How to Read a Recessed Lighting Spec Sheet

What the Calculator Needs—and What a Spec Sheet Actually Means

The calculator requires per-fixture lumens and beam angle; fixture watts are optional. Use verified values for the selected configuration. If its lumen output or beam angle is missing, obtain the exact product’s photometric data before treating the estimate as a plan for that fixture. Do not substitute a trim diameter, LED-chip claim, color temperature or CRI for any of those fields.

A default or previously entered beam angle is a model assumption, not verified data for your new SKU. Clearing the required field does not mean “unknown”: on leaving it blank, the calculator restores its previous valid angle.

“Per fixture” matters. A carton total, two-head kit or remote driver package is not automatically the output of one installed downlight. If the document does not identify the measurement basis, record the gap in your project notes and ask the manufacturer, seller or installer for the exact product documentation.

A missing beam angle may be a report-type issue: integrating-sphere-only LM-79 measurements do not describe angular light distribution. Request matching angle-resolved photometry for the exact model and setting. DOE’s report-reading explanation (2012) distinguishes the measurement methods.

Read the Sheet in a Repeatable Order

Treat the ordering table and the photometric table as a join: first name the configuration, then take numbers from the matching tested row. A series name alone is not a complete fixture identity.

1. Capture the complete ordering code. Record the base model plus lumen package, CCT, optic, finish, voltage/driver and any suffix that changes output or distribution. A switchable setting still needs the setting you will actually use.
2. Read the condition next to the numbers. Check whether the row states CCT, optic, input voltage, test file or other condition. Keep that condition with the values in your project notes.
3. Copy only matched calculator fields. Put the tested lumens and beam angle into their required fields, with input watts if known. If the matching beam angle is absent, request the exact photometric data; do not adopt a default or a neighboring row simply to finish the form.
4. Run a separate fit-and-safety check. Read cutout, ceiling thickness/depth, housing compatibility, location rating, insulation instructions and dimmer list as installation constraints—not calculator inputs.

Worked Example: One Reported Photometric Configuration

HALO’s current LT56 Selectable LED Trim sheet reports a photometric row for LT56079FS1EWHR at 3000 K: 795 lumens, 8.6 input watts and a 95.7° beam angle. Those three values can be copied into the calculator only when that model and the 3000 K condition match the installed fixture.

Beam angle and field angle commonly use 50% and 10% of maximum luminous intensity, respectively. They are full angular widths, not hard edges beyond which no light is emitted; follow the report’s stated intensity reference. Zonal lumens split output into angular zones rather than define a beam angle.

The same row also reports a spacing criterion (SC), a dimensionless spacing-to-mounting-height ratio. For a regular grid of the same fixture at one mounting height, estimated maximum recommended spacing is SC × height above the workplane. This guides workplane illuminance uniformity—not a required spacing or a guarantee of target illuminance; check light count and maintained average illuminance separately. A report may give different values for two perpendicular axes; use the applicable value for each direction and fixture orientation. The calculator’s fixed spacing ratio of 1.5 is a planning assumption, not this fixture’s manufacturer SC. AGi32 explains the axis-specific spacing check.

The ordering table’s nominal 750-lumen package and its 8.75 W energy figure are not the 795 lm / 8.6 W values in this tested 3000 K photometric row. Do not mix those distinct document entries into one calculator configuration. The same PDF also contains a separate 22CZ2 photometric block; it is excluded here because its model string does not match LT56079FS1EWHR.

Primary source: HALO LT56 Selectable LED Trim spec sheet (official PDF, June 16, 2026), photometric entry for the model and 3000 K condition above; accessed October 5, 2026. The manufacturer’s LT56 product page separately identifies the document as its spec sheet. The page preserves the model string and condition so the values are not presented as a family-wide promise.

Why a Series Name Is Not Enough

A series can branch into different outputs, CCT selections, beam distributions, trims, drivers and voltage options. Bind the row to a concrete SKU and setting before using a number. If a sheet lists several choices but does not publish all three calculator inputs for your exact choice, record the missing field as not provided.

A selectable-CCT or adjustable-lumen fixture may publish output at multiple settings. The switch position you plan to use is part of the configuration. Do not average numbers across positions. If an online listing and the official spec sheet disagree, use the current official document for the exact model or pause the entry until the discrepancy is resolved.

Keep These Important Specifications Out of the Calculator

Cutout, trim/aperture, housing depth, ratings and dimming are all important—but they answer fit, safety or control questions. They do not establish the room size or the fixture output used by this calculator.

For the installed system, compare housing-based and canless maintenance paths. For labels, use the IC marking and complete-assembly check; insulation contact, air sealing and wet-location suitability are different claims.

For physical fit, use the recessed-light measurement guide to separate the trim, opening and hidden equipment. For exposure conditions, read the shower lighting guide; for a ceiling opening, cavity depth, joists and wiring, obtain the selected fixture’s current instructions and have site conditions reviewed. This page does not turn a product document into an installation approval.

Enter Verified Fixture Data, Then Review the Room

Open the calculator, choose the room use and reference plane, then enter your verified per-fixture lumens and beam angle, plus input watts if known. Auto estimates a general-lighting count from those inputs and its disclosed assumptions; it does not read a PDF, inspect your ceiling or guarantee a layout.

For this page’s 3000 K worked row, the existing Fixture model → HALO → LT56 · 3000K option loads the matched 795 lm / 8.6 W / 95.7° catalog values as read-only inputs. Confirm the source link below the selector shows LT56079FS1EWHR. For any other product or setting, choose Custom specs and use only that configuration’s verified values.

If required lumens or beam angle are absent, leave your project note as “not provided” and get the exact photometric document before relying on a product-specific result. Optional watts may be left blank. Do not borrow a neighboring SKU’s value simply to complete the form. After an estimate, compare spacing, glare, tasks and installation conditions with a qualified reviewer.

Sources and Scope

This guide is maintained by Recessed Light Calculator and uses one public manufacturer document as a worked reading exercise. It does not endorse the product, claim the document covers every option, or replace the current specification, installation instructions, local requirements or a lighting professional’s review.

Source accessed October 5, 2026: official HALO LT56 Selectable LED Trim PDF (June 16, 2026). Recheck the exact model, revision, options and test condition before purchase or installation. See model assumptions or report a source issue.