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Steel Grating Load Calculator

Enter bar size, spacing and span to get the maximum uniform load (kPa/psf) and deflection — computed live from beam theory. Then send it straight to a quote.

Max uniform load (simply supported)

Capacity—
Capacity (US)—
Deflection at that load—
Span / deflection—
Get a quote for this grating →
Method: Capacity is computed from beam theory for a mild-steel bearing bar (allowable bending stress ~165 MPa, E = 200 GPa), simply supported, uniformly loaded. Indicative for selection — confirm against your governing standard (e.g. ANSI/NAAMM MBG 531) and project loading on RFQ.

Steel grating load table (19 mm spacing, kPa)

Uniform load capacity by bearing bar and clear span:

Bearing bar (mm)600 mm span900 mm span1200 mm span1500 mm span1800 mm span
25×3602715107
25×510145251611
30×514564362316
32×516573412618
40×5257114644129
50×54021791016445
65×567930217010975
75×61086482271174121

Frequently Asked Questions

How do I select the right bar grating?

Choose by the load and clear span: pick a bearing-bar size whose capacity exceeds your design load at the required span, then set the spacing for the surface and drainage you need. Our load calculator computes capacity and deflection from beam theory for any bar size and span.

How is grating load capacity calculated?

Capacity is found from beam theory: each bearing bar is treated as a simply supported beam, the allowable bending moment (section modulus × allowable stress) sets the maximum line load, which is divided by the bar spacing to give the area load, with deflection checked separately.

What deflection is acceptable for grating?

A common serviceability limit is span/200 for pedestrian grating; always confirm against your governing standard and loading on the quote request.

What this calculator does and why grating load capacity matters

Steel grating has one job in a platform or walkway: carry its load — whether that is a uniform load spread across the panel (people, snow, stored material) or a concentrated load from a wheel or a single foot — while deflecting no more than the span can tolerate. This calculator treats each bearing bar as a simply supported beam and returns the maximum uniform load (in kPa and psf) plus the resulting deflection, so you can match a bar size to your design load before you commit to a spec.

Load capacity is driven by three things you control: bearing bar size (a deeper bar adds capacity fast, because section modulus rises with the square of bar height), bar spacing (closer bars share the load over more steel per square metre), and clear span (capacity falls roughly with the square of the span). Under-spec the grating and it sags, bounces or — in the worst case — fails under a wheel or crowd load; over-spec it and you pay for steel and shipping weight you did not need. Getting this right is the difference between a platform that feels solid underfoot and one that is either unsafe or unnecessarily expensive. Use the calculator to narrow the field, then send the result straight to our team for a quote against your certified load tables.

Worked examples

Example A — 1 m walkway carrying pedestrian load

A maintenance walkway has a 1,000 mm clear span and a design uniform pedestrian load of about 5 kPa (a common live-load target for access walkways). A 30×5 mm bearing bar at 30 mm spacing comfortably exceeds this at a 1 m span — indicatively in the order of ~140 kPa of allowable uniform capacity, with deflection well inside a span/200 serviceability limit. Plenty of margin, so the choice can instead be driven by surface (serrated for grip) and drainage rather than strength. Indicative, per standard load tables — confirm with your engineer/manufacturer.

Example B — platform with a concentrated wheel load

An access platform must take an occasional trolley wheel of about 3 kN over a small contact patch at mid-span, rather than a spread-out crowd. A concentrated load is far more demanding than the same total weight spread uniformly — it loads only the few bars directly under the wheel, so the governing bar sees a much higher moment. The fix is a deeper, more closely spaced bar (for example a 40×5 mm or 50×5 mm bar at tight spacing) and a check that the wheel does not bridge a gap. Uniform-load figures alone will over-state what the panel can take under a point load, so a concentrated case must be checked separately. Indicative — a wheel/point load case must be confirmed against the manufacturer's certified concentrated-load tables and a qualified engineer.

Example C — doubling the span sharply cuts allowable load

Keep the bar and spacing fixed and change only the span. Because allowable uniform load scales with 1/span², going from a 900 mm to an 1,800 mm span (a 2× increase) cuts allowable capacity to roughly a quarter, not a half. For a 30×5 mm bar that is indicatively in the order of ~64 kPa at 900 mm dropping to ~16 kPa at 1,800 mm. Deflection grows even faster (with span to the fourth power), so a long unsupported span is usually governed by deflection, not stress. The practical lesson: adding an intermediate support to halve the span buys back far more capacity than going up one bar size. Indicative, per standard load tables — confirm span and support conditions with your engineer/manufacturer.

