Load Cell Calibration Explained: Deadweight, Shunt and In-System Checks

By MNM Scales · Last updated November 3, 2026

Reviewed by MNM Scales technicians · Updated November 3, 2026 · Prices checked November 3, 2026

This guide is for plant engineers, maintenance teams, test labs and equipment builders who need load cells, or the scales and weighing systems built on them, calibrated with records they can show an auditor. MNM Scales has sold, calibrated and repaired scales for over 30 years from our shop in Cypress, Texas, and our TDA-registered technicians calibrate scales in the shop, by mail-in and on-site.

What load cell calibration means

A load cell turns force into a small electrical signal, rated in millivolts per volt (mV/V) of excitation at full capacity. For example, the 20,000 lb S-type cell in our Brecknell crane scale kit is rated 3.00 mV/V, with nonlinearity and hysteresis of 0.02 percent of full scale and repeatability of 0.01 percent of full scale. The indicator reads that signal and converts it to pounds or kilograms. Calibration ties the two together: known loads go on, the readings are recorded, and the indicator’s zero and span are set so the display matches the load.

• Load cell on its own: the cell is loaded in a test frame and its output is recorded against known forces. This produces the cell’s own data, such as rated output and linearity.
• Load cell in a scale or system: the cells, junction box, cable and indicator are calibrated together with test weights where they work. This is what makes a tank, hopper, platform or crane scale read correctly in use.
• Before you calibrate: a damaged or drifting cell will not hold a calibration. See how to test a load cell and our junction box guide for checks to run first.

Load cell calibration methods: deadweight, shunt and in-system

Method	How it works	What it proves	Best for
Deadweight	Known masses hang from or press on the load cell in a test frame	The cell’s output against real loads at each test point	Single cells and small capacities where weights can be applied directly
Shunt calibration	A precision resistor is switched across one arm of the bridge to simulate a known output	The indicator and wiring respond as expected; no real load is applied	Quick checks between full calibrations, using a value set by an earlier load test
Comparison to a reference cell	The cell and a reference load cell carry the same force in series	The cell’s output against the reference at each force	High capacities where enough deadweight is not practical
In-system with test weights	Certified test weights are placed on the installed scale, tank or hopper	The complete system, including mounts, junction box and indicator	Working scales and weighing systems; the check most audits ask for

For working scales, in-system calibration is the one that reflects real use. Weights should be more accurate than the scale; see our calibration weights guide and weight classes explained. Crane scales and floor scales have their own steps, covered in crane scale calibration and how to calibrate a floor scale.

Which points to check: zero, span, linearity and repeatability

1. Exercise and zero: load the system near capacity once or twice, remove the load, then record the zero reading.
2. As-found readings: before adjusting anything, record readings at the test points so the certificate shows how far the system had drifted.
3. Span: apply a load near the top of the range you use and set the indicator span so the display matches.
4. Linearity: read at several points up the range, for example 25, 50, 75 and 100 percent of capacity, then back down to check hysteresis.
5. Repeatability: repeat one test load several times and compare the readings.
6. Corner or section test: on multi-cell platforms and tanks, place the weight over each cell or section to confirm they share the load evenly.
7. Return to zero and as-left readings: confirm zero after unloading and record the final readings after adjustment.

What goes on a load cell calibration certificate

• Scale or load cell description, capacity, division and serial number
• As-found and as-left readings at each test point, with the tolerance used
• Test weights used and their certificate or traceability numbers
• Date, location, technician and conditions such as temperature
• Pass or fail result and the recommended next calibration date
• Certificate type: in-house with a certificate, or a NIST-traceable certificate; see NIST vs in-house certificates and our NIST calibration certificate service.

How often to calibrate load cells and weighing systems

• Yearly is a common starting point for scales and weighing systems in steady use.
• More often for heavy daily use, shock loading, wet or dusty areas, and any system your quality program audits.
• Right away after an overload, a dropped load, a replaced cell, junction box or indicator, or a move.
• Track as-found readings over time: if they stay within tolerance, the interval can stretch; if not, shorten it. See how often to calibrate a scale.

