Price - Previous Close) / Previous Close) × 100.

What does this output tell me in practice?

Calculate the opening gap versus previous close. Pair this with a stop-loss and thesis review, not just return math.

Does the gap up / gap down calculator use real-time market feeds?

No. This page does not auto-pull live data. You control all inputs and can rerun instantly as market conditions change.

Can I use this result directly for trading decisions?

Use it as a planning layer. Combine with position sizing, liquidity, and catalyst context before any execution.

Disclaimer: This calculator is for educational purposes and does not constitute financial advice. Verify assumptions with official filings, broker statements, and your own risk framework.