Indicative steel grating load capacity by bearing bar & span

The table below gives indicative maximum uniform load (kPa) for common mild-steel bearing bars treated as simply supported beams at a representative bar spacing. Figures follow published load-table principles (allowable bending stress ~165 MPa, simply supported, uniform load) and are for early selection only. They are not a substitute for a manufacturer's certified load table or a structural engineer's sign-off — always confirm before specifying, especially for safety-critical or concentrated-load applications.
Bearing bar (mm)600 mm span1000 mm span1500 mm span2000 mm spanTypical use
25×3~60~22~10~5Light pedestrian / covers
25×5~100~36~16~9Walkways, light access
30×5~145~52~23~13General platforms / walkways
40×5~255~92~41~23Industrial platforms
50×5~400~145~64~36Heavier platforms / trafficked
65×5~680~245~109~61Heavy-duty load areas
75×6~1085~390~174~98Vehicle / heavy plant zones

Indicative only, per published load-table principles — not certified values. Capacity falls with roughly 1/span², so small span changes move these numbers a lot. Concentrated (wheel/point) loads, dynamic loads and special steels are NOT covered here and must be checked separately. Confirm every selection against GoGrating's certified load tables and a qualified structural engineer before ordering. See our load tables or request a quote for project-specific verification.

Who uses this and where

Grating load selection touches almost every heavy-industry sector. Industrial platforms and walkways need the right balance of capacity, weight and open area; oil & gas facilities specify grating for offshore decks, refinery access and explosion-prone areas where slip resistance and corrosion rating matter as much as load; water treatment plants want capacity plus drainage and galvanised durability over tanks and channels; power stations use grating for boiler platforms and cable-tray walkways; mining demands heavy-duty bars that survive impact and abrasion; and infrastructure and drainage projects need trench covers and bridge walkways rated for foot or occasional vehicle loads. The engineers and buyers running these specs — structural and civil engineers, EPC contractors, procurement teams, and installation contractors — use a calculator like this to shortlist a bar size fast, then confirm against certified data. Explore matching products in our steel grating range or industrial platform applications.

Industrial platformsWalkwaysOil & gasWater treatmentPower generationMiningInfrastructure & drainageStructural engineersEPC contractorsProcurement & contractors

How we calculate it — and its limits

This calculator is built on standard grating engineering and published load-table principles, not on proprietary test data. It models each bearing bar as a simply supported beam in mild steel, derives the allowable bending moment from the bar's section modulus and an allowable bending stress, and converts the resulting line load to an area load using your bar spacing; deflection is then checked from beam theory. The results are indicative for early selection and become less reliable the further your real conditions drift from these assumptions. They must be confirmed against the manufacturer's certified load tables and a qualified structural engineer before use in any safety-critical application. We present this neutrally so you can make an informed decision — there is no fabricated test certificate behind these numbers.

  • Bars are modelled as simply supported (pinned ends, single span) — fixed ends, continuous spans or banding bars change the result.
  • Loads are assumed uniform; concentrated wheel/point loads, dynamic or impact loads are not covered and are typically more severe.
  • Allowable bending stress (~165 MPa) and E (200 GPa) assume mild steel; stainless, aluminium or special alloys behave differently.
  • A serviceability deflection limit of about L/200 is typical for pedestrian grating, but your governing standard (e.g. ANSI/NAAMM MBG 531) may require a different limit.
  • Cross-bar effect, corrosion allowance, fixings and connection capacity are not modelled — final selection must be verified by a qualified engineer against certified data.

Key terms

Bearing bar
The main load-carrying bars of a grating panel, running in the direction of the span. Their depth (height) and thickness set most of the panel's strength and stiffness — a taller bar adds capacity faster than a thicker one.
Span
The clear distance between the supports that the grating bridges. Allowable load drops with roughly the square of the span, and deflection grows even faster, so span is usually the single biggest driver of capacity.
Uniform vs concentrated load
A uniform load is spread evenly across the panel (people, snow, stored material), measured in kPa or psf. A concentrated load acts on a small area (a wheel, a leg, a single foot) and is far more demanding because it loads only the bars directly beneath it — it must be checked separately.
Allowable deflection
The maximum sag the grating may have under load before it is considered too flexible to use, usually expressed as a fraction of span (e.g. span/200). It is a serviceability limit for comfort and function, often governing long spans before strength does.

More frequently asked questions

Does closer bearing-bar spacing increase load capacity?

Yes. For a given bar size and span, closer spacing puts more bearing bars under each square metre, so the uniform load each bar carries drops and the panel's area capacity (kPa/psf) rises. The trade-off is more steel, more weight and less open area for drainage. Use the calculator to see how spacing changes capacity, then balance it against surface and drainage needs.

Why is a wheel load harder on grating than the same weight spread out?

A spread-out (uniform) load shares across all the bars in the panel, while a wheel or point load concentrates on the few bars directly beneath it — and can even bridge across the gap between bars. So the governing bar sees a much higher bending moment than a uniform figure suggests. Always check concentrated loads against the manufacturer's certified concentrated-load tables and a qualified engineer; this tool's uniform-load output should not be used for wheel loads on its own.

Can I use these numbers to specify grating for a real project?

Use them to shortlist a bar size quickly, not to finalise a spec. The figures here are indicative, based on simply supported uniform-load beam theory and published load-table principles. Before you order, confirm the selection against GoGrating's certified load tables and have a qualified structural engineer sign off on your actual loads, span, support conditions and governing standard — especially for safety-critical platforms or vehicle access. Send your span and load on the request-quote form and our team will verify it for you.