When a pre-calibrated load cell kit makes more sense

For a hoist, test rig or pull test that needs a reading rather than a scale, a load cell and indicator calibrated together before they ship can be simpler than building and calibrating a system on site. Our tension load cell guide covers rigging and hardware; for load cell cost by type, see load cell price.

Kit	Capacity x division	Indicator	Included	Price
MNM Scales 2,000 lb calibrated S-type kit	2,000 lb x 0.5 lb	1 in backlit display, RS-232, hold	Power supply, rechargeable battery, mounting bracket and hardware	$259
MNM Scales 5,000 lb calibrated S-type kit	5,000 lb x 0.5 lb	0.75 in backlit LCD, RS-232, peak hold; 3 AA battery power	Stainless steel mounting bracket and hardware	$314
MNM Scales 10,000 lb calibrated S-type kit	10,000 lb x 0.5 lb	0.75 in backlit LCD, RS-232, peak hold; 3 AA battery power	Stainless steel mounting bracket and hardware	$349
Brecknell 20,000 lb crane scale kit	20,000 lb x 1 lb	SBI-521 IP65 stainless, two serial ports, 80 Hz peak capture	S-type cell, two eye bolts, 20 ft cable; rechargeable battery	$799

Rules: NTEP and Texas for scales built on load cells

TDA does not require an NTEP certificate for every device, but the scale must meet NIST Handbook 44 and suit its use; some scales do need one, so we recommend NTEP models and can check yours. When load cells go into a scale used to buy, sell or charge by weight, the scale has to be legal for trade: NTEP-certified load cells and indicator, installed and calibrated to NIST Handbook 44. In Texas, a commercial scale also has to be placed in service; our TDA-registered technicians can do that. See our NTEP guide and our TDA scale certification guide, and for choosing cells, our load cell buying guide.

Calibration and rental

• Up to 2.2 kg: in-house calibration with a certificate is $95, or NIST calibration with a NIST-traceable certificate is $395.
• 2.2 to 6.2 kg: in-house with a certificate is $195, or NIST-traceable is $495.
• 6.2 to 35 kg: in-house with a certificate is $250, or NIST-traceable is $595.
• 35 to 150 kg: in-house or NIST-traceable calibration; call us for a quote.
• Over 150 kg (crane scales, kits, floor, tank and hopper systems): in-house calibration with a certificate or NIST calibration with a NIST-traceable certificate; call us for the price on your system.
• On-site service: $295 + $2 per mile per visit across the Houston area, with calibration charged per scale; see our industrial scale calibration service, scale calibration in Houston and on-site calibration.
• Mail-in, budgets, repairs and rentals: ship smaller scales for mail-in calibration, see how much scale calibration costs, have us repair the brands we sell, and rent all types of scales while yours is out of service.

Frequently asked questions

What is load cell calibration?

It compares a load cell’s or weighing system’s readings with known loads and adjusts the indicator so the display matches, then records the results on a certificate.

What is the difference between shunt calibration and deadweight calibration?

Deadweight calibration applies real, known loads. Shunt calibration switches a precision resistor across the bridge to simulate a known output, which checks the electronics but applies no load.

Can load cells be calibrated in place?

Yes. In-system calibration places certified test weights on the installed scale, tank or hopper, so the cells, junction box and indicator are checked together where they work.

How many test points does a load cell calibration need?

At least zero and a span point near capacity, plus several points up and down the range, such as 25, 50, 75 and 100 percent, to check linearity and hysteresis.

How often should load cells be calibrated?

Yearly is a common starting point. Calibrate more often under heavy use, and right away after an overload, a dropped load, or a replaced cell or indicator.

Do you calibrate load cells and weighing systems in Houston?

Yes. We calibrate scales and weighing systems in our Cypress shop, by mail-in, and on-site across the Houston area for $295 + $2 per mile per visit. Call (832) 290-3